Author(s) : Rudolf HAPPLE , Department of Dermatology, Philipp University of Marburg, Deutschhausstraße 9, D-35033 Marburg, Germany .
Summary : The genetic basis of congenital triangular alopecia (CTA) is so far not clear. The following arguments are presented in favor of the notion that this may be a paradominant trait. CTA usually occurs sporadically but may exceptionally affect several members of a family. The lesion is usually unilateral but bilateral involvement may likewise occur. CTA has been reported in association with phacomatosis pigmentovascularis, providing evidence that it may originate from loss of heterozygosity. Heterozygous individuals would be phenotypically normal. The trait would be expressed only when postzygotic loss of the corresponding wildtype allele occurred in a early developmental stage. Future molecular research may show whether the concept of paradominant inheritance holds true.
Keywords : congenital triangular alopecia, temporal triangular alopecia, loss of heterozygosity, mosaicism, paradominant inheritance
Pictures
Figure 1. Congenital triangular alopecia in a
2-year-old girl.
Figure 2. A photograph provided by the family
shows that the lesion was present at birth.
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