Steroid-resistant nephrotic syndrome as the initial presentation of nail-patella syndrome: a case of a de novo LMX1B mutation.
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.
Division of Nephrology, Department of Medicine, Kyoto Prefectural University of Medicine, 465 Kajii-cho, Kamigyo-ku, Kyoto, 602-8566, Japan.
Tomohiro
T
Nakata
Division of Nephrology, Department of Medicine, Kyoto Prefectural University of Medicine, 465 Kajii-cho, Kamigyo-ku, Kyoto, 602-8566, Japan.
Ryo
R
Ishida
Division of Nephrology, Department of Medicine, Kyoto Prefectural University of Medicine, 465 Kajii-cho, Kamigyo-ku, Kyoto, 602-8566, Japan.
Yuu
Y
Mihara
Division of Nephrology, Department of Medicine, Kyoto Prefectural University of Medicine, 465 Kajii-cho, Kamigyo-ku, Kyoto, 602-8566, Japan.
Atsuko
A
Fujii
Division of Nephrology, Kyoto Min-iren Chuo Hospital, 16-1 Nishinokyo Kasuga-cho, Nakagyo-ku, Kyoto, 604-8453, Japan.
Yoshimoto
Y
Inoue
Division of Nephrology, Department of Medicine, Kyoto Prefectural University of Medicine, 465 Kajii-cho, Kamigyo-ku, Kyoto, 602-8566, Japan.
Tetsuro
T
Kusaba
Department of Pediatrics, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan.
Tsuyoshi
T
Isojima
Department of Pediatrics, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan.
Yutaka
Y
Harita
Division of Nephrology, Kyoto Min-iren Chuo Hospital, 16-1 Nishinokyo Kasuga-cho, Nakagyo-ku, Kyoto, 604-8453, Japan.
Chiaki
C
Kanda
Department of Pediatrics, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan.
Sachiko
S
Kitanaka
Division of Nephrology, Department of Medicine, Kyoto Prefectural University of Medicine, 465 Kajii-cho, Kamigyo-ku, Kyoto, 602-8566, Japan. tamagaki@koto.kpu-m.ac.jp.
Keiichi
K
Tamagaki
D000305:Adrenal Cortex Hormones / Q000627:therapeutic use; D005260:Female; D006801:Humans; D007668:Kidney / Q000473:pathology / Q000648:ultrastructure; D060850:LIM-Homeodomain Proteins / Q000235:genetics*; D009154:Mutation; D009261:Nail-Patella Syndrome / Q000150:complications / Q000175:diagnosis* / Q000235:genetics / Q000473:pathology; D009404:Nephrotic Syndrome / Q000175:diagnosis* / Q000188:drug therapy / Q000209:etiology / Q000235:genetics; D014157:Transcription Factors / Q000235:genetics*; D017211:Treatment Failure; D055815:Young Adult
D000305:Adrenal Cortex Hormones; C112149:LIM homeobox transcription factor 1 beta; D060850:LIM-Homeodomain Proteins; D014157:Transcription Factors
LMX1B; Nail-patella syndrome; Steroid-resistant nephrotic syndrome