Screening ofSPATA7in Patients with Leber Congenital Amaurosis and Severe Childhood-Onset Retinal Dystrophy Reveals Disease-Causing Mutations

Abstract

To investigate the prevalence of sequence variants in the gene SPATA7 in patients with Leber congenital amaurosis (LCA) and autosomal recessive, severe, early-onset retinal dystrophy (EORD) and to delineate the ocular phenotype associated with SPATA7 mutations. Patients underwent standard ophthalmic evaluation after providing informed consent. One hundred forty-one DNA samples from patients with LCA and EORD had been analyzed for mutations by using a microarray, with negative results. One additional patient underwent SPATA7 screening due to a region of autozygosity surrounding this gene. A further patient was screened who had a compatible ocular phenotype. The entire SPATA7 coding sequence was assayed, including the intron-exon junctions, by using a combination of direct DNA sequencing and high-resolution melting screening. Screening of SPATA7 identified several known and novel single-nucleotide polymorphisms (SNPs). Affected individuals from five unrelated families were identified to have coding changes. Clinical features demonstrated a severe infantile onset retinal dystrophy, similar to Leber congenital amaurosis. The retina had widespread retinal pigment epithelial atrophy, with minimal pigment migration into the neurosensory retina. Fundus autofluorescence imaging showed a parafoveal annulus of increased autofluorescence. High-definition optical coherence tomography showed preservation of the inner segment/outer segment junction at the fovea. Mutations in SPATA7 are a rare cause of childhood retinal dystrophy accounting for 1.7% of disease in this cohort. Affected patients present in infancy with severe visual loss, but may have some preservation of the photoreceptor structure in the central retina.