Familial partial lipodystrophy: two types of an X linked dominant syndrome, lethal in the hemizygous state.

Familial lipodystrophy (referred to in publications as the Köbberling-Dunnigan syndrome) comprises at least two clinical phenotypes which are consistent within each pedigree. In type 1 familial lipodystrophy, loss of subcutaneous fat is confined to the limbs, sparing the face and trunk. In type 2 familial lipodystrophy, the trunk is also affected with the exception of the vulva, giving an appearance of labial hypertrophy. Diabetes mellitus, hyperlipoproteinaemia, and acanthosis nigricans are present to a variable degree in some but not all patients with familial lipodystrophy, and the abnormal distribution of subcutaneous fat is the essential hallmark of the syndrome. In addition to a survey of published reports, new cases with the syndrome are described. Both types of partial lipodystrophy, occurring either as familial disease or as sporadic cases, have only been observed in female patients. Study of the pedigrees of five families with familial lipodystrophy (two Scottish and three German) suggests an X linked dominant mode of transmission, lethal in the hemizygous (XY) state. The two clinical phenotypes with their variably expressive metabolic abnormalities are consistent either with different mutants of the same allele or with two genes on adjacent loci. Other clinical phenotypes of familial lipodystrophy may exist due to further mutations of the same allele or of genes on adjacent loci. The nature of the disorder in patients with familial lipodystrophy usually escapes recognition for many years and the syndrome is almost certainly much commoner than the few families described to date suggest.