17q11.2 Microduplication Syndrome

17q11.2 microduplication syndrome is characterized by dysmorphic features and intellectual deficit.

Epidemiology

It has been described in seven patients within one family.

Clinical description

There is a marked clinical heterogeneity between patients. Striking findings are intellectual deficit, early onset of baldness (15 years of age) and dental enamel hypoplasia. Craniofacial dysmorphic features include microcephaly, long midface, malar hypoplasia, sparse eyebrows and thin upper lip. Short stature is common.

Etiology

17q11.2 microduplication encompasses the NF1 region. This region is involved in the NF1 microdeletion syndrome (neurofibromatosis type 1, see this term). The microduplication was recently identified by microarray-based comparative genomic hybridization (array-CGH). The underlying mechanism may be non-allelic homologous recombination (NAHR). The study of pedigree suggests that this microduplication segregates within the family for at least two generations.

Genetic counseling

Two patients displayed a normal clinical presentation, suggesting an autosomal dominant pattern of inheritance with incomplete penetrance.