Pervasive developmental disorders and GABAergic system in patients with inverted duplicated chromosome 15

Pervasive developmental disorders are characterized by severe, pervasive impairment in several areas of development, with distorted communication skills and stereotypical behavior. Pervasive developmental disorders have a heterogeneous etiology related to brain damage, familial affective psychopathology, chromosomal abnormalities, or dysfunction of neuromodulators. Recently, it has been suggested that the GABRB3 gene, located within chromosome 15q11-13, is a candidate for pervasive developmental disorder. In inverted duplicated chromosome 15 syndrome, in which there is a small marker chromosome derived from inversion and duplication of the chromosome 15q11-q13 region, all patients present with pervasive developmental disorder. To further investigate a possible involvement of the gamma-aminobutyric acid (GABA)ergic system in the inverted duplicated chromosome 15 syndrome, we evaluated plasma levels of GABA and diazepam binding inhibitor in 6 patients with inverted duplicated chromosome 15 and in 8 subjects not affected by neurologic disease. Our findings do not seem to support this hypothesis as no significant differences were found in the GABA and diazepam binding inhibitor plasma levels between patients with inverted duplicated chromosome 15 and controls, but we must consider the possibility that a genetic abnormality of the GABA(A) receptor could be present in patients with inverted duplicated chromosome 15 and still not be reflected in an alteration in either GABA or diazepam binding inhibitor levels in plasma.