Nail-Patella Syndrome Workup

Updated: Feb 19, 2019
  • Author: Anna Choczaj-Kukula, MD, PhD; Chief Editor: Dirk M Elston, MD  more...
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Workup

Approach Considerations

A careful family history including pedigree should be obtained in all patients. [45, 99]

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Laboratory Studies

Urinalysis

Assess the urine albumin-to-creatinine ratio on a first morning urine sample. If any abnormalities are detected, refer to a nephrologist. These tests should be performed annually in all NPS patients. [37]

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Imaging Studies

Consider performing diagnostic imaging (radiography, CT scanning, MRI) to search for diagnostic and minor signs. [100] The distinct malformations of the knee in nail-patella syndrome (NPS) are recognizable on conventional radiographs. [101]

Dual-energy x-ray absorptiometry (DEXA) scanning should be considered in perimenopausal and postmenopausal females and older males with NPS. [37]

Diagnostic radiographic findings include the following [102, 103, 104] :

  • Hypoplastic patellae

  • Bilateral posterior iliac horns

  • Hypoplasia of the radial head or capitulum

The following findings are also reported:

  • Scapular hypoplasia

  • Scoliosis

  • Hypoplastic lateral humerus epicondyle

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Other Tests

Urine test with an annual microalbuminuria/creatinuria ratio is recommended.

Annual ophthalmological assessment is advised. Blood pressure monitoring and glaucoma screening should be performed. [37]

Molecular genetic testing to identify a pathogenic variant in the LMX1B gene may be useful to confirm the diagnosis in cases of mild or atypical phenotype in the proband or at-risk family members. [105, 106] Comprehensive genetic analysis may be useful for diagnosis of LMX1B-associated nephropathy. [107]

Prenatal diagnosis by molecular analysis can be offered when the mutation is known in the family, and evaluation of at-risk fetuses by three-dimensional ultrasound scan can be helpful in identifying the extent of associated abnormalities. [108]

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Procedures

In patients with proteinuria, percutaneous renal biopsy may be useful in evaluating renal involvement.

The features of nail-patella syndrome (NPS) nephropathy at light, immunofluorescence, and electron microscopy have been detailed, [17, 109] with an emphasis on the presence of characteristic ultrastructural collagen fibrils in the glomerular basement membrane.

Midline synovial septum completely subdividing the knee into medial and lateral compartments has been found during arthroscopy in patients with NPS. [110]

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Histologic Findings

The literature includes descriptions of numerous histologic abnormalities in the kidneys of patients with nail-patella syndrome (NPS). These findings include chronic glomerulonephritis, focal glomerular necrosis, diffuse hydropic degeneration of the tubular epithelium, and localized basement membrane thickening with mild proliferation of the endothelial and epithelial cells.

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