3q29 Microduplication Syndrome

3q29 microduplications are recently described chromosomal abnormalities with unclear clinical significance.

Epidemiology

They have been reported in fewer than 30 patients.

Clinical description

The clinical phenotype is extremely variable and the most consistent features are mild or moderate intellectual deficit and microcephaly.

Etiology

Among duplications, only some appear to be the reciprocal duplication products of 3q29 microdeletion (see this term) and the others flank, span, or partially overlap the common deletion region. These results suggest that other mechanisms in addition to non-allelic homologous recombination (NAHR) mediate rearrangements of 3q29. These microduplications appear de novo or are inherited from mildly affected or completely normal parents. The clinical significance of reciprocal 3q29 microduplication is still unclear.