BCS1L pathogenic variants cause widely different clinical phenotypes. Disease phenotypes can be as mild as Björnstad syndrome, characterized by pili torti (abnormal flat twisted hair shafts) and sensorineural hearing loss, or as severe as GRACILE syndrome, characterized by growth restriction, aminoaciduria, cholestasis, iron overload, lactic acidosis and early death. BCS1L pathogenic variants are also linked to an undefined complex III deficiency, a heterogeneous condition generally involving renal and hepatic pathologies, hypotonia, and developmental delays. So far, all patients with GRACILE syndrome carry a homozygous p.Ser78Gly variant in BCS1L gene by reviewing articles. A 24-day-old boy presented with typical clinical phenotype of GRACILE syndrome. The Whole Exome Sequencing confirmed that the patient had a missense variant (c.245C > T, p.Ser82Leu) and a small deletion (c.231_232delCA, p. Ser78Cysfs*9) in BCS1L gene inherited from his father and mother separately, he died at 5 months of age. We reported a patient with GRACILE syndrome and identified two novel variants in BCS1L gene. Our study expands the mutational spectrum of BCS1L gene associated with GRACILE syndrome and will be beneficial for genetic diagnosis.
Bardet‐Biedl syndrome type 5 (BBS5) has never been reported in Chinese populations. The aim of this study is to report the first BBS5 case in China, explore the phenotype and genotype correlation. The case was male, Han nationality, born with polydactyly and gained weight after birth, accompanied by polydipsia, polyuria and nocturia. He was found to have low vision at the age of 7 years, and having insufficient renal function at the age of 20 years. After hospitalization, he was found to have suffered from atrophy of the whole layer of macular retina, and end stage of kidney disease, presenting with shrinking and cyst‐like changes of bilateral kidneys. Whole‐exome sequencing was performed among the proband and his parents (Trios), further validated using Sanger sequencing and quantitative polymerase chain reaction. Two novel compound heterozygous variants of BBS5 gene [a missense variant NC_000002.12, NM_152384.3:c.1A>G(p.Met1?) & a large deletion c.(?_‐60)_(386 + 1_387‐1)del] were detected. BBS is rare, whereas BBS5 is rarer. Herein, we reported a Chinese BBS5 patient with severe renal phenotype and identified two novel BBS5 variants.
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