Diagnosis in Dysmorphology: Clues From the Skin

S.F. Smithson; R.M. Winter

Disclosures

The British Journal of Dermatology. 2004;151(5) 

In This Article

Genetic Basis of Syndromes

Many syndromes have a genetic basis and can be caused by chromosome rearrangements or by single gene defects following mendelian inheritance. There are numerous single genes associated with skin disorders, and a recent review in this Journal drew attention to clinical and molecular genetic heterogeneity and the complexities of genotype-phenotype relationships.[16] In assessing dysmorphic syndromes with skin signs, the clinician also needs to consider atypical genetic mechanisms such as mosaicism, uniparental disomy, imprinting and mitochondrial inheritance. In recent years there has been a rapid increase in the number and scope of genetic tests which provide more precise ways of confirming a syndrome diagnosis. Some syndromes with dysmorphic features and congenital malformations are not genetically determined, resulting instead from congenital infections (such as varicella which may cause skin scarring over dermatomes, limb hypoplasia, low birth weight, mild mental retardation, cataract and chorioretinitis[17]) or teratogens (for example, the abortifacient drug misoprostol is associated with extensive frontotemporal defects of the scalp and cranial bones[18]). Some congenital malformations, also referred to as developmental field defects, are unilateral and isolated to one anatomical region. Frequently they have no obvious cause but may be associated with maternal factors such as diabetes mellitus.[19] Many malformations that are apparently isolated, including cleft lip and palate and neural tube defects, may result from complex genetic and environmental interactions which are the subject of much research and debate.[20]

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