Description, Causes and Risk Factors:
Anonychia and hyponychia are rare anomalies. Congenital anonychia is the total absence of the nail in one or more fingers or toes. In hyponychia, there are some remnants of the nail present. These conditions are often accompanied by brachydactyly, which literally means "shortness of the fingers and toes (digits)." or even the complete absence of terminal phalanges.
Isolated cases of anonychia combined with facial dysmorphology, with deformation of the nose in particular, have been described in genetic literature.
Total anonychia congenita is a very rare disorder in which all the finger nails and the toenails are absent without significant bone anomalies. This condition is reported to have an autosomal dominant inheritance pattern. There are a variety of syndromes or conditions associated with anonychia congenita.
Most cases of anonychia occur as part of syndromes, e.g., in association with hypoplasia or absence of distal phalanges, e.g., Cooks syndrome, brachydactyly type B, ectrodactyly. Most of these associations are transmitted in an autosomal dominant manner
The mode of inheritance of most of these disorders has not yet been established with certainty. In a minority of individuals, there are striking and bizarre defects of the digits, sometimes restricted to one hand or foot. The defects usually take the form of omission of one or more digits. When the nails are absent, the nail bed is also missing.
Acquired anonychia result from total or partial destruction of the nail matrix due to in?ammatory disorders or trauma. Among in?ammatory disorders the most common cause is nail lichen planus, especially in its more severe form described as idiopathic atrophy of the nails. This condition develops very rapidly, with or without pterygium formation. Psoriasiform acral dermatitis (PAD), a rare condition that affects children, causes a typical shortening of the nail without underlying bone abnormalities. Nail lesions are associated with erythematous desquamative lesions of the ?ngertips.
Risk factors may include:
Congenital ectodermal defect.
Abstract: In a large German nonconsanguineous family with four affected and five unaffected siblings with isolated total congenital anonychia, we performed genomewide mapping and showed linkage to 20p13. Analysis of the RSPO4 gene within this interval revealed a frameshift and a nonconservative missense mutation in exon 2 affecting the highly conserved first furin-like cysteine-rich domain. Both mutations were not present among controls and were shown to segregate with the disease phenotype. RSPO4 is a member of the recently described R-spondin family of secreted proteins that play a major role in activating the Wnt/?-catenin signaling pathway. Wnt signaling is evolutionarily conserved and plays a pivotal role in embryonic development, growth regulation of multiple tissues, and cancer development. Our findings add to the increasing body of evidence indicating that mesenchymal-epithelial interactions are crucial in nail development and put anonychia on the growing list of congenital malformation syndromes caused by Wnt-signaling-pathway defects. To the best of our knowledge, this is the first gene known to be responsible for an isolated, nonsyndromic nail disorder.
Anonychia is a feature of junctional and dermolytic epidermolysis bullosa, where it is a sequela of bullae formation. It is usually associated with cutaneous blisters or erosions and periungual and subungual granulomatous tissue.
Other possible signs may include:
The diagnosis may include examination of a shape, contour, color, glossiness, translucency, consistency, deformity and structure. The later should include a study of the nail folds (both the posterior and lateral), the nail bed, the plate consisting of the root, the lunula and the body proper.
The non-surgical options may include ?nger prosthetics with arti?cial nails. This option is generally found uncomfortable due to the reduction of ?ngertip sensation with the prosthetics in place. Surgical options may include toe-to-?nger nail matrix grafting.
NOTE: The above information is educational purpose. The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition.
Reference and Source are from:
DISCLAIMER: This information should not substitute for seeking responsible, professional medical care.
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