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

What is Dysmorphology?

Dysmorphology is the aspect of clinical genetics concerned with syndrome diagnosis in children who have a combination of congenital malformations and unusual facial features, often with delayed motor and cognitive development. There are at least 3500 distinct syndromes at present,[1] although many new ones are described each year. Some, such as neurofibromatosis type 1,[2] tuberous sclerosis[2] and multiple endocrine adenomatosis type 2B,[3] are well characterized and known to dermatologists, but others are rare and described only occasionally in the literature. Syndrome recognition and diagnosis is of clinical importance for several reasons. First, it influences patient management because awareness of the pattern of anomalies associated with a particular syndrome highlights the investigations that need to be undertaken. For example, Beckwith-Weidemann syndrome (naevus flammeus, macrosomia, neonatal hypoglycaemia, umbilical hernia) is associated with an increased risk of Wilms tumour.[4] Children with this condition, which can usually be diagnosed in the neonatal period, should undergo regular screening for early detection of the renal tumour, and various protocols have been proposed.[5] Second, syndrome diagnosis provides information about the long-term prognosis and may help to identify options for treatment: for example, bone marrow transplantation or enzyme therapy can now be offered for some inborn errors of metabolism (e.g. in Fabry disease[6]). Third, the diagnosis determines what genetic advice can be given, including an estimation of genetic risks and possible means of prenatal diagnosis.

Beyond these clinical aspects, dysmorphology has contributed much to current understanding of the genetic basis of human development. Studies of syndromes with very specific features have led to the isolation of the causative genes and discovery of the mechanisms by which those genes play a part in normal embryogenesis.[7] For example, the gene for X-linked hypohidrotic ectodermal dysplasia was initially mapped in families with affected boys.[8] Subsequent studies led to identification of the gene encoding a novel transmembrane protein expressed in keratinocytes[9] and demonstrated that the protein associates with the cell membrane and induces morphological changes in epithelial cell lines.[10] Thus clinical studies of one condition can provide insights into broader aspects of skin development.

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