Glycosylation in premature ovarian insufficiency: from genetic etiology to precision diagnostics.

Glycosylation biomarkers hold significant potential for advancing the diagnosis and management of ovarian insufficiency. A critical step in their translation is comparing their prospective value against current clinical standards, such as anti-Müllerian hormone, FSH, and antral follicle count. While anti-Müllerian hormone and antral follicle count are valuable for assessing ovarian reserve, they are often more indicative of the consequence of follicular depletion rather than the underlying etiology. Glycosylation signatures, by contrast, could provide earlier insights into pathogenic processes, offer potential for etiological subtyping of POI, and serve as sensitive indicators of subtle dysfunction before a significant decline in reserve occurs. Evidence from congenital disorders of glycosylation, particularly those associated with PMM2 variants, suggests that aberrant glycosylation patterns may serve as biomarkers correlated with POI pathogenesis [ 59 ]. A landmark study using solid-phase antibody arrays identified distinct serum proteomic profiles in POI patients compared to menopausal and fertile controls. The expressions of Neurturin, Frizzled-5, Serpin D1, MMP-7, ICAM-3, IL-17 F, IFN-γR1, IL-29, IL-17R, IL-17 C, and Soggy 1 were significantly down-regulated, while Afamin was significantly upregulated. These findings suggest these proteins may be involved in POI pathogenesis and could serve as novel serum biomarkers [ 99 ]. To envision the practical integration of glycomics into POI diagnosis, specific application scenarios can be proposed. For instance, serum N-glycan profiling could be developed into a diagnostic panel to stratify idiopathic POI into potential etiological subtypes. Based on known associations between glycan structures and disease mechanisms, distinct glycan signatures are hypothesized to correlate with different underlying pathologies. A profile characterized by features such as increased bisecting GlcNAc and reduced sialylation might suggest an autoimmune component, reflecting broader inflammatory processes often seen in autoimmunity. Conversely, a signature featuring truncated or underprocessed high-mannose or hybrid-type glycans could point toward underlying genetic defects in the N-glycosylation pathway, similar to those observed in congenital disorders of glycosylation. Such etiological stratification, if validated, would directly inform personalized clinical management. It could guide decisions such as initiating early immunosuppressive therapy for patients with an autoimmune signature or providing targeted genetic counseling and testing for those with a profile suggestive of a genetic etiology. Preliminary clinical studies have indeed reported differences in serum glycan profiles between POI patients and healthy controls, supporting the translational potential of this approach. While the initial development and implementation of such a specialized diagnostic panel would involve higher costs, this investment could be offset by its potential to enable more targeted interventions, avoid ineffective treatments, and personalize fertility preservation strategies, ultimately improving long-term clinical outcomes and cost-effectiveness. Furthermore, mass spectrometry-based glycomics, a technique pioneered in ovarian cancer research, has revolutionized biomarker discovery. These high-resolution techniques enable comprehensive characterization of protein glycosylation patterns, facilitating the identification of POI-specific glycan signatures [ 100 ]. Such advancements could bridge the gap between glycosylation profiling and clinical diagnostics, allowing for earlier and more precise POI detection. However, a critical challenge remains in translating these discoveries into clinically applicable tools. The proposed biomarkers require rigorous validation in large, independent, and multi-center cohorts to establish their diagnostic sensitivity, specificity, and predictive value. Furthermore, the high cost and technical complexity of advanced glycomics currently limit their use to research settings, necessitating the development of simplified, standardized, and cost-effective assays for routine clinical adoption. Current POI management primarily relies on HRT for symptom palliation but does not address the underlying pathological mechanisms or restore ovarian endocrine and paracrine functions [ 101 ]. Recent therapeutic innovations targeting molecular pathogenesis show transformative potential. These include receptor-specific biologics, exosome-based regeneration therapies, and glycosylation pathway modulation. For example, the TrkB-targeted agonistic antibody Ab4B19 exemplifies this shift, demonstrating superior efficacy over conventional therapies by reactivating ovarian TrkB signaling and improving oocyte quality in both age-related and chemotherapy-induced POI models [ 102 ]. Complementary studies on FUT8/FSHR interactions further validate glycosylation’s role in modulating gonadotropin receptor sensitivity, suggesting synergistic therapeutic strategies [ 103 ]. Regenerative approaches utilizing exosomes derived from menstrual blood- derived stem cells (MenSC-EXOs) highlight the therapeutic potential of extracellular vesicle. Through TSP-1-mediated activation of TGF-β/SMAD3 and PI3K/AKT pathways, MenSC-EXOs effectively reduce granulosa cell apoptosis and enhance follicular survival [ 104 ]. This mechanism aligns with FUT8-mediated intercellular communication, collectively supporting exosome-based interventions as biologically rational strategies. Emerging genetic insights into FUT8 and MGAT family mutations underscore glycosylation defects as central to POI etiology [ 19 , 103 ]. Promising precision approaches under investigation include CRISPR-Cas9 gene correction, enzyme replacement therapies (e.g., L-fucose supplementation for FUT8 deficiency), and small-molecule glycosylation modulators. Notwithstanding this promising preclinical landscape, most of these strategies remain in early developmental stages. The path to clinical application is long, requiring rigorous safety and efficacy trials. Accelerating this translational research is imperative. These application-specific challenges, which include the specificity of therapeutic targets, the need for patient stratification, and the inherent complexity of developing biologics and gene-based therapies, are rooted in the broader, fundamental challenges inherent to glycosylation research and its clinical translation. These overarching challenges will be discussed in the next section.

Translating glycosylation research to clinical practice for POI faces several challenges. First, glycosylation is a highly complex process involving a vast number of enzymes and pathways. Understanding the precise role of each component in POI is difficult, and this complexity complicates the development of targeted therapies. Second, the absence of standardized protocols for glycosylation-based diagnostics or therapies compromises both research reproducibility and clinical benchmarking. Third, significant interspecies differences in glycosylation machinery between conventional animal models and humans limits the predictive validity of preclinical studies, necessitating the development of humanized model systems. Technological innovations are addressing these challenges. Therapeutically, glycoengineering of mammalian, insect, and yeast expression systems now enables the production of recombinant proteins with humanized glycosylation patterns, potentially restoring physiological glycan-protein interactions in POI [ 105 ]. Analytically, next-generation platforms are transforming research: automated mass spectrometry achieves single-isomer resolution for quantitative glycan profiling [ 106 ], while high-density glycan microarrays facilitate system-wide mapping of protein-glycan interactions [ 107 ].These advances enable a transition from descriptive glycomics to mechanistic and therapeutic exploration. To advance this field strategically, future efforts should be focused on three interconnected domains. First, mechanistic investigations must delineate ovary-specific glycosylation networks through the integrated application of single-cell RNA sequencing, structural glycobiology, and functional genomics, which will clarify the critical crosstalk between glycosyltransferases and folliculogenesis. Second, to bridge the gap between discovery and application, the clinical translation of findings requires the establishment of international consensus guidelines for biomarker validation and therapeutic development. This can be achieved by forming multidisciplinary consortia that unite glycobiologists, reproductive endocrinologists, and regulatory experts. Finally, it is imperative to strengthen the global research infrastructure by developing open-access glycomics databases, standardized biospecimen repositories, and patient-engaged research frameworks. These initiatives will ensure the clinical relevance of research and significantly accelerate the translation of knowledge into tangible benefits for patients.

In conclusion, while glycosylation dysregulation represents a promising frontier in POI research, its clinical translation requires careful evaluation. It is important to acknowledge the current limitations, including that much of the evidence derives from single-gene mutation case studies or small cohorts, lacking validation in large, multicenter population. Furthermore, the causal relationship between specific glycan changes and POI pathogenesis often remains correlative, necessitating deeper functional validation. Current advances in biomarkers and targeted therapies remain predominantly in preclinical stages, facing challenges in validation, standardization, and safety assessment. Future research must therefore prioritize large-scale collaborative studies to validate candidate glycosylation biomarkers. Mechanistically, emerging technologies like single-cell glycomics should be leveraged to decipher ovary cell-specific glycosylation networks, which will be crucial for understanding folliculogenesis and identifying precise therapeutic targets. A more critical, evidence-based approach will be essential to translate these mechanistic insights into meaningful clinical applications for POI patients.

Premature ovarian insufficiency (POI) is clinically defined as the loss of ovarian function before the age of 40 and characterized by amenorrhea (lasting ≥ 4 months), elevated serum follicle-stimulating hormone (FSH > 25 IU/L), and hypoestrogenism [ 1 , 2 ]. This condition has significant reproductive, psychosocial, and long-term health consequences, including infertility, osteoporosis, and increased risk of cardiovascular disease, and diminished quality of life [ 3 , 4 ]. Historically, various terms have been used to describe this disorder, such as ‘primary ovarian insufficiency’ [ 5 ], ‘premature menopause’ [ 6 ], and ‘premature ovarian failure’ [ 7 ]. Although the most recent guideline from the European Society of Human Reproduction and Embryology (ESHRE) recommends ‘premature ovarian failure’ as the standard nomenclature, the term ‘primary ovarian insufficiency’ is still frequently used [ 8 ]. Epidemiological studies indicate that POI has a prevalence of approximately 1% in women under 40 in Western populations, with the incidence decreasing sharply in younger age groups (e.g., 0.1% in women under 30 years) [ 9 , 10 ]. The etiology of POI is multifactorial, involving genetic predispositions [ 11 , 12 ], autoimmune disorders [ 13 ], environmental factors [ 14 ], and metabolic abnormalities [ 15 , 16 ]. Emerging evidence implicates dysregulation of post-translational modifications, particularly glycosylation, as a key pathogenic driver in idiopathic POI [ 17 ]. Glycosylation, the enzymatic process of attaching carbohydrate moieties to proteins or lipids, is indispensable for protein folding, hormone-receptor interactions, and tissue-specific signaling [ 18 ]. It plays a crucial role in normal ovarian physiology through multiple mechanisms. For instance, in ovarian cancer, MGAT3 - mediated glycosylation of tetraspanin CD82 at asparagine 157 is essential for its inhibitory effect on cancer cell migration and metastasis, both in vitro and in vivo [ 19 ]. Mechanistically, this glycosylation disrupts integrin α5β1-mediated cellular adhesion to fibronectin, thereby inhibiting the integrin signaling pathway required for cellular migration. In normal ovarian function, the glycosylation status of FSH also has distinct effects. FSH is secreted as two glycosylation variants: partially glycosylated FSH (FSH21/18) and fully glycosylated FSH (FSH24). Studies on mouse pre-antral follicles indicate that FSH21/18, as well as an 80:20 ratio of FSH21/18 to FSH24, promote follicle growth. In contrast, FSH24 and a 20:80 ratio reduce follicle survival rates, accompanied by altered expression of key genes regulating follicular function [ 20 ]. This review critically explores the relationship between glycosylation and POI by systematically examining the functions of key glycosylation pathway genes, their roles in ovarian physiology, and their implications in POI pathophysiology. By synthesizing existing literature, this review aims to provide insights into how glycosylation abnormalities may serve as potential biomarkers or therapeutic targets for managing POI.

Glycosylation is a post-translational modification mediated by glycosyltransferases. It involves the covalent attachment of glycan chains to specific amino acid residues, primarily asparagine (Asn), serine(Ser), or threonine(Thr), via glycosidic bonds [ 21 ]. This highly coordinated process occurs predominantly in the endoplasmic reticulum (ER), Golgi apparatus, and lysosomes. It requiring the interplay of hundreds of enzymes, including glycosyltransferases and glycosidases, as well as inter-organelle collaboration [ 22 ]. During synthesis, glycosyltransferases, a type II transmembrane glycoprotein with catalytic domains oriented toward the lumen of the ER and Golgi, utilize nucleotide sugars such as UDP-GlcNAc, GDP-Man, and CMP-NeuAc as donor substrates. They sequentially transfer monosaccharides or oligosaccharides to protein backbones, generating structurally diverse glycan modifications [ 23 ]. Based on the linkage between the glycan and the amino acids, glycosylation is classified into four main types: O-glycosylation, N-glycosylation, C-glycosylation, and glycosylphosphatidylinositol (GPI)-anchor attachment. Among these, N- and O-glycosylation are the most common and involve most of the glycosylation machinery associated with disease pathogenesis and progression [ 22 ]. Newly synthesized glycoproteins undergo initial folding and core glycosylation in the ER. This is followed by glycan trimming mediated by enzymes like mannosidases, and terminal modifications such as sialylation, which is catalyzed by sialyltransferases in the Golgi apparatus [ 24 , 25 ]. The mature glycoproteins are then sorted via the vesicular transport system. Some are transported back to the ER by coat protein complex I (COPI), while others are delivered to the plasma membrane, where they facilitate essential biological functions. These functions include cell adhesion mediated by integrin-matrix interactions, signal transduction via growth factor receptor activation, and immune defense facilitated by mucin-based barrier formation [ 26 ]. Glycans regulate protein function through multiple mechanisms. The steric hindrance imposed by glycans can shield proteolytic cleavage sites; for example, IgG Fc glycosylation extends antibody half-life approximately threefold [ 27 ]. Specific glycan structures act as molecular “barcodes” that mediate cellular communication, such as the selectin-sialylated glycan interactions that drive inflammatory cell migration [ 28 ]. Furthermore, ER lectin chaperones like calnexin participate in protein quality control by recognizing glycan structures and directing misfolded proteins toward refolding or ER-associated degradation (ERAD) pathways [ 29 ]. The precise regulation of glycosylation networks is critical for maintaining cellular homeostasis, and its dysregulation contributes to a spectrum of conditions, including congenital disorders of glycosylation, aging-related diseases, cardiovascular disease, and reproductive dysfunction [ 30 – 35 ]. N-glycosylation is a highly regulated and evolutionarily conserved post-translational modification. Its biosynthesis begins in the lumen of the ER with the assembly of a lipid-linked oligosaccharide precursor, Glc 3 Man 9 GlcNAc 2 -pyrophosphoryl-dolichol (Glc 3 Man 9 GlcNAc 2 -PP-Dol) [ 36 ]. This process involves sequential enzymatic reactions catalyzed by the asparagine-linked glycosylation (ALG) family of glycosyltransferases. These enzymes utilize sugar nucleotides (e.g., UDP-GlcNAc, GDP-Man) synthesized in the cytosol to build the oligosaccharide on the ER membrane-embedded dolichol phosphate (Dol-P) carrier [ 37 ]. The completed lipid-linked oligosaccharide is then transferred en bloc by the oligosaccharyltransferase (OST) complex to the amide nitrogen of an Asn residue within the canonical sequon (-Asn-X-Ser/Thr-, where X ≠ Pro) of a nascent polypeptide. This transfer occurs co-translationally, before protein disulfide bond formation and tertiary folding, ensuring the sequon is accessible to the OST complex [ 38 ]. Newly synthesized glycoproteins undergo ER quality control, where α-glucosidases I and II sequentially remove the three terminal glucose residues and one mannose residue, generating Man 8 GlcNAc 2 intermediates [ 39 ]. The calnexin/calreticulin cycle monitors these modifications, retaining misfolded proteins for refolding or targeting them for ERAD [ 40 ]. Properly folded glycoproteins bearing the Man₈GlcNAc₂ structure are trafficked to the Golgi apparatus. There, compartment-specific enzymes process the glycans into three main types: high-mannose, complex, and hybrid N-glycans [ 41 ]. The terminal structures of complex N-glycans, which may include N-acetylglucosamine, N-acetylgalactosamine, sialic acid, and fucose, determine the glycan’s properties. There structures influence protein conformation, antigenicity, biological activity, and molecular recognition, thereby playing critical roles in diverse biological processes [ 42 , 43 ] Fig. 1 . Fig. 1 Biosynthesis of N-glycosylation Biosynthesis of N-glycosylation O-glycosylation in eukaryotes primarily encompasses two major forms: O-linked β-N-acetylglucosamine (O-GlcNAcylation) and mucin-type O-acetylgalactosamine (O-GalNAcylation) [ 44 ]. O-GlcNAcylation occurs in various intracellular compartments, including the nucleus, cytoplasm, mitochondria, the cytoskeleton, and the ER [ 45 ]. This modification is dynamically regulated by two enzymes: O-GlcNAc transferase (OGT), which adds the O-GlcNAc moiety to Ser or Thr residues of nucleocytoplasmic proteins, and O-GlcNAcase (OGA), which remove it [ 46 ]. The donor substrate, uridine diphosphate N-acetylglucosamine (UDP-GlcNAc), is synthesized via the hexosamine biosynthetic pathway, making O-GlcNAcylation a sensitive nutrient sensor [ 47 ]. It acts as a master regulator of various cellular processes, including transcriptional regulation, cellular metabolism, protein enzymatic activity, and subcellular localization [ 48 ]. O-GalNAcylation is characterized by clustered modifications on Ser- and Thr-rich regions of proteins, such as mucins. It is prevalent on most membrane-bound and secreted proteins [ 49 ].Cell-surface mucins mediate cell-environment communication, while secreted mucins form protective mucus essential for pathogen defense and immune regulation. This type of glycosylation takes place in the Golgi apparatus, where a family of over 20 polypeptide N-acetylgalactosaminyltransferases (GALNTs) initiates the process [ 50 ]. A GALNT enzyme transfers an GalNAc from UDP-GalNAc to a Ser/Thr residue, forming the Tn antigen (GalNAcα1-O-Ser/Thr) [ 51 ]. This core structure is often extended; for example core 1 β1,3-galactosyltransferase (C1GalT1) adds a galactose to form the core 1 structure (T antigen, Galβ1-3GalNAcα1-O-Ser/Thr) [ 52 ]. Various glycosyltransferases can further modify the Tn and T antigens, generating diverse O-glycan structures by adding sugars like galactose, fucose, and sialic acid, forming linear or branched chains via specific glycosidic linkages [ 53 ]. Finally, sialyltransferases such as ST3GAL and ST6GAL can cap these structures by adding sialic acid residues. These modifications occur progressively as proteins move through the cis- and trans-Golgi compartments before final secretion, as seen with proteins like MUC5AC [ 54 ] Fig. 2 . Fig. 2 Biosynthesis of O-glycosylation A  Biosynthesis of O-GlcNAcylation B  Biosynthesis of mucin-type O-GalNAcylation Biosynthesis of O-glycosylation A  Biosynthesis of O-GlcNAcylation B  Biosynthesis of mucin-type O-GalNAcylation Abnormal glycosylation has been implicated in numerous reproductive disorders, including POI, endometriosis, polycystic ovary syndrome (PCOS), recurrent implantation failure, pregnancy loss, pregnancy complications, and male factor infertility [ 35 , 55 – 57 ]. Recent studies have identified specific glycosylation-related genes that, when mutated, may contribute to the onset of POI [ 58 ]. Notably, Phosphomannomutase 2 (PMM2), a key enzyme in the N-glycosylation pathway, is essential for converting mannose-6-phosphate to mannose-1-phosphate, a critical step in glycoprotein synthesis. Mutations in PMM2 cause congenital disorders of glycosylation (CDG-Ia), leading to defective N-glycan synthesis and subsequent disruptions in ovarian follicle function and maturation. This impairment can result in reduced ovarian reserve and functionality [ 59 , 60 ]. Similarly, the ALG gene family, including ALG6 and ALG8, is critical for synthesizing glycosylation precursors [ 61 , 62 ]. These genes ensure proper protein folding and glycan assembly in the early steps of the N-glycosylation. Mutations in ALG gene can cause congenital disorders with systemic symptoms, including reproductive anomalies such as POI, where oocyte quality and follicular development may be compromised due to impaired glycoprotein synthesis. Additionally, POF1B has been directly linked to POI. While primarily recognized for its role in cell adhesion and signaling, emerging evidence suggests potential interactions with glycosylation pathways, indicating that POF1B mutations may contribute to altered glycosylation patterns in ovarian tissues, further impacting ovarian health [ 63 , 64 ]. Other genes, such as CST3 (Cystatin C) and members of the GALNT family, are involved in O-glycosylation, which is critical for regulating glycoproteins in the ovarian microenvironment [ 65 ]. Abnormalities in the expression or function of these genes may disrupt the glycosylation of ovarian hormones and signaling molecules, thereby affecting follicle development and hormone regulation. Collectively, mutations in these glycosylation-related genes highlight a potential mechanistic pathway wherein dysregulated glycosylation contributes to POI development (Table 1 ). Table 1 Summary of Glycosylation-Related genes implicated in premature ovarian insufficiency Gene Pathway/Primary Function Proposed Mechanism in POI Reference PMM2 λ Pathway: N-glycosylation λ Function: Catalyzesthe conversion of mannose-6-phosphate to mannose-1-phosphate, a critical early step. λ Mutations cause a congenital disorder of glycosylation (CDG-Ia) λ Leads to defective N-glycan synthesis and impaired glycoprotein folding. λ Disrupts oocyte development and follicle maturation, resulting in diminished ovarian reserve. [ 59 , 69 , 70 ] ALG family (ALG6, ALG8) λ Pathway: N-glycosylation λ Function: Encode enzymes for the synthesis of lipid-linked oligosaccharide (LLO) precursors in the endoplasmic reticulum. λ Mutations disrupt the early steps of N-glycan precursor assembly λ Compromises glycoprotein function critical for oocyte quality and folliculogenesis λ Associated with CDG phenotypes that include POI. [ 62 , 72 , 74 , 75 ] SRD5A3 λ Pathway: N-glycosylation λ Function: Catalyzes the reduction of polyprenol to dolichol, a key step in dolichol-phosphate (Dol-P) synthesis. λ Deficiency impairs the synthesis of Dol-P, an essential lipid carrier for N-glycosylation λ Disrupts the entire protein N-glycosylation pathway. λ Adversely affects follicle maturation, leading to ovarian insufficiency. [ 79 , 80 , 83 ] POF1B λ Primary Role: Actin cytoskeleton organization and cell adhesion. λ Potential Link: May interact with glycosylation pathways. λ Mutations destabilize ovarian follicular cell structures and follicle integrity. λ Directly linked to familial forms of POI. λ Potential disruption of glycosylation may exacerbate ovarian dysfunction. [ 64 , 87 , 89 ] GALNT family λ Pathway: O-glycosylation λ Function: Initiate O-glycosylation by transferring GalNAc to serine/threonine residues of proteins. λ Mutations impair O-glycosylation of key ovarian proteins (e.g., hormones, receptors). λ Affects protein stability, cell signaling, and communication, which are crucial for follicle development. λ Altered O-glycosylation is implicated in POI pathogenesis. [ 95 – 97 ] Summary of Glycosylation-Related genes implicated in premature ovarian insufficiency λ Pathway: N-glycosylation λ Function: Catalyzesthe conversion of mannose-6-phosphate to mannose-1-phosphate, a critical early step. λ Mutations cause a congenital disorder of glycosylation (CDG-Ia) λ Leads to defective N-glycan synthesis and impaired glycoprotein folding. λ Disrupts oocyte development and follicle maturation, resulting in diminished ovarian reserve. λ Pathway: N-glycosylation λ Function: Encode enzymes for the synthesis of lipid-linked oligosaccharide (LLO) precursors in the endoplasmic reticulum. λ Mutations disrupt the early steps of N-glycan precursor assembly λ Compromises glycoprotein function critical for oocyte quality and folliculogenesis λ Associated with CDG phenotypes that include POI. λ Pathway: N-glycosylation λ Function: Catalyzes the reduction of polyprenol to dolichol, a key step in dolichol-phosphate (Dol-P) synthesis. λ Deficiency impairs the synthesis of Dol-P, an essential lipid carrier for N-glycosylation λ Disrupts the entire protein N-glycosylation pathway. λ Adversely affects follicle maturation, leading to ovarian insufficiency. λ Primary Role: Actin cytoskeleton organization and cell adhesion. λ Potential Link: May interact with glycosylation pathways. λ Mutations destabilize ovarian follicular cell structures and follicle integrity. λ Directly linked to familial forms of POI. λ Potential disruption of glycosylation may exacerbate ovarian dysfunction. λ Pathway: O-glycosylation λ Function: Initiate O-glycosylation by transferring GalNAc to serine/threonine residues of proteins. λ Mutations impair O-glycosylation of key ovarian proteins (e.g., hormones, receptors). λ Affects protein stability, cell signaling, and communication, which are crucial for follicle development. λ Altered O-glycosylation is implicated in POI pathogenesis. PMM2 is a critical enzyme associated with congenital disorders of glycosylation (CDG-Ia) [ 66 ]. It catalyzes the conversion of mannose-6-phosphate to mannose-1-phosphate, a pivotal step in generating the nucleotide sugars required for N-glycan synthesis [ 67 ]. Mutations in the PMM2 gene lead to impaired N-glycan formation, resulting in defective glycosylation of numerous proteins, which affects their folding, stability, and function [ 68 ]. Research has established a strong link between PMM2 mutations and ovarian dysfunction. Deficient PMM2 activity hinders oocyte development and survival. Patients frequently present with POI symptoms, including reduced ovarian reserve and abnormal hormone levels [ 59 ]. Animal models with targeted PMM2 mutations exhibit compromised follicle development and reduced fertility, underscoring its role in ovarian health [ 69 , 70 ]. These models show that PMM2 dysfunction disrupts both the ovarian reserve and the hormonal milieu necessary for reproduction. The potential for therapeutic interventions targeting PMM2 mutations is an area of growing interest. Strategies such as gene editing technologies, including CRISPR-Cas9, offer promising avenues for restoring PMM2 function or compensating for its deficiency. Such approaches could potentially ameliorate the reproductive challenges faced by individuals with PMM2-related POI, paving the way for innovative treatments that address the underlying genetic causes of ovarian dysfunction [ 66 ]. Continued investigation into the role of PMM2 in glycosylation and ovarian biology is vital for developing effective POI management strategies. The ALG gene family (e.g., ALG6, ALG8) plays an integral role in the synthesis of N-glycosylation precursors [ 71 ]. These genes encode enzymes critical for glycoprotein biosynthesis, particularly in forming the N-glycan structures essential for proper protein folding and function [ 62 , 72 ]. Mutations in the ALG gene family can severely disrupt N-glycosylation, leading to multi-system dysfunctions. The impact on ovarian function is significant, as aberrant glycosylation can affect oocyte quality, follicular development, and overall reproductive health by impairing the function of hormones and signaling molecules crucial for regulating ovarian function [ 73 ]. Certain ALG gene mutations are linked to congenital disorders of glycosylation, where patients often present with reproductive system abnormalities, including POI [ 74 ]. For example, ALG6 mutations have been associated with ovarian insufficiency, like due to impaired glycoprotein synthesis during follicular development, highlighting the essential role of ALG6 in ovarian function [ 75 ]. The clinical manifestations of ALG gene mutations include a spectrum of POI symptoms, such as reduced ovarian reserve, hormonal imbalances, and associated reproductive challenges [ 76 ]. Potential therapeutic interventions are being explored, including glycosylation remedial therapies aimed at correcting the enzymatic deficiencies, hormone replacement therapy (HRT) to manage symptoms and support reproductive health [ 77 , 78 ]. Ongoing research is essential to deepen our understanding of the ALG gene family’s role in glycosylation and its implications for ovarian function, which will inform the development of targeted therapies for affected individuals. The SRD5A3 gene plays a pivotal role in glycosylation by contributing to the synthesis of Dol-P, an essential lipid carrier in the N-glycosylation pathway [ 79 , 80 ]. Dol-P facilitates the transfer of oligosaccharides to nascent polypeptides, which is crucial for proper glycoprotein folding and maturation [ 81 ]. Mutations in SRD5A3 can lead to N-glycosylation abnormalities, affecting various organ systems, including the ovaries [ 82 ]. Disruption of normal glycosylation processes is thought to impair ovarian tissue development and function, leading to reproductive challenges. Patients with SRD5A3 mutations may present with POI symptoms, such as irregular menstruation, infertility, and diminished ovarian reserve [ 83 ]. Research suggests that SRD5A3 deficiency can adversely impact follicle maturation, which is vital for normal ovarian function and fertility, potentially contributing to premature ovarian failure [ 84 ]. While the direct mechanisms linking SRD5A3 to POI are still under investigation, existing evidence indicates a close relationship between this gene and follicular development [ 85 ]. Future research should focus on elucidating the specific molecular mechanisms by which SRD5A3 mutations lead to abnormal ovarian function. Understanding these pathways may reveal potential therapeutic targets for managing POI in patients with SRD5A3-related glycosylation disorders [ 86 ]. The POF1B gene is a well-established genetic factor associated with POI [ 87 ]. Mutations in this gene have been linked to early-onset ovarian insufficiency. POF1B encodes a protein involved in cell adhesion processes, which are essential for maintaining the structural integrity of ovarian follicles [ 64 ]. Emerging evidence also suggests potential links between POF1B and glycosylation pathways, indicating a multifaceted role in cellular function [ 88 ]. Mutations can disrupt ovarian cell structures, particularly cell-cell adhesion [ 89 ], impairing follicle survival and development, leading to decreased ovarian reserve and infertility [ 90 ]. Loss of POF1B may hinder functional cellular networks supporting oocyte maturation and hormone regulation, resulting in POI symptoms [ 63 ]. Understanding the interplay between POF1B and glycosylation pathways is an emerging area of research [ 91 ]. As glycosylation is vital for protein function and cellular interactions, disruptions in this process may exacerbate the effects of POF1B mutations on ovarian health [ 92 ]. Future studies should focus on elucidating the precise mechanisms by which POF1B interacts with glycosylation processes and how these interactions influence ovarian function. Clinically, individuals with POF1B-related POI present with symptoms such as amenorrhea, diminished fertility, and low estrogen levels [ 93 ]. Management typically involves HRT to alleviate symptoms and restore hormonal balance. For those seeking conception, assisted reproductive technologies (ART) may be considered, underscoring the need for a personalized approach to managing POI in patients with POF1B mutations [ 94 ]. The integral role of POF1B in maintaining ovarian function, through both cell adhesion and potential glycosylation-related mechanisms, highlights the complexity of POI pathogenesis. Ongoing research into POF1B will be crucial for developing targeted therapeutic strategies [ 8 ]. The GALNT gene family, which initiates mucin-type O-glycosylation, is implicated in POI pathogenesis [ 95 ]. These enzymes are essential for the proper glycosylation of membrane-bound and secreted proteins in the ovary, a process vital for protein stability, signaling, and cell-cell interactions [ 96 , 97 ]. Disruptions in O-glycosylation due to aberrant GALNT function may impair key processes such as ovarian follicle maturation and hormonal signaling, thereby contributing to reproductive dysfunction and POI. While the specific mechanisms in POI require further elucidation, the fundamental role of O-glycosylation in cellular communication suggests that GALNT-mediated glycosylation defects are a plausible contributor to the pathophysiology of POI [ 98 ] Fig. 3 . Fig. 3 Key genes associated with glycosylation and their impact on premature ovarian insufficiency Key genes associated with glycosylation and their impact on premature ovarian insufficiency