A Novel Homozygous Deletion within the FRY Gene Associated with Nonsyndromic Developmental Delay

Abstract

The role of autosomal recessive (AR) variants in clinically heterogeneous conditions such as intellectual disability and developmental delay (ID/DD) has been difficult to uncover. Implication of causative pathogenic AR variants often requires investigation within large and consanguineous families, and/or identifying rare biallelic variants in affected individuals. Furthermore, detection of homozygous gene-level copy number variants during first-line genomic microarray testing in the pediatric population is a rare finding. We describe a 6.7-year-old male patient with ID/DD and a novel homozygous deletion involving the FRY gene identified by genomic SNP microarray. This deletion was observed within a large region of homozygosity on the long arm of chromosome 13 and in a background of increased low-level (2.6%) autosomal homozygosity, consistent with a reported common ancestry in the family. FRY encodes a protein that regulates cell cytoskeletal dynamics, functions in chromosomal alignment in mitosis in vitro, and has been shown to function in the nervous system in vivo. Homozygous mutation of FRY has been previously reported in 2 consanguineous families from studies of autosomal recessive ID in Middle Eastern and Northern African populations. This report provides additional supportive evidence that deleterious biallelic mutation of FRY is associated with ID/DD and illustrates the utility of genomic SNP microarray detection of low-level homozygosity.