Nakata Tomohiro, Ishida Ryo, Mihara Yuu, Fujii Atsuko, Inoue Yoshimoto, Kusaba Tetsuro, Isojima Tsuyoshi, Harita Yutaka, Kanda Chiaki, Kitanaka Sachiko, Tamagaki Keiichi
Division of Nephrology, Department of Medicine, Kyoto Prefectural University of Medicine, 465 Kajii-cho, Kamigyo-ku, Kyoto, 602-8566, Japan.
Division of Nephrology, Kyoto Min-iren Chuo Hospital, 16-1 Nishinokyo Kasuga-cho, Nakagyo-ku, Kyoto, 604-8453, Japan.
BMC Nephrol. 2017 Mar 23;18(1):100. doi: 10.1186/s12882-017-0516-7.
Nail-patella syndrome (NPS) is an autosomal dominant disorder caused by mutations in the LMX1B gene and is characterized by nail dysplasia, skeletal abnormalities, and nephropathy. We herein report a case of steroid-resistant nephrotic syndrome (SRNS) prior to overt orthopedic symptoms in a patient with NPS.
A 24-year-old woman presented to our hospital with knee pain. She had poorly developed nails, hypoplastic patellas, dislocation of the elbows, and iliac horns in the pelvis. At the age of 7, she developed nephrotic syndrome and was diagnosed with primary focal segmental glomerulosclerosis by renal biopsy. She received long-term corticosteroid therapy with no obvious response. Her clinical course and orthopedic manifestations indicated NPS, and a genetic analysis showed a de novo mutation in the LMX1B gene (c.819 + 1G > A). Nephropathy in this case was considered to be associated with NPS. Therefore, we discontinued corticosteroids without the exacerbation of nephrotic syndrome.
Patients with NPS may develop nephrotic syndrome prior to overt orthopedic symptoms and only show non-specific findings in renal biopsy at an early stage of NPS nephropathy. Hereditary nephrotic syndrome, often presenting as childhood-onset SRNS, may also be difficult to diagnose in patients with the following conditions: renal symptoms prior to overt extrarenal symptoms, de novo mutations, and non-specific findings in renal biopsy. Therefore, in the management of SRNS in children, we need to reconsider the possibility of hereditary diseases such as NPS even without a family history.
指甲-髌骨综合征（NPS）是一种由LMX1B基因突变引起的常染色体显性疾病，其特征为指甲发育异常、骨骼畸形和肾病。我们在此报告1例NPS患者在出现明显骨科症状之前发生类固醇抵抗性肾病综合征（SRNS）的病例。
一名24岁女性因膝关节疼痛前来我院就诊。她有指甲发育不良、髌骨发育不全、肘部脱位以及骨盆髂骨角。7岁时，她患上肾病综合征，经肾活检诊断为原发性局灶节段性肾小球硬化。她接受了长期皮质类固醇治疗，但无明显反应。她的临床病程和骨科表现提示NPS，基因分析显示LMX1B基因存在新发突变（c.819+1G>A）。该病例中的肾病被认为与NPS相关。因此，我们停用了皮质类固醇，肾病综合征未加重。
NPS患者可能在出现明显骨科症状之前就发生肾病综合征，且在NPS肾病早期肾活检仅显示非特异性结果。遗传性肾病综合征常表现为儿童期发病的SRNS，对于有以下情况的患者也可能难以诊断：肾外症状出现之前的肾脏症状、新发突变以及肾活检中的非特异性结果。因此，在儿童SRNS的管理中，即使没有家族史，我们也需要重新考虑诸如NPS等遗传性疾病的可能性。
