Résumé
Nail-patella syndrome (NPS) is a hereditary rare disease that can involve fingernail, patella, elbow, and iliac bones. In this article, we report a case of a girl-9 and 1 quarter years old who had asthmatic contractures in both elbows, thumbnail hypoplasia in both hands, patellar dislocation of both knees, iliac angle protrusion of both sides, and scoliosis. Whole exome sequencing suggests the presence of a LMX1B NM_002316.4:c.706G > C(p.Ala236Pro) mutation. NPS is an autosomal dominant disease associated with gene mutation of LMX1B, which can be diagnosed by combining the patient′s clinical manifestations and genetic results. The treatment now only targets on symptoms, relieving the localized severe lesion but not cure right now.
Résumé
Objective:To analyze clinical data of 3 children with LMX1B-associated disease characterized by asymptomatic glomerular proteinuria, thus improving the recognition of asymptomatic proteinuria with genetic causes. Methods:Three patients with LMX1B-associated disease presented with prominent asymptomatic proteinuria diagnosed by the next-generation sequencing in Department of Pediatrics, Peking University First Hospital from April 2014 to October 2017 were included in this study.Clinical data, including renal and extrarenal manifestations, renal biopsy, and family history, were collected and retrospectively analyzed. Results:All 3 children were girls, the age of onset were 2 years, 1 year, and 4 years, respectively, and the diagnosis age were 11 years, 5 years and 6 years, respectively.All of them had glomerular proteinuria, and nephrotic-level proteinuria occurred in one patient.Microscopic hematuria was found in 2 patients.All of them had normal renal function.Only one patient underwent renal biopsy.Electron microscopy of the first time of biopsy revealed segmental thinning of the glomerular basement membrane.Re-biopsy 4 years later showed irregular thickening of the glomerular basement membrane, moth-eaten appearance and collagen fibrillar material deposition.No abnormalities of nails, limbs and joints were observed by physical examination.Two patients had a family history of renal disease.Conclusions:Genetic factors should be considered in children with obscure onset asymptomatic proteinuria without definite clinical causes.Genetic testing can help diagnose and guide treatment as early as possible.
Résumé
Nail-patella syndrome (NPS) is an autosomal dominant disease that typically involves the nails, knees, elbows and the presence of iliac horns. In addition, some patients develop glomerulopathy or adult-onset glaucoma. NPS is caused by lossof- function mutations in the LMX1B gene. In this study, phenotype-genotype correlation was analyzed in 9 unrelated Korean children with NPS and their affected family members. The probands included 5 boy and 4 girls who were confirmed to have NPS, as well as 6 of their affected parents. All of the patients (100%) had dysplastic nails, while 13 patients (86.7%) had patellar anomalies, 8 (53.3%) had iliac horns, 6 (40.0%) had elbow contracture, and 4 (26.7%) had nephropathy including one patient who developed end-stage renal disease at age 4.2. The genetic study revealed 8 different LMX1B mutations (5 missense mutations, 1 frame-shifting deletion and 2 abnormal splicing mutations), 6 of which were novel. Genotype-phenotype correlation was not identified, but inter- and intrafamilial phenotypic variability was observed. Overall, these findings are similar to the results of previously conducted studies, and the mechanism underlying the phenotypic variations and predisposing factors of the development and progression of nephropathy in NPS patients are still unknown.