A genetic analysis of 96 pedigrees has confirmed our previously published report and demonstrated an autosomal recessive mode of inheritance for idiopathic haemochromatosis. Three generations have been analyzed in each family: the sibship of the patient; the parents of the patient; the offspring of the patient. All the data are consistent with a recessive autosomal transmission: (1) An increased rate of consanguineous matings was found among the parents of the patients. (2) Not a single patient having the disease (latent or manifat) was found among either the parents or the children of the probands. (3) Three distinct levels of iron stores ‐ normal, slightly increased and heavily overloaded ‐ have been statistically separated in the haemochroma‐totic families. (4) The result of a segregation analysis has shown a percentage of parsom with heavy iron overloads per sibship corresponding to that expected for a recessive autosomal transmission, taking into account a penetrance of 0.20 in the female (the estimate used in this study).
