A homozygous deletion of 8q24.3 including the NIBP gene associated with severe developmental delay, dysgenesis of the corpus callosum, and dysmorphic facial features.

We have identified by microarray-based comparative genomic hybridization analysis (aCGH), a homozygous deletion of 8q24.3 [arr cgh 8q24.3(140,879,937 --> 141,021,392)x0 mat pat] in a patient with dysmorphic facial features, dysgenesis of the corpus callosum, and severe mental retardation. The deletion was inherited from asymptomatic, consanguineous parents, each of them being heterozygous for the same deletion. The only gene known to map to this segment is the NIBP gene, and so far no clinical manifestations have been found in association with this gene mutation in homozygous or heterozygous state in humans. Our findings suggest that a homozygous deletion in the NIBP gene results in an autosomal recessive condition with multiple abnormalities and severe delay. In addition, the child inherited a 781-kb deletion on 4q32.2 from the mother that contains the SPOCK3 gene. We suggest that this heterozygous deletion is likely to be non-contributory to the phenotype.