A novel mutation of WDR62 gene associated with severe phenotype including infantile spasm, microcephaly, and intellectual disability.

The autosomal recessive form of primary microcephaly (MCPH) is a rare disorder characterized by head circumference of at least 3 standard deviation below the mean. The MCPH exhibits genetic heterogeneity with thirteen loci (MCPH1-MCPH13) identified, and associated with variable degree of intellectual disability. It has been reported that WDR62 is the second causative gene of autosomal recessive microcephaly (MCPH2) playing a significant role in spindle formation and the proliferation of neuronal progenitor cells. We report a clinical feature, electroclinical findings, and clinical course of a patient with a severe phenotype of MCPH2 including microcephaly, refractory infantile spasms and intellectual disability. Genetic analysis detected a new homozygous splicing variant c.3335+1G>C in the WD repeat domain 62 (WDR62) gene, inherited from both heterozygous healthy parents, and an additional new heterozygous missense mutation c.1706T>A of G protein-coupled receptor 56 (GPR56) gene inherited from his healthy father. The study seeks to broaden the knowledge of clinical and electroclinical findings of MCPH2 and to contribute to a better characterization of the genotype-phenotype correlation.