Laboratory Studies

See the list below:

Annual screening urinalysis with microscopy is indicated in patients with nail-patella syndrome (NPS) to evaluate for proteinuria and hematuria. A urine protein-to-creatinine ratio or albumin-to-creatinine ratio is also indicated.
Annual blood pressure measurements and annual BUN and creatinine level assessments are indicated.
Consider 24-hour urine collection to quantitate protein and creatinine excretion if above screening results are abnormal.
LMX1B sequencing is diagnostic in the majority of patients.^{[11, 12, 13]} LMX1B mutations in exons 2-6 can be found via DNA sequencing in 80-85% of patients with nail-patella syndrome, and an additional 5% can be picked up with deletion and duplication analysis. Once a mutation is found, other family members can have targeted testing.

Imaging Studies

See the list below:

Radiography may reveal iliac horns, hypoplastic patellae, or abnormal radial heads.
If joint surgery planned, conduct MRI of that joint to identify abnormal tendon, ligament, and/or muscle insertions and vessel distribution prior to surgery. Anatomy of joints in patients with nail-patella syndrome is typically abnormal.

Other Tests

See the list below:

Perform annual dilated ophthalmologic examination including slit-lamp quantification of intraocular pressure and visual fields.
Consider dual energy x-ray absorptiometry (DEXA) scanning to evaluate bone mineral content and density as surrogate indicator of bone strength. Bone mineral density is decreased by 8-20% in the hips of patients with nail-patella syndrome, and increased fractures have been reported.

Procedures

See the list below:

Renal biopsy may be indicated after referral to nephrologist for evaluation of progressive renal insufficiency, proteinuria, and hypertension in nail-patella syndrome.
Light microscopy reveals glomerulonephritis and basement membrane thickening; however, negative results do not rule out pathologic processes in the kidney.
Electron microscopy can reveal ultrastructural changes, such as irregularities and thickening of the basement membrane and the presence of collagen-like fibrils within the basement membrane, which cannot be seen with light microscopy. These appearances are pathognomonic.

Histologic Findings

See the list below:

Increased lucency of the glomerular basement membrane resembles a moth-eaten appearance. A typical lesion consists of irregular basement membrane thickening, epithelial foot process fusion, and the presence of fibrillar collagenlike material within the basement.
Histological features are present even in patients without clinically evident renal involvement.

Treatment & Management

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Media Gallery

Nail of a patient the nail-patella syndrome.
Decreased severity of nail dystrophy towards the fifth finger and loss of skin creases over the distal interphalangeal joints. Courtesy of Journal of Medical Genetics, BMJ Publishing Group Ltd.
Triangular lunules. Courtesy of Journal of Medical Genetics, BMJ Publishing Group Ltd.
X-ray of pelvis showing iliac horns. Courtesy of Journal of Medical Genetics, BMJ Publishing Group Ltd.
X-ray of pelvis showing iliac horns in early childhood. Courtesy of Journal of Medical Genetics, BMJ Publishing Group Ltd.
Lester's sign of the iris. Courtesy of Journal of Medical Genetics, BMJ Publishing Group Ltd.

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Author

Julie Hoover-Fong, MD, PhD, FACMG Professor, Department of Genetic Medicine, Director, Greenberg Center for Skeletal Dysplasias, McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine

Julie Hoover-Fong, MD, PhD, FACMG is a member of the following medical societies: American College of Medical Genetics and Genomics, American Society of Human Genetics, International Skeletal Dysplasia Society

Disclosure: Nothing to disclose.

Coauthor(s)

Iain McIntosh, PhD President, Bendel Camus Medical Education, Inc

Iain McIntosh, PhD is a member of the following medical societies: American Society of Human Genetics

Disclosure: Nothing to disclose.

Elizabeth Sweeney, MBChB, MD Consultant Clinical Geneticist, Royal Liverpool Children’s Hospital, UK

Elizabeth Sweeney, MBChB, MD is a member of the following medical societies: British Society of Human Genetics

Disclosure: Nothing to disclose.

Specialty Editor Board

Mary L Windle, PharmD Adjunct Associate Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference

Disclosure: Nothing to disclose.

Lois J Starr, MD, FAAP Assistant Professor of Pediatrics, Clinical Geneticist, Munroe Meyer Institute for Genetics and Rehabilitation, University of Nebraska Medical Center

Lois J Starr, MD, FAAP is a member of the following medical societies: American Academy of Pediatrics, American College of Medical Genetics and Genomics

Disclosure: Nothing to disclose.

Chief Editor

Maria Descartes, MD Professor, Department of Human Genetics and Department of Pediatrics, University of Alabama at Birmingham School of Medicine

Maria Descartes, MD is a member of the following medical societies: American Academy of Pediatrics, American College of Medical Genetics and Genomics, American Medical Association, American Society of Human Genetics, Society for Inherited Metabolic Disorders, International Skeletal Dysplasia Society, Southeastern Regional Genetics Group

Disclosure: Nothing to disclose.

Additional Contributors

Christian J Renner, MD Consulting Staff, Department of Pediatrics, University Hospital for Children and Adolescents, Erlangen, Germany

Disclosure: Nothing to disclose.

Acknowledgements

The authors and editors of Medscape Reference gratefully acknowledge the contributions of previous authors Suzanne M Carter, MS, and Susan J Gross, MD, FRCS(C), FACOG, FACMG, to the original writing and development of this article.