An Unbalanced de novo t(X;12)(q28;q15) in a Disabled Girl. Review of 25 (X;12) Translocations

We report on an unbalanced de novo (X;12) translocation and summarize the cytogenetic aspects of 25 similar exchanges here compiled. This translocation was found in an intellectually disabled girl and was characterized by means of G-bands and FISH assays with Xq/Yq and 12q subtelomeric probes. The patient’s karyotype was 46,X,der(X)t(X;12)(q28;q15).ish derX(Xq subtel–,12q subtel+) and entailed both a 12q15→qter duplication and a small Xq28 deletion. Among the 25 translocations here compiled, 10 were de novo, 5 maternally transmitted, and 10 of untraced origin. The paucity of (X;12) translocations probably reflects both the specificity of chromosomal domains and viability of imbalances.