Nonsyndromic congenital nail disorder 1

Many types of nonsyndromic congenital nail disorders (NDNC) have been described. Twenty-nail dystrophy (TND), also known as trachyonychia (from the Greek for 'rough nails'), is an autosomal dominant nail dystrophy characterized by excessive longitudinal striations and numerous superficial pits on the nails, which have a distinctive rough sandpaper-like appearance. Occasionally some nails are spared. The slowly progressive condition is usually apparent at birth and may be self-limiting, with spontaneous resolution in some patients (summary by Sehgal, 2007). TND is referred to here as nonsyndromic congenital nail disorder-1 (NDNC1). Genetic Heterogeneity of Nonsyndromic Congenital Nail Disorders Other nonsyndromic congenital nail disorders include koilonychia (NDNC2; 149300); leukonychia (NDNC3; 151600) caused by mutation in the PLCD1 gene (602142) on chromosome 3p22; anonychia/hyponychia (NDNC4; 206800) caused by mutation in the RSPO4 gene (610673) on chromosome 20p13; partial onycholysis with scleronychia (NDNC5; 164800); anonychia of thumbs with onychodystrophy of other nails (NDNC6; 107000); onychodystrophy mapping to chromosome 17p13 (NDNC7; 605779); toenail dystrophy (NDNC8; 607523) caused by mutation in the COL7A1 gene (120120) on chromosome 3p21; onychodystrophy mapping to chromosome 17q25.1-q25.3 (NDNC9; 614149). [from OMIM]