The mutation has high penetrance and variable expression, which means that nearly all people with the gene show signs of the condition, but these signs can range from very mild to very obvious. Diagnosis
Epidemiology
The actual incidence of this disease is not known, but only 243 cases have been reported in the scientific literature, suggesting an incidence of on the order of one affected person in ten million people. References


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They are also seen in patients with end-stage kidney disease on hemodialysis, Hodgkins disease, pellagra, and sickle cell anaemia.The lines remain visible as long as protein intake is inadequate or synthesis is impaired, and they should disappear upon return to normal function.In extreme conditions, Muehrckes lines may also arise from physical changes in peripheral circulation: one case study reported appearance of the lines in a healthy subject following ascent to 8,848 meters (29,029 ft) on Mount Everest. History
Muehrckes lines were described by American physician Robert C. Muehrcke (1921–2003) in 1956. In a study published in BMJ, he examined patients with known chronic hypoalbuminemia and healthy volunteers, finding that the appearance of multiple transverse white lines was a highly specific marker for low serum albumin (no subject with the sign had SA over 2.2 g/dL), was associated with severity of the underlying condition, and disappeared upon successful treatment (corticosteroids in nephrotic syndrome) or direct infusion of HSA. See also
Mees lines – a similar appearance, except the lines are in the nail and move as the nail grows
Half and half nails
Terrys nails
List of cutaneous conditions

References
Bibliography
Fawcett, Robert S.; Sean Linford; Daniel L. Stulberg (March 15, 2004). "Nail Abnormalities: Clues to Systemic Disease". American Family Physician. 69 (6): 1417–24. PMID 15053406. James, William; Berger, Timothy; Elston, Dirk (2005). Andrews Diseases of the Skin: Clinical Dermatology. (10th ed.). Saunders. ISBN 0-7216-2921-0. Muehrcke Lines of the Fingernails at eMedicine
Muehrckes Lines of the Fingernails on WebMD