Affected hairs develop stone-like black nodules affixed to the hair shaft that cause weakness of the hair. Infected hairs treated with potassium hydroxide fluoresce under ultraviolet light despite that the fungus itself does not normally fluoresce. Fluorescence of the piedra indicates secondary contamination by bacteria. Identification is easily achieved by microscopic examination of the hair nodules, and can be confirmed by sequence analysis of the nuclear ribosomal internal transcribed spacer region. Pathology
Piedraia hortae causes the formation of nodules on the hair shaft, a clinical superficial disease commonly known as black piedra. Black piedra is usually seen in tropical regions and it usually targets humans  of all ages and targets the scalp, moustache and occasionally pubic hair. The source of the infection is usually in soils, poor hygiene, long hair, cultural use of veils and the application of plant oils to wet hair favours the growth of the infection. Black piedra is a superficial fungal infection, which means that it is restricted to the stratum corneum and causes no inflammation. The infection of the hair shaft results in the formation of nodules on the scalp, moustache and pubic hair. The nodules are hard and gritty, which produce a metallic sound when the hair is combed. The nodules colonize the hair shaft, which causes progressive weakness of the hair and leads to breakage of the hair in severe cases, which can lead to hair loss and baldness. The fungus also has the potential to destroy the cuticular layers of the hair and move into the cortex.
Nail–patella syndrome  is a genetic disorder that results in small, poorly developed nails and kneecaps, but can also affect many other areas of the body, such as the elbows, chest, and hips. The name "nail–patella" can be very misleading because the syndrome often affects many other areas of the body, including even the production of certain proteins. : 666   Those affected by NPS may have one or more affected areas of the body, and its severity varies depending on the individual. It is also referred to as iliac horn syndrome, hereditary onychoosteodysplasia (HOOD syndrome), Fong disease or Turner–Kieser syndrome.Diagnosis of NPS can be made at birth but is common for it to remain undiagnosed for several generations. While there is no cure available for NPS, treatment is available and recommended. Signs and symptoms
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 90% 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 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 90% of patients. General hyperextension of the joints can be present.