5q35 Microduplication Syndrome

The newly described 5q35 microduplication syndrome is associated with microcephaly, short stature, developmental delay and delayed bone maturation.

Epidemiology

It has been reported in two unrelated patients.

Clinical description

There is no remarkable facial dysmorphism. The clinical picture is opposite to that of patients with Sotos syndrome (macrocephaly, overgrowth and advanced bone age; see this term).

Etiology

This microduplication was identified by microarray-based comparative genomic hybridization (aCGH). The breakpoints of the duplication in both patients map to the proximal and distal low-copy repeats (LCRs), which flank the Sotos critical region. These findings support a non-allelic homologous recombination (NAHR) as the mechanism of duplication, and a dosage effect of the Sotos gene NSD1 (5q35).