Nail-patella syndrome: report of 11 pediatric cases.

Background: Nail-patella syndrome (NPS) is an inherited disease produced by mutations in the LMX1B gene. It is characterized by fingernail dysplasia, hypoplastic or absent patella, dysplasia of the elbows and iliac horns on X-ray. It is useful to know this syndrome since some patients develop nephropathy and eye abnormalities. There are very few accurate descriptions related to this syndrome in the literature.

Objective: Describe the features of 11 patients with NPS in a paediatric hospital.

Methods: We retrospectively reviewed our clinical database of 11 patients with proven diagnosis of NPS from 1977 to 2014. Clinical and radiological features were assessed.

Results: Eleven children (seven male/four female) were included in the study. Mean age at the time of diagnosis was 6.54 years (range 0-11 years). Five patients had a family history of NPS. All patients had nail abnormalities (100%), the most frequent finding being hyponychia. Triangular lunulae were observed in four patients. The knee was the most commonly affected joint, aplasia or hypoplasia of the patella being the most usual findings. Only one patient presented renal involvement. The genetic study revealed three different LMX1B mutations.

Conclusion: Nail-patella syndrome is a rare disorder. The aim of the present study is to highlight the importance of nail examination in children with skeletal dysplasias, in order to diagnose the NPS.