Molecular genetic testing in clinical diagnostic assessments that demonstrate correlations in patients with autosomal...

Inherited retinal dystrophies (IRDs) are a group of retinal degenerative diseases presenting genetic and clinical heterogeneities, which have challenged the genetic and clinical diagnoses of IRDs. Genetic evaluations of patients with IRD might result in better clinical assessments and better management of patients.

To determine the genetic lesions with phenotypic correlations in patients with diverse autosomal recessive IRD using next-generation sequencing.

A cohort of 20 Chinese families affected with autosomal recessive IRD were recruited (with data on their detailed family history and on their clinical condition). To identify disease-causing mutations in the patients, the targeted sequence capture of IRD-relevant genes using 2 in-house-designed microarrays, followed by next-generation sequencing, was performed. Bioinformatics annotation, intrafamilial cosegregation analyses, in silico analyses, and functional analyses were subsequently conducted for the variants identified by next-generation sequencing.

The results of detailed clinical evaluations, the identification of disease-causing mutations, and the clinical diagnosis.

Homozygous and biallelic variants were identified in 11 of the 20 families (55%) as very likely disease-causing mutations, including a total of 17 alleles, of which 12 are novel. The 17 alleles identified here include 3 missense, 6 nonsense, 4 frameshift, and 4 splice site mutations. In addition, we found biallelic RP1 mutations in a patient with cone-rod dystrophy, which was not previously correlated with RP1 mutations. Moreover, the identification of pathogenic mutations in 3 families helped to refine their clinical diagnoses.

In this study, to our knowledge, many mutations identified in those known loci for autosomal recessive IRD are novel. Specific RP1 mutations may correlate with cone-rod dystrophy. Genetic evaluations with targeted next-generation sequencing might result in a better clinical diagnosis and a better clinical assessment and, therefore, should be recommended for such patients.