Hereditary distal onycholysis is an autosomal dominant nail disorder characterized by a decreased rate of growth of the nail, scleronychia, and a straight or concave proximal edge of detachment. Clinical features may include palmoplantar hyperhydrosis and marked sensitivity ... Hereditary distal onycholysis is an autosomal dominant nail disorder characterized by a decreased rate of growth of the nail, scleronychia, and a straight or concave proximal edge of detachment. Clinical features may include palmoplantar hyperhydrosis and marked sensitivity of the fingers to cold (summary by Bazex et al., 1990). Hereditary distal onycholysis is referred to here as nonsyndromic congenital nail disorder-5 (NDNC5). For a list of other nonsyndromic congenital nail disorders and a discussion of genetic heterogeneity, see NDNC1 (161050).
Schulze (1966) described a mother and 2 children with onycholysis of the distal part of the fingernails, which were thickened. The disease was thought to have occurred in 5 generations. Bazex et al. (1990) stated that all fingernails ... Schulze (1966) described a mother and 2 children with onycholysis of the distal part of the fingernails, which were thickened. The disease was thought to have occurred in 5 generations. Bazex et al. (1990) stated that all fingernails and toenails were involved in the family described by Schulze (1966), and that the partial onycholysis was associated with a slowing of nail growth, thick and hard nails (scleronychia) as well as increased transverse curvature in some nails, and absent lunulae. Affected individuals complained of extreme sensitivity to cold and pressure with paresthesia but no Raynaud phenomenon (179600). Palmoplantar hyperhidrosis of variable severity was found in all patients, and painful fissures occurred on the soles. Examination of skin, teeth, hair, and mucosa was normal except for thinning of eyebrows in 1 patient with lanugo-like hair. Hundeiker (1969) described a family in which a mother and daughter and the mother's father had distal onycholysis of the nails of the fifth toes. The disorder developed in the second year of life, beginning with longitudinal furrows on the middle and lateral thirds of the nail followed by splitting, which began at the free edge and progressed proximally to the nail fold. The nail splitting was present bilaterally in the mother and daughter and unilaterally in the mother's father. Burg (1975) reported a pedigree in which the proband had involvement of all fingernails and toenails, with changes occurring gradually over 10 years. The fingernails were smooth and thickened with an increased transverse curvature, and were slightly elevated and separated from the nail bed in the distal half. The nail color distally was a waxy dull yellow, whereas proximally the color was normal, translucent and pale pink. Similar changes were present in the toenails, associated with more prominent onychodystrophy and subungual hyperkeratosis. Nail growth rate was said to be normal. No changes were observed in the hair or mucous membranes or the remainder of the skin. The proband's father, paternal aunt, paternal grandmother, and father's cousin had similar changes in their nails. Bazex et al. (1990) described a 51-year-old woman who first noted distal onycholysis of the fingernails at age 25 years, with involvement of the toenails at age 40. The shape of the nails was unchanged except on the third fingers, which had increased transverse curvature. There was swelling of the proximal nailfold on the right index finger and an accentuation of longitudinal ridging on the right third finger. Lunulae were absent except on the thumbs. There was a slight decrease in brightness of the attached portions of the nail plate, with color varying from pale gray to pink. The proximal border of onycholysis was straight or concave and the nail plates were opaque, yellowish-white, brownish, or sometimes blackish on the lateral edges. The degree of separation varied from nail to nail. Nail growth was slower than normal, and the nails were thick and hard to cut. The onycholysis was less marked on the feet and mainly affected the great toes. The changes were intermittent with frequent relapses. Examination of the hands and feet showed palmoplantar hyperhidrosis. The patient reported marked sensitivity to cold with subungual paresthesia, but there was no Raynaud phenomenon. Repeated mucologic and bacteriologic examinations were negative. Histologic study of a nail fragment showed normal structure of the nail plate, with parakeratosis in the hyponychium. X-rays of the hands and feet were normal; scalp, mucous membranes, eyes, ears, and hair were normal, and microscopic examination of the hair was normal. The proband's mother, maternal grandmother, and the mother's cousin had similar nail changes, but her mother did not have hyperhidrosis.