Summary. Three cases of cerebral gigantism, two sibs and their double first cousin, are describedina largeinbred family from Israel. Two of the three were observed and diagnosed at birth and two were followed for two years. They all presented the signs and symptoms considered typical ofthis syndrome, as well as some ofthe less frequent findings. Generalized oedema and flexion contractures of the feet were observed in two of the three at birth. This has not hitherto been reported in cases of cerebral gigantism, of whom only a few have been observed and diagnosed at birth. Autosomal recessive inheritance is clearly implied in this family.

HLA gene frequencies in 11 Israeli populations and nine other relevant populations were used to calculate genetic distances in a quantitative assessment of their similarities and differences. The shortest distance found is between Polish and Rumanian Jews, while the largest is between Russian Jews and Black Africans. Estimates of "average" distances within major population groups suggest that the Ashkenazi Jews (Poles, Russians, Rumanians and Germans) are a more homogeneous population than East European non-Jews or than Middle-Eastern populations (Arabs, Armenians, Lebanese and Turks). A cline of distances between Ashkenazi Jews and other Jewish communities parallels their geographic distribution; however, the relatively large distance between the two North African communities (Libyans and Moroccans) demonstrates that geographic proximity is not necessarily correlated with genetic similarity. The Jewish populations, especially the Ashkenazi, show a clear divergence from their neighboring non-Jewish populations, among whom they have lived for many centuries. There are indications in the HLA data of a common origin for the diverse Jewish populations.

Haptoglobin types were determined on 211 patients with leukemia of the four most common types: acute lymphatic (ALL), chronic lymphatic (CLL), acute myeloid (AML), and chronic myeloid leukemia (CML). Frequency distributions of the three common Hp types in patients differed significantly from the control population. A significant increase in the relative incidence of Hp 1-1 was observed in patients with ALL, AML, and CML, but not with CLL. A similar trend was consistent in the data from previously published studies for the same three types of leukemia but not for CLL. Our results and the analysis of data from previous studies, suggest an association of Hp type with some leukemias, which is expressed in a consistent elevation of Hp 1-1 type among leukemia patients with ALL, AML, and CML.

Gc subtypes were determined by immunofixation isoelectric focusing. In a family study involving 93 families with a total of 176 children, a three-allele model with six genotypes was confirmed. The distribution of Gc subtypes was studied in three populations from Europe and in a sample of Druzes from Northern Israel. Three new variant Gc types were observed.

Analysis of data from 80 families and 369 unrelated individuals confirms the hypothesis that human red cell acid phosphatase phenotypes are determined by three codominant alleles at a single autosomal locus. Further confirmation is afforded by the finding of the predicted sixth phenotype.