Comprehensive analysis of pathogenic genes and clinical phenotypes in patients with Leber congenital amuarosis / 中华眼底病杂志

Objective:To observe clinical phenotypes and analyze the pathogenic genes of Leber congenital amaurosis (LCA).Methods:A retrospective clinical study. From 2019 to 2020, 2 patients diagnosed with LCA by genetic testing in Tianjin Medical University Eye Hospital and their 6 unaffected family members were enrolled in the study. Two patients were from 2 unrelated families, both were probands. The patient's medical history was inquired in detail, slit lamp microscopy, ultra-widefield fundus photography, autofluorescence, and flash visual evoked potential (F-VEP) were performed. Peripheral vein blood (3-5 ml) was collected and genomic DNA was extracted from all study subjects. A total of 381 pathogetic genes associated with inherited retinal diseases, were selected by targeted exome sequencing capture strategy. Sanger sequencing was used to verify suspected pathogenic mutations. Candidate pathogenic mutations were identified after bioinformatics analysis. Sanger sequencing, real-time quantitative polymerase chain reaction and family co-identification were used to confirm the final mutations.Results:Two patients were male, aged 3 and 27 years. One case had vision loss in both eyes, accompanied by nystagmus and acupressure eye sign since childhood. The clinical hallmark of the proband (F1-Ⅱ-3) in F1 includes clearly boundary of optic disc, normal retinal blood vessels and macular fovea. The implied period of the maximum forward wave in both eyes of F-VEP was roughly normal, and its amplitude decreased significantly. The phenotype of the proband (F2-Ⅱ-1) in F2 includes optic nerve head pallor, bone-spicule intraretinal pigmentation, "gold-foil maculopathy" , retina patchy hypo-autofluorescence in both eyes. There was no abnormal phenotype in the eyes of the family members. According to the genetic diagnosis, the proband (F1-Ⅱ-3) carried the GUCY2D gene c.835G>A (p.D279N) (M1) and exon 9-19 deletion (M2) compound heterozygous mutations, in which M1 was derived from healthy mother and M2 was derived from healthy father. The proband (F2-Ⅱ-1) carried CRB1 gene c.1576C>T(R526X) (M3) and c.1522T>C (C508R) (M4) compound heterozygous mutations, in which M3 from the healthy father, M4 from the healthy mother. M2 and M4 were novel mutations. Conclusion:GUCY2D gene mutations lead to LCA1 type in the F1 family, CRB1 gene mutations lead to LCA8 type in the F2 family; there are significant different phenotypes caused by different pathogenic genes.

Compound heterozygous mutations of CRB1 gene in a Chinese family with Leber congenital amaurosis by whole exome sequencing / 中华实验眼科杂志

Objective To investigate the disease-causing mutation in a family with Leber congenital amaurosis (LCA).Methods A Chinese Han pedigree with LCA from Chaoshan area was recruited in Shantou International Eye Center in August 2011.The clinical features of the families were evaluated,including medical history,best corrected visual acuity,intraocular pressure and fundus photography.The peripheral blood sample of 5 ml was collected from each of the family members for the extraction of genomic DNA.DNA of the proband was investigated by whole exome sequencing (WES) and was filtered for function of variants and inheritance pattern.Then,Sanger sequencing was performed to confirm the WES result on all the participating subjects in the pedigree.Results There were 11 families of 3 generations in this pedigree,and 2 female LCA patients were found (Ⅱ 2 and Ⅱ4) who were sisters.The parents (Ⅰ-1 and Ⅰ-2) and children (Ⅲ-1,Ⅲ-2,Ⅲ-3 and Ⅲ-4) of the patients showed normal phenotype,suggesting an autosomal recessive pattern.The patients appeared severe visual impairment during early childhood.Ophthalmic examination showed diffuse pigmentation on the retina and attenuation of retinal artery in both patients.WES of proband revealed two compound heterozygous mutations (c.2234C ＞T,p.T745M;c.3488G＞T,p.C1163F) of the CRB1 gene.Sanger sequencing confirmed the mutations in both patients (Ⅱ-2 and Ⅲ-4),and the parents of the patients were found to carry one mutations respectively and the other subjects with normal phenotype had neither none or only one mutation.Conclusions The compound heterozygous mutation of c.2234C＞ T,p.T745M and c.3488G＞T,p.C1163F in CRB1 is responsible for LCA pathogenesis this Chinese Han pedigree.

Concurrent retinitis pigmentosa and pigmented paravenous retinochoroidal atrophy phenotypes in the same patient.

We report a unique case of a patient with retinitis pigmentosa (RP) phenotype in one eye and pigmented paravenous retinochoroidal atrophy (PPRCA) phenotype in the other eye. We describe in detail the symptoms, clinical findings, and investigations done for a 32‑year‑old Indian woman. This patient had phenotypical picture resembling typical RP in the right eye, with characteristic symptoms of night blindness and constricted field of vision and a nonrecordable electroretinogram (ERG). The left eye of the same patient revealed typical PPRCA phenotype, with no night blindness, normal field, and normal ERG. RP and PPRCA phenotypes are part of the same spectrum of genetic disorder. However, it is rare to see them coexist in the same patient.