Abstract: Objective · To identify the clinical features of a Chinese Han family with X-linked infantile nystagmus. Methods · A Chinese family with X-linked infantile nystagmus was recruited Department of Ophthalmology in Xinhua Hospital, Shanghai Jiao Tong University School of Medicine. Peripheral blood the members of the family was collected and molecular genetic analysis was done. The 5 patients in the family received comprehensive ocular examinations including measurement of visual acuity, degree of anomalous head posture, stereoscopic vision, binocular function, electroretinogram, visual evoked potential, optical coherence tomography, eye movement recording and cycloplegic refraction. Results · A frame-shift mutation (c.823-829delACCCTAC, p.Thr275fs) in the 9th exon of FERM domain containing protein 7 (FRMD7) in the family was found. The similar clinical features of the family included moderate impairment of visual acuity, mild astigmatism, reduced stereoscopic vision, no fusion function, and bidirectional jerk wave form. Their electroretinograms were normal, but there was a peak latency and decreased amplitudes in visual evoked potential. And the structures of maculae had no obvious abnormality. The performance of the anomalous head posture was varied. Conclusion · Thr275fs in FRMD7 protein is identified as the main factor in the Chinese family with X-linked infantile nystagmus. The clinical features of the family show a certain degree of consistency.

Key words: infantile nystagmus, FERM domain containing protein 7 (FRMD7), X-linked dominant inheritance, gene mutation, clinical characteristic