Leukonychia
Leukonychia (or leuconychia) is a medical term for white discoloration appearing on nails. It is derived from the Greek words leuko 'white' and onyx 'nail'. The most common cause is injury to the base of the nail (the matrix) where the nail is formed. This condition consists of a whitening of the entire nail and mostly likely occurs on all nails. Whitening of one, and only one, entire nail is not recognized as a symptom of Leukonychia totalis but as a likely result of mechanical trauma. Leukonychia totalis may be a clinical sign of hypoalbuminaemia (low albumin), which can be seen in nephrotic syndrome (a form of kidney failure), liver failure, protein malabsorption and protein-losing enteropathies. A genetic condition or a side effect from taking sulphonamides (a family of antibiotics) can also cause this appearance. By 2011, only 6 cases of non-hereditary Leukonychia totalis were published. In familial cases of leukonychia totalis, this condition is caused by mutations in the PLCD1 gene, in chromosome 3p22.2, this mutation shows an autosomal dominant pattern of inheritance, but in some cases, this condition may be autosomal recessive. This condition consists of a whitening of parts of the nail plate in the form of small white dots. There are three different variations of partial leukonychia; punctate, transverse and longitudinal leukonychia. Some of the more serious variations of leukonychia partialis may lead to leukonychia totalis. Mees' lines Leukonychia striata, transverse leukonychia, or Mees' lines are a whitening or discoloration of the nail in bands or "stria" that run parallel to the lunula (nail base). This is commonly caused by physical injury or disruption of the nail matrix. Common examples include excessive biting or tapping of the nails, trauma or injury from accidents involving doors or windows, and extensive use of manicure. It may also occur in great toenails as a result of trauma from footwear. Alternatively, the condition can be caused by heavy metal poisoning, most commonly by lead.