RECURRENCE OF NEONATAL HEMOCHROMATOSIS IN HALF SIBS BORN OF UNAFFECTED MOTHERS

We report two families in which neonatal haemochromatosis was observed in half sibs. In the first family, two successive girls were born of different fathers. In the second family, an affected brother and siste r were followed by an affected half brother born after donor inseminat ion. These observations, as well as a previous abstract describing two affected half sisters, revive the debate over the inheritance of neon atal haemochromatosis. Incomplete penetrance or gonadal mosaicism for a dominant disorder, a maternal ''environmental factor'', or mitochond rial defect may be more suitable explanations than autosomal recessive inheritance in this condition. Alternative modes of fertilisation, su ch as donor insemination or in vitro fertilisation with donor eggs, sh ould be considered with caution.