A novel frameshift c.22_25dupGCAT mutation of the NDP gene in a Chinese infant with Norrie disease: A case report

RATIONALE: Norrie disease (ND) is a rare X-linked recessive disease characterized by bilateral congenital blindness and auditory impairments. According to the previous studies, Norrin cystine knot growth factor (NDP) gene have been found to be responsible for ND. Herein, we report a case of ND with a novel mutation in NDP and elucidate the clinical and molecular characteristics of this patient. PATIENT CONCERNS: A 2-month-old Chinese male infant presented with gray-white opacification in the bilateral cornea. Vitreous opacity and retinal detachment were observed on ocular ultrasound. Furthermore, a novel de novo hemizygous mutation (c.22_25dupGCAT, p.S9Cfs∗18) in exon 2 of the NDP gene was identified by next-generation sequencing. SWISS-MODEL predicted that the c.22_25dupGCAT mutation truncated the NDP protein. DIAGNOSIS: Based on the above clinical and genetic evidence, this patient was eventually diagnosed with ND. INTERVENTIONS: Currently, no clinical therapy is available for ND. OUTCOMES: In addition to the typical ocular symptoms, no other abnormalities were observed. The patient's vital signs remained stable and normal. LESSON: A novel causative mutation of NDP was identified using next-generation sequencing. Our report expands the pathogenic mutation spectrum of NDP and facilitates genetic counseling and prenatal diagnosis. Additionally, we emphasize the importance of molecular genetic testing in the diagnosis of ND.