Characteristic nails, especially of thumbs — as in the description above (the most common and recognizable feature of NPS, in about 95% patients). The skeletal structures of individuals who have this disorder may have pronounced deformities. As reported by several medical doctors, the following features are commonly found in people who with nail–patella syndrome: Bones and joints • Patellar involvement is present in approximately 75% of patients; however, patellar aplasia occurs in only 20%. • In instances in which the patellae are smaller or luxated, the knees may be unstable. • The knee joint may appear square. • Frequent
flat feet and/or other foot deformities. • The elbows may have limited motion (e.g., limited pronation, supination, extension). • Subluxation of the radial head may occur. • Arthrodysplasia of the elbows is reported in approximately 75% of patients. • Exostoses arising from the posterior aspect of the iliac bones ("iliac horns") are present in as many as 70–75% of patients; this finding is considered pathognomonic for the syndrome. • Other reported bone changes include
scoliosis,
scapular hypoplasia, and the presence of
cervical ribs. • A reduction in bone density, on average by about 8–20 %, which may lead to
osteoporosis. However, it is not certain whether the hypermobility results from a mutation of the same gene or a possibly accompanying mutation of some different gene. File:Nail-patella syndrome (NPS) Elbow1.JPG|An elbow of a man with nail–patella syndrome (NPS) File:Nail-patella Elbow2.JPG|This is a view from a different angle of the same man's other elbow File:Nail-patella.jpg|link=|alt= Glaucoma is also closely associated with nail-patella, specifically open-angled glaucoma (OAG). Side effects may include frequent headaches, blurred vision, or total vision loss. This occurs gradually over time and symptoms may not be evident in children. Kidney issues may arise such as
deposition of protein in the urine and nephritis. Proteinuria is usually the first sign of kidney involvement. It can reveal itself either rapidly or years after having asymptomatic deposition of protein in the urine,
kidney failure occurs in around 15% of NPS patients (in form of end-stage failure).
Irritable bowel syndrome and other gastrointestinal involvement, decreased sensation of pain and temperature in the hands and feet, e.g.
Raynaud syndrome and other vascular disorders,
attention deficit hyperactivity disorder (ADHD),
depression and thin tooth enamel are associated with NPS, but the exact nature of these relationships remains not fully explained.
General appearance (general phenotype) — it is possible and frequent to have lean body type (difficulty gaining weight even with a healthy and nutritious diet) and underdeveloped muscle mass, particularly in the limbs. It is most noticeable in young people with nail-patella syndrome, but not exclusively. Absence or underdevelopment of various muscles (e.g.
triceps, leading to thin structure of arms) and a high forehead — also may be present. However, low body weight sometimes can change (grow) with age, for example in women going through menopause, under the influence of other changes in metabolism, various medications and other factors. Eventual possible weight gain — later in life — does not necessarily have to be associated with an increase in muscle mass. Nail–patella syndrome may cause diverse and not always uniform symptoms in individual patients — it is associated with high phenotypic variability, even in the same family. In milder cases, some patients may only experience part of symptoms of this syndrome. Some potential symptoms (such as e.g. possible kidney damage or mentioned glaucoma) may appear and become more apparent with age and/or under the influence of additional aggravating factors. Other, than mentioned above, possible symptoms of NPS are also described in specialized sources, because the mutated gene can affect the entire body. ==Genetics==