Alternative titles; symbols
SNOMEDCT: 236527004; ORPHA: 2613;
| Location | Phenotype |
Phenotype MIM number |
Inheritance |
Phenotype mapping key |
Gene/Locus |
Gene/Locus MIM number |
|---|---|---|---|---|---|---|
| 9q33.3 | Focal segmental glomerulosclerosis 10 | 256020 | Autosomal dominant | 3 | LMX1B | 602575 |
A number sign (#) is used with this entry because of evidence that focal segmental glomerulosclerosis-10 (FSGS10), also referred to as nail-patella-like renal disease (NPLRD), is caused by heterozygous mutation in the LMX1B gene (602575) on chromosome 9q34.
Heterozygous mutation in the LMX1B gene can also cause nail-patella syndrome (NPS; 161200). About 30 to 50% of patients with NPS develop a nephropathy similar to FSGS10 (Pinto e Vairo et al., 2020).
Focal segmental glomerulosclerosis-10 (FSGS10) is an autosomal dominant kidney disease characterized by isolated glomerulopathy without extrarenal manifestations. In particular, affected individuals do not have other signs of NPS. The renal disease is highly variable in severity and pathology, even within the same family. Most patients present in the first decades of life with proteinuria and hematuria, although onset of symptoms can manifest at any age, including late adulthood. Some patients progress to end-stage renal disease, whereas others have a stable disease course. Light microscopic analysis of renal biopsies shows a constellation of glomerular abnormalities, including focal segmental glomerulosclerosis (FSGS), minimal change disease (MCD), and, rarely, immune complex nephropathy. Electron microscopy characteristically shows an irregular thickening of the glomerular basement membrane (GBM) with electron-lucent areas containing accumulated bundles of type III collagen fibrils. The collagen deposition usually occurs in endothelial cells of the GBM; partial effacement of podocyte foot processes may also be present. These specific pathologic findings are similar to those observed in NPS patients with nephropathy. However, these findings may not always be present, which may make the diagnosis challenging (summary by Hall et al., 2017, Lei et al., 2020; review by Harita et al., 2017).
For a discussion of genetic heterogeneity of FSGS, see FSGS1 (603278).
Dombros and Katz (1982) reported a 34-year-old woman who was found to have microscopic hematuria on routine examination. Renal biopsy showed mostly normal results on light microscopy, but electron microscopy showed localized areas of GMB widening and pallor on the endothelial aspect as well as collagen fiber deposition in the mesangial matrix. These findings were similar to the typical renal pathologic changes in NPS, but the patient and her close relatives had no signs or symptoms of NPS.
Zuppan et al. (2003) reported a 17-year-old boy who presented with chronic hematuria and nonnephrotic proteinuria without renal insufficiency. He had no skeletal or joint abnormalities or dystrophic nail changes, and there was no family history of a similar disorder. Renal biopsy showed mild and nonspecific changes on routine light examination, whereas there was effacement of podocyte foot processes and collagen deposition within capillary wall basement membranes in the glomeruli, typical for NPS. The renal disease was stable at last follow-up.
Boyer et al. (2013) reported a large multigenerational family of European descent (family F) in which 10 individuals spanning 4 generations had chronic progressive kidney disease. The phenotype was highly variable. Two index patients presented with nephrotic-range proteinuria at 6 and 26 years of age. Renal function was normal, but biopsy showed FSGS. Other affected family members had various degrees of glomerular proteinuria detected between 22 and 70 years of age. Several had chronic kidney disease, including progression to end-stage renal disease. At least 1 patient had a kidney transplant, at age 60 years. Renal biopsy, performed on 3 patients, showed FSGS. Electron microscopy was performed in only 1 patient, but did not show the characteristic thickening of the GBM that is usually observed in patients with NPS nephropathy. None of the patients had any extrarenal symptoms, particularly no signs or symptoms of NPS. The findings indicated that renal biopsy in patients with LMX1B mutations may not always show the usual abnormalities, which makes the diagnosis challenging. The authors also identified 2 smaller families (families V and B) with a similar disorder. The probands of these families were diagnosed with nephrotic syndrome at 22 and 5 years of age, respectively. Renal biopsy showed FSGS in 1 family and minimal change disease in the other. There were no extrarenal manifestations.
Isojima et al. (2014) reported a 6-year-old Japanese girl who was found incidentally to have mild proteinuria and microscopic hematuria. She had normal nails, patellae, and elbows, with no signs of NPS. Renal biopsy showed normal glomeruli on light microscopy with no immunoglobulin or complement deposition. Electron microscopic analysis showed moderate effacement of podocyte foot processes and irregular thickening of the GBM, which had a moth-eaten appearance and contained fibrillar material composed of type III collagen. The findings were diagnostic for NPLRD.
Lei et al. (2020) reported 2 unrelated families of Hispanic descent with autosomal dominant nephropathy manifest as proteinuria, microscopic hematuria, and hypertension. None had extrarenal manifestations or signs of NPS. Renal biopsies were notable for podocyte myelin figures and zebra bodies, multilamellar inclusions observed by electron microscopy. These features are usually seen in Fabry disease (301500), but that diagnosis was excluded. Reevaluation of patient renal biopsies after genetic analysis did not show irregular thickening of the GBM; only 1 patient had some focal irregular curvilinear collagen fibrils. Lei et al. (2020) emphasized the potential diagnostic pitfalls that may occur in the absence of unique GBM changes usually associated with LMX1B mutations.
Pinto e Vairo et al. (2020) reported a 65-year-old woman with a long-standing history of chronic renal disease, proteinuria, and hypertension associated with FSGS and focal myelin figures within podocytes on renal biopsy. Repeat biopsy confirmed FSGS and also showed podocyte foot effacement with some myelin figures and zebra bodies. No beaded collagen fibers were observed in the GBM. The patient underwent renal transplantation. Fabry disease was excluded. She had no extrarenal signs of NPS.
The transmission pattern of FSGS10 in the families reported by Boyer et al. (2013) was consistent with autosomal dominant inheritance. Penetrance is complete, but expressivity is highly variable (Lei et al., 2020).
In 5 affected members of a large multigenerational family (family F) with FSGS10, Boyer et al. (2013) identified a heterozygous missense mutation in the LMX1B gene (R246Q; 602575.0014). The mutation, which was found by a combination of linkage analysis and exome sequencing, segregated with the disorder in the family. Direct sequencing of the LMX1B gene in a cohort of 73 unrelated families with a similar phenotype identified a heterozygous R246Q mutation in an affected mother and daughter (family V) and a heterozygous R246P (602575.0015) mutation in an affected father and daughter (family B). Neither variant was present in the Exome Sequencing Project database. Functional studies of the variants and studies of patient cells were not performed, but Boyer et al. (2013) noted that residue R246 is highly conserved and located in the homeobox domain, which is important for DNA binding and transcriptional activation.
In a 6-year-old Japanese girl with FSGS10, Isojima et al. (2014) identified a de novo heterozygous R246Q substitution in the LMX1B gene. The mutation, which was found by direct sequencing of the LMX1B gene, was not present in the dbSNP database or among Japanese controls. In vitro functional expression studies showed that the mutation partially impaired transcriptional activity of LMX1B compared to controls, but not to the extent as mutations associated with NPS. There was no evidence for a dominant-negative effect, and the authors postulated haploinsufficiency. Renal biopsy from the patient showed podocyte effacement, a thickened glomerular basement membrane (GBM) due to abnormal deposition of type III collagen, and altered expression of CD2AP (604241), which plays a role in podocyte development and cytoskeleton remodeling.
In 18 affected members from 2 large multigenerational families (DUK35705 and DUK34319) with FSGS10, Hall et al. (2017) identified a heterozygous R246Q mutation in the LMX1B gene. The mutation, which was found by a combination of linkage analysis and whole-exome sequencing and confirmed by Sanger sequencing, segregated with the disorder in both families. In vitro functional expression studies in human podocyte cell lines transfected with the mutation showed altered expression of certain key podocyte genes, suggesting that the mutation may exert a haploinsufficiency effect on the transcriptional regulation of these genes. However, additional studies indicated that the R246Q mutation exerted a dominant-negative effect on certain WT1 (607102) isoforms, which may have also caused alterations in the expression of podocyte-related genes. Hall et al. (2017) noted that the renal glomerular phenotype observed in these patients includes a wide variety of light microscopic findings, including FSGS, minimal change disease, membranous nephropathy, and even immune complex glomerulonephritis.
A heterozygous R246Q mutation was identified in patients with FSGS10 by Lei et al. (2020) and Pinto e Vairo et al. (2020).
Salcedo (1984) described a family in which 3 children of first-cousin parents of Palestinian Arab ancestry had proteinuria and renal impairment from an early age. Two of the sibs died at ages 6 and 7 years of end-stage renal disease. Renal biopsy in the proband showed the histopathologic electron microscopic changes of the nail-patella syndrome (161200); however, none of the family had bone or nail changes of this disorder. An autosomal recessive nephropathy or glomerulodysplasia was suggested.
Boyer, O., Woerner, S., Yang, F., Oakeley, E. J., Linghu, B., Gribouval, O., Tete, M.-J., Duca, J. S., Klickstein, L., Damask, A. J., Szustakowski, J. D., Heibel, F., and 10 others. LMX1B mutations cause hereditary FSGS without extrarenal involvement. J. Am. Soc. Nephrol. 24: 1216-1222, 2013. [PubMed: 23687361] [Full Text: https://doi.org/10.1681/ASN.2013020171]
Dombros, N., Katz, A. Nail patella-like renal lesions in the absence of skeletal abnormalities. Am. J. Kidney Dis. 1: 237-240, 1982. [PubMed: 7158631] [Full Text: https://doi.org/10.1016/s0272-6386(82)80060-7]
Hall, G., Lane, B., Chryst-Ladd, M., Wu, G., Lin, J.-J., Qin, X., Hauser, E. R., Gbadegesin, R. Dysregulation of WTI (-KTS) is associated with the kidney-specific effects of the LMX1B R246Q mutation. Sci. Rep. 7: 39933, 2017. Note: Electronic Article. [PubMed: 28059119] [Full Text: https://doi.org/10.1038/srep39933]
Harita, Y., Kitanaka, S., Isojima, T., Ashida, A., Hattori, M. Spectrum of LMX1B mutations: from nail-patella syndrome to isolated nephropathy. Pediat. Nephrol. 32: 1845-1850, 2017. [PubMed: 27450397] [Full Text: https://doi.org/10.1007/s00467-016-3462-x]
Isojima, T., Harita, Y., Furuyama, M., Sugawara, N., Ishizuka, K., Horita, S., Kajiho, Y., Miura, K., Igarashi, T., Hattori, M., Kitanaka, S. LMX1B mutation with residual transcriptional activity as a cause of isolated glomerulopathy. Nephrol. Dial. Transplant. 29: 81-88, 2014. [PubMed: 24042019] [Full Text: https://doi.org/10.1093/ndt/gft359]
Lei, L., Oh, G., Sutherland, S., Abra, G., Higgins, J., Sibley, R., Troxell, M., Kambham, N. Myelin bodies in LMX1B-associated nephropathy: potential for misdiagnosis. Pediat. Nephrol. 35: 1647-1657, 2020. [PubMed: 32356190] [Full Text: https://doi.org/10.1007/s00467-020-04564-w]
Pinto e Vairo, F., Pichurin, P. N., Fervenza, F. C., Nasr, S. H., Mills, K., Schmitz, C. T., Klee, E. W., Herrmann, S. M. Nail-patella-like renal disease masquerading as Fabry disease on kidney biopsy: a case report. BMC Nephrol. 21: 341, 2020. Note: Electronic Article. [PubMed: 32791958] [Full Text: https://doi.org/10.1186/s12882-020-02012-3]
Salcedo, J. R. An autosomal recessive disorder with glomerular basement membrane abnormalities similar to those seen in the nail patella syndrome: report of a kindred. Am. J. Med. Genet. 19: 579-584, 1984. [PubMed: 6507504] [Full Text: https://doi.org/10.1002/ajmg.1320190321]
Zuppan, C. W., Weeks, D. A., Cutler, D. Nail-patella glomerulopathy without associated constitutional abnormalities. Ultrastruct. Pathol. 27: 357-361, 2003. [PubMed: 14708727]