Alopecia: syndromes of genetic significance

Abstract

Except for common baldness, the loss of axillary and body hair in the aged (especially in postmenopausal women) and the absence of hair growth in the testicular feminization syndrome or other similar rare conditions, most cases of alopecia are not directly related to hormonal factors. Genetic factors are an important consideration the causation of many types of alopecia some of which are poorly understood. Among the disorders wherein hair loss is the only abnormality present, alopecia congenita universalis and the Marie Unna type of hereditary hypotrichosis are among the most important. Hair loss as part of a more generalized ectodermal dysplasia or complex congenital syndrome is not uncommon and may be inherited as an autosomal recessive, autosomal dominant, x linked recessive or x linked dominant disorder. There are also a number of types of alopecia associated with deformities of the hair shaft which are of variable severity and inheritance. Pattern alopecia in men and women is probably the same disorder, the inheritance of which has not been settled. A multifactorial type of causation is likely in alopecia areata. Much more needs to be learned about the causes of hair loss in the syndromes of alopecia. Suitable genetic studies should provide much information as well as improve our clinical acumen. Available methods for study of hair loss disorders should be carried out whenever possible, particularly the simple clinical ones that are applicable to office practice such as routine hair pluck examination and histopathologic examination of scalp biopsies. Additional insights into a number of medical disorders in which alopecia in either a major or a minor feature could be achieved by the direct application of currently available research techniques to the analysis of the affected hairs themselves.