ObjectiveTo identify two pathogenic gene mutations in two families with Alström syndrome (ALMS). MethodsA retrospective clinical study. Two patients and five family members from two Han families of ALMS diagnosed at Henan Eye Hospital from August 2020 to December 2021 were enrolled in this study. All participants underwent comprehensive ophthalmic examinations including best corrected visual acuity (BCVA), color test, slit-lamp, fundus biomicroscopy with slit lamp, fundus color photography, optical coherence tomography (OCT) and full-field electroretinography (ff-ERG) after the detailed history of the patient was taken. Five millilitres peripheral venous blood of each subject was collected, and the whole genome DNA was extracted. The pathogenic genes and mutation sites were identified using whole exome sequencing and the identified mutations were verified by Sanger sequencing. Mutation sites were analyzed via bioinformatics softwares. ResultsFamily one included one victim and two members and family two included one victim and three members. Proband in the first family was a four-year old boy whose chief complaint was poor vision along with photophobia since born, while proband in the second family was a 12-year old girl whose chief complaint was the same. The boy proband could not distinguish color, and both the anterior segment and fundus were normal. Ellipsoid zone of the boy was unclear in both eyes in OCT, and though rod system function decreased mildly-moderately in both eyes, the cone system function decreased severely in ff-ERG. The girl could not distinguish color as well, and the anterior segment was normal, though obvious pigmentary change could be seen in both retinas. The integrity of outer retinal bands was unclear in both eyes in OCT, and both cone and rod systems function decreased severely in both eyes in ff-ERG. Gene tests and bioinformatics analyze showed c.468dupT and c.10819C>T of ALMS1 gene in family one were novel mutations and c.10819C>T in family one and c.10831_10832del in family two were pathogenic mutations. ConclusionsM1, M2 and M3, M4 may be pathogenic gene variants in family 1 and family 2, respectively. The compound heterozygous mutation, c.468dupT and c.10819C>T of ALMS1 gene was a novel mutation.
ObjectiveTo determine the pathogenic gene mutation in a family with incomplete congenital quiescent night blindness (CSNB) of Schubert-Bornschein type. MethodsA retrospective clinical study. In February 2021, one patient and his parents and elder brother from a Han Chinese incomplete CSNB of Schubert-Bornschein type family diagnosed by clinical and genetic examination at Henan Provincial People's Hospital were included in the study. The patient’s medical history, family history were inquired; best corrected visual acuity (BCVA), color vision, fundus color photography, full-field electroretinogram (ERG), and frequency domain optical coherence tomography (OCT) were examined in detail. Five ml of the subject’s peripheral venous blood was collected and the whole genome DNA was extracted. The genomic DNA of the subject was library constructed, and all-exon probes were polymerized for capture. The suspected pathogenic mutation site was verified by Sanger, and the pathogenicity of the gene mutation site was determined by parallel bioinformatics analysis. ResultsThe BCVA of both eyes of the proband (Ⅱ2) was 0.4; the color vision test could not recognize the red color. Fundus examination showed no obvious abnormalities. The retina thickness in the macular area of both eyes was slightly thinned. ERG examination of the whole field showed that the amplitude of ERG b wave was significantly reduced under the stimulation of binocular dark adaptation 3.0 and showed a negative waveform. The mother of the proband (Ⅰ2) had normal BCVA, color vision, fundus color photography, and frequency domain OCT examination. The full-field ERG examination showed that the amplitude of each eye reaction was slightly reduced, and the amplitude of the dark adaptation shock potential was significantly reduced. Genetic testing showed that the proband (Ⅱ2) had a c.1761dupC hemizygous mutation in exon 14 of the voltage-dependent calcium channel α1F subunit gene (CACNA1F gene). The results of protein sequence homology analysis showed that the site was highly conserved in multiple species; the results of bioinformatics analysis showed that the CACNA1F gene c.1761dupC (pY588fs) subsequently had a frameshift mutation and became a stop at position 10. Codons appear translational termination in the conserved regions of the protein. According to the standards and guidelines of the American College of Medical Genetics and Genomics, the mutation was judged to be a possible pathogenic variant. The mother of the proband (Ⅰ2) was a carrier of this site mutation. The clinical and genetic test results of the father and elder brother of the proband were not abnormal. ConclusionCACNA1F gene c.1761dupC is the pathogenic mutation site of the Schubert-Bornschein type incomplete CSNB family.