4 weeks
CPT Code 
Test Code 
Test Methods 
Specimen Types Accepted 
Cultured Cells
Extracted DNA

The hallmark features seen in patients with OPHN1 mutations include moderate to severe mental retardation and cerebellar hypoplasia [OMIM #300486], particularly cerebellar vermis hypoplasia (CVH). CVH may also be called “Dandy-Walker variant” due to the phenotypic overlap with Dandy-Walker malformation (DWM). Physical findings may include tall stature, macrocephaly, and common facial features such as prominent supraorbital ridges, hypotelorism, deep-set eyes, long tubular nose, short philtrum, thin upper lip and prominent chin. Hypotonia and developmental delay are noticed in most patients in early childhood, who then develop moderate to severe mental retardation. Mutations of the OPHN1 [OMIM #300127] gene, or oligophrenin-1, have been identified in patients with X-linked mental retardation with cerebellar hypoplasia. Philip N, et al [2003] reported that 2/6 (33%) males with moderate mental retardation and CVH had mutations in OPHN1. Zanni G, et al [2005] found that 2/17 (12%) males with mental retardation and cerebellar anomalies had OPHN1 mutations. Sequencing of OPHN1 can be ordered as a single test, or as part of our Cerebellar Hypoplasia Panel, or our X-Linked and Comprehensive Intellectual Disability Panels. Please see our information sheets for more details.