Disomy of distal Xq in males: Case report and overview

Abstract
A 46,XYq 8‐year‐old male was referred for microcephaly, growth, and mental retardation, hypotonia, genital hypoplasia, and dysmorphisms. FISH analysis showed that the rearranged Y chromosome originated from an unbalanced translocation of Xq27.3‐qter onto the deleted Yq11.22. Analysis of reported patients with disomy of region distal to Xq26 suggests that this rare anomaly, associated with failure to dosage compensate X‐linked genes that are normally inactivated, when present in two copies, is causing a quite distinct phenotype. This imbalance is the aberrant by product of the recombinogenic pairing of the distal pseudoautosomal Xq–Yq region at male meiosis.