Summary

Nail-patella syndrome (NPS, OMIM: #161200), also known as Fong disease, hereditary osteo-onychodysplasia (HOOD), and Turner-Kieser syndrome, is a rare pleiotropic, multisystemic condition with an estimated incidence of 1 per 50,000. It is characterized mainly by developmental defects of dorsal limb structures due to symmetrical mesodermal and ectodermal abnormalities. It manifests as a classic clinical tetrad of distal digital abnormalities and fingernail dysplasia, which are typically bilateral and symmetrical, hypoplasia or absence of the patella, presence of iliac horns, and elbow deformities. It can also affect other structures (e.g., tendons, ligaments, and muscles), and may impact ophthalmic (glaucoma, increased ocular pressure and subsequent blindness), renal (nephropathy), neurological, orthopedic, and gastrointestinal systems. NPS can lead to sensorineural hearing loss and vasomotor problems [1,2]. Clinical manifestations vary greatly in frequency and severity. The prognosis is relatively good when clinical features are mild and cause no disability. However, serious and even life-threatening complications can occur. NPS is usually clinically diagnosed based on physical examination and radiological imaging. Genetic testing and renal biopsy can also assist in diagnosis confirmation.