[Phenotypic variability of the 1q21.1 microdeletion syndrome in members of the same family: relevance of detection of neuropsychiatric disorders for diagnosis of genetic syndromes].

Introduction: 1q21.1 microdeletion syndrome is a caused by a recurrent deletion of the 1q21.1 copy-number variant, which spans 800 kb and includes at least seven genes. It is associated with a variable phenotype. Neuropsychiatric abnormalities have been previously described in many of the previously reported cases, but its true prevalence is unknown.

Aim: To illustrate the phenotypic variability in 1q21.1 microdeletion syndrome.

Case Reports: Four individuals of the same kindred harboring a 1.74-Mb deletion within 1q21.1 are included. In our patients a heterogeneous phenotype is recognized. Neuropsychiatric disorders or more specifically impulse control disorders were common to all the four cases that we present.

Conclusions: 1q21.1 microdeletion syndrome is phenotypically heterogeneous even among members of the same family. Behavioral or neuropsychiatric abnormalities are frequent. Paucisymptomatic forms with individuals presenting exclusively psychiatric disorders have been identified.