Multiple neurofibromatosis is known to be a genetic disease with the autosomal dominant inheritance pattern. In clinical practice, however, we can hardly ever find a case in which the autosomal dominant inheritance is demonstrable, because sporadic mutation is believed to cause about 50% of the observed multiple neurofibrom-
atosis cases, and because such patients show reduced fertility.
The authors observed a family case in which the typical autosomal dominant inheritance could be demonstrated. Among 17 consanguinities of the 3 generations studied, 12 had developed multiple neurofibromatosis.
The presumed reason for the high incidence of the disease in the family studied is 2 fold:
1) The autosomal dominant gene responsible for the disease is highly penetrable.
2) The mutant gene responsible for the disease, for some unexplained reason, was transmitted from patient No. 1 to all of her offsprings, instead of to only half of her offsprings, as would be expected.
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