Heredity of idiopathic haemochromatosis: a study of 106 families.

More than 80% of the first degree relatives of 106 patients with iron overload - 97 with idiopathic haemochromatosis (I.H.) and nine with haemosiderosis secondary to alcohol induced liver disease (A.H. - were examined. Physical examination and measurement of plasma iron level and UIBC were done in all subjects; relatives who presented with some anomaly were submitted to a desferrioxamine test and, if the latter showed a high urinary iron output, to a liver biopsy. While absent in relatives of A.H. patients, iron overload was present in 78 out of 499 relatives of I.H. patients: 29 major and 49 minor forms. The major forms involved the sibships almost exclusively. The genetic analysis showed much evidence in favour of a recessive or rather intermediate form of inheritance, with heterozygous developing minor forms. However, other modes of transmission, especially polygenic (probably oligogenic), cannot be totally excluded. Data from recent studies showing a strong correlation between I.H. and certain HLA antigens do not conflict with the above conclusions.