Novel variant causing OTUD6B-related syndrome with ocular dysplasia and hypothyroidism: the first Chinese case

Intellectual developmental disorder with dysmorphic facial features, seizures, and distal limb anomalies (IDDFSDA, MIM: #617452) is a rare autosomal recessive genetic disorder. There have been < 30 reported cases globally without fundus and retinal lesions.

Pathogenic gene variants were identified using whole exome trio sequencing (trioWES) and confirmed using Sanger sequencing. The literature on PubMed and Google Scholar was reviewed using the keyword "OTUD6B" to summarize and compare clinical phenotypes and OTUD6B variants in reported cases.

A 6-month-old girl presented with nystagmus and hypothyroidism. On admission, optic disc hypoplasia and retinal abnormalities were detected with a typical phenotype of IDDFSDA. TrioWES was used to identify compound heterozygous novel variants in the OTUD6B gene, namely c.479A > G and c.83-1delG. Significantly, none of the 27 previously reported IDDFSDA cases exhibited ocular developmental abnormalities.

OTUD6B defects correlate with multiple organ abnormalities, possibly including ocular developmental anomalies. Further investigation is required to investigate the association between the newly identified variants c.479A > G or c.83-1delG and ocular development.