Microduplications in 22q11.2 and 8q22.1 associated with mild mental retardation and generalized overgrowth.

ABSTRACT

The 22q11.2 microduplication is a genomic disorder, characterized from a variable phenotype ranging from different defects to normality. The most common microduplication of 22q11.2 is 3 Mb in size, but there are also cases reported with atypical duplications between 0.8 Mb and 6Mb. Here, we describe a case of a child with macrocephaly, overgrowth with advanced bone age, attention deficits, evidence of mild mental retardation and dysmorphic features. An array-CGH analysis detected a 252 Kb duplication at the 22q11.2 region inherited from mother and 142 Kb duplication at 8q22.1 region inherited from father. Both parents show mild dysmorphic features. The duplicated genes in chromosomes 22q and 8q are TOP3B and PGCP, respectively. We describe for the first time a patient carrying the smaller atypical 22q11.2 duplication who also presents with mild mental retardation and generalized overgrowth. This patient has an additional duplication in 8q22.1 which may act as a genomic modifier of its clinical phenotype.