Prenatal genetic diagnosis in a fetus with tetrasomy 18p from maternal trisomy 18p: a case report

Background: Tetrasomy 18p syndrome is a very rare chromosomal disorder that is caused by the presence of isochromosome 18p.Most tetrasomy 18p cases are de novo cases,maternal origin trisomy 18p is a very rare condition.At present, only 4 cases of maternal origin trisomy 18p have been reported.This was the the fifth from maternal trisomy 18p,the mother has no apparent disease phenotype. Case presentation: We hereby report a case of a fetus with normal ultrasound features, the Karyotyping and Single Nucleotide Polymophism array (SNP array) confirmed tetrasomy 18p.The mother and grandfather are phenotypically normal and healthy,but with trisomy 18p was confirmed by conventional karyotyping and SNP array. Conclusions: : We report a family with an 18p trisomic mother and grandfather,18p tetrasomic fetus,the mother and grandfather are phenotypically normal. The findings could provide a reference for the genetic counseling of trisomy