PHARC syndrome which an ultra-rare syndrome with retinitis pigmentosa and cataracts: case report and review of the literature.

Background: PHARC syndrome (MIM:612674) is a rare neurodegenerative disorder characterized by demyelinating polyneuropathy, hearing loss, ataxia, retinitis pigmentosa, and cataracts (PHARC). The syndrome is caused by mutations in the ABHD12 gene, which encodes αβ-hydrolase domain-containing protein 12 related to endocannabinoid metabolism. PHARC syndrome is one of the rare diseases; so far, only 51 patients have been reported in the literature.

Methods: We evaluated the 25-year-old male patient referred to us due to vision loss, cataracts, and hearing loss. Ophthalmological examinations and genetic analyses were performed using targeted next-generation sequencing.

Results: In the genetic analysis, the patient was diagnosed with PHARC syndrome by detecting homozygous (NM_001042472.3): c.871del (p.Tyr291IlefsTer28) novel pathogenic variation in the ABHD12 gene. Following the molecular diagnosis, he was referred to the neurology department for reverse phenotyping and sensorimotor demyelinating polyneuropathy was detected in the neurological evaluation.

Conclusions: In this study, we report a novel variation in ABHD12 gene in the first Turkish-origin PHARC patient. We present this study to contribute genotype-phenotype correlation of PHARC syndrome and emphasize the importance of molecular genetic diagnosis in order to determine the appropriate clinical approach. This report is essential for expanding the phenotypic spectrum in different populations and understanding the genotype-phenotype correlation of PHARC syndrome via novel pathogenic variation in the ABHD12 gene.