GPR126: A novel candidate gene implicated in autosomal recessive intellectual disability.

Intellectual disability (ID), a genetically and clinically heterogeneous disorder, affects 1%-3% of the general population and is a major health problem, especially in developing countries and in populations with a high frequency of consanguineous marriage. Using whole exome sequencing, a homozygous missense variation (c.3264G>C, p.W1088C) in a plausible disease causing gene, GPR126, was identified in two patients presenting with profound ID, severe speech impairment, microcephaly, seizures during infancy, and spasticity accompanied by cerebellar hypoplasia. The role of GPR126 in radial sorting and myelination in Schwann cells suggests a mechanism of pathogenesis for ID. Involvement of GPR126 in lethal congenital contracture syndrome 9 has been identified previously, but this is the first report of a plausible candidate gene, GPR126, in ID.