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Microcephaly is a heterogeneous disorder with genetic and environmental causes. However, there is little information on what proportion of cases are caused by inherited susceptibility, or the mode of inheritance in familial cases. To address these questions, we have performed classical and complex segregation analyses for microcephaly on 2 sets of family data collected from genetic counseling clinics in Vancouver and Jerusalem. These samples consisted of 143 affected individuals in 127 families ascertained from Vancouver, and 101 affected individuals in 59 families ascertained from Jerusalem. The results of the segregation analyses for the Vancouver sample indicated that approximately half of all microcephaly cases were due to highly penetrant recessive mutant alleles, with the remainder being sporadic. Although a recessive model allowing for the occurrence of sporadic cases fit the data from Vancouver best, a dominant model could not be statistically rejected. The classical segregation analysis on the Jerusalem sample suggested that both a dominant model with 29% of the cases being sporadic and a purely recessive model provided adequate fit to the data. Although the complex segregation analysis of this sample indicated that a dominant model provided a more parsimonious explanation for the observed familial variation, a recessive model was only marginally rejected. It should be noted that in the Jerusalem sample, families tended to be ascertained in the genetic counseling clinic only after the birth of a second affected child. This could be a potential bias which could inflate the segregation ratio, thus giving the impression of dominant inheritance. Our analyses, while confirming the complex nature of the cause of microcephaly, indicate that it may be necessary to await the results of genetic linkage analysis before a definitive mode of inheritance can be determined.

Fourteen families in which more than one child was diagnosed with hydrocephalus of prenatal onset were seen in our genetic counseling clinic. In 7 families only males were affected: in 2 X-linked hydrocephalus was diagnosed while X-linked inheritance was suspected in 3 other families. These 5 families were of Jewish origin. In the 8 families of Arab origin, the parents of the affected children were consanguineous. In 6 of these families at least one female was affected and the hydrocephalus was most probably inherited as an autosomal recessive trait. This type of hydrocephalus of prenatal onset appears to be frequent among Palestinian Arabs.

Parents of children with cleft lip and/or palate (42 women and 35 men) participated in a study on intentions to use prenatal diagnosis of cleft by ultrasound in subsequent pregnancies. Based on the Health Belief Model (HBM) [Rosenstock, 1974], parents' cognitions on 4 factors were measured by questionnaires: "susceptibility" and "severity perceptions," "benefits" and "barriers" evaluations. Most parents perceived the defect as severe. Over-estimation of recurrence risks was predominant even among parents who had received genetic counseling. Results showed that most parents intend to utilize prenatal diagnosis but do not intend to abort an affected fetus. Subjects' reported reasons represented 3 thematic categories: cognitive (the need to know), emotional, and behavioral. Parents' intentions to diagnose and to terminate were related to the factors predicted by the HBM model. Regression analyses indicated that 38% of the variance in intentions to diagnose and 56% of the variance in intentions to terminate could be explained by the studied variables. The best predictor of both intentions was the perceived benefits of the diagnosis. Implications of these findings for genetic counseling are discussed.

Steroid 11 beta-hydroxylase deficiency is relatively frequent in Israel among North African Jews. Over a 39-year period, 38 affected individuals from 25 families were diagnosed. Nineteen families came from Morocco, and in another 2, one parent came from Morocco (80% of all parents). Demographic studies showed that most of their grandparents were born in the region of the Atlas Mountains. In Israel, the overall incidence of the disorder is estimated between 1 in 30,000 to 1 in 40,000 births, but in offspring of Moroccan Jews the ratio is 1 in 5,000 to 1 in 7,000, with an allele frequency of 1 in 70 to 1 in 84 and a carrier frequency of 1 in 35 to 1 in 42. The clinical expression is characterized by a wide range of variability in the signs of androgen and mineralocorticoid excess. Virilization in the female ranged from enlarged clitoris in the mildest forms, to markedly hypertrophied clitoris with penile urethra and fused labial-scrotal folds in the most severe forms. Hypertension causing vascular accidents and death was observed in both severe and mildly virilized patients, whereas masculinized females were sometimes normotensive. Based on historical evidence, the origin of the ancestors, and the onomastic analysis of the families surnames, we propose that the mutation of 11 beta-hydroxylase deficiency in Jews from Morocco may have originated in either the ancient Jewish settlers or the native Berber tribes who lived in the region of the Atlas Mountains in the southern region of Morocco before the destruction of the Second Temple by the Romans, in the year 70 C.E.

Deafness occurs in about 1 per thousand live births, and at least 50% of congenital deafness is hereditary. The aim of this study was to examine the number of loci for recessively inherited severe nerve deafness of early onset within the Israeli population and to compare the results to those obtained in other populations. The Jewish population in Israel originates from many countries and may be divided into Sephardi, Eastern and Ashkenazi Jews, and the matings will be intraethnic or interethnic. Data were obtained on 133 deaf couples who lived in the Tel Aviv area, through the files of the Helen Keller Center. Causes of deafness in the spouses were studied and data on their children were obtained. Among 111 couples who had recessive or possibly recessive deafness and had at least 1 child, there were 12 with only deaf children and 5 with both deaf and hearing children. The number of loci for recessive deafness in the whole group was estimated at 8-9. Intraethnic and interethnic matings gave an estimate of 6.7 and 22.0 loci, respectively, which indicates that within populations fewer loci exist with recessive mutations for deafness than between populations. It could be shown that the sharing of loci between spouses decreased with increasing geographical distance of their origin. The results provide data for genetic counseling in Israel for deaf couples who have no children or have one hearing or one deaf child.

In 3 families 4 patients were affected with the syndrome of brittle cornea, blue sclera, and hyperextensible joints (brittle cornea syndrome). From the review of 17 affected patients described previously and our cases, it appears that this rare autosomal recessive syndrome has variable expressivity. Two different groups of patients may be distinguished: one includes 5 families, all of Tunisian Jewish origin. All patients in this group also have red hair. In the second group, 9 families are from various ethnic origins; affected patients in this group have a normal distribution of hair color. A possible explanation for the existence of these 2 different group of patients is that the locus of the gene responsible for the syndrome is closely linked to the locus for a gene responsible for hair color with linkage disequilibrium in Tunisian Jews (Sepharadim).

Serum samples from 223 Jews from Cochin, India were tested for Gm(1,2,3,5,6,13,14,17,21,26) and for Inv(1). Certain samples were also tested for Gm(15) and Gm(16). The Cochin Jews are polymorphic for: 1) Gm3, a haplotype that does not lead to the formation of gamma 3, as was shown by tests of the serum of a homozygote, and 2) Gm1,17,21, a haplotype lacking Gm(26), which is ordinarily present in this haplotype. The Gm data indicate considerable admixture with southern Indians. There is no evidence for African admixture, such as has been found for all other Jewish populations studied thus far. The Inv data are similar to those for other Jewish populations.

We have investigated a family with one child affected with congenital adrenal hyperplasia (CAH) due to 21-hydroxylase deficiency. Prenatal determination of 17-alpha hydroxyprogesterone (17OHP) in amniotic fluid (AF) and HLA typing of amniotic fibroblasts from a pregnancy at risk showed that the fetus was not affected. A healthy cousin with HLA haplotypes identical to those of the proposita (only one being identical by descent) had a normal plasma level of 17OHP. The prenatal diagnosis of a fetus affected with 21-hydroxylase deficiency CAH may be established by the determination of 17OHP in AF. This is a relatively quick procedure that can be confirmed by the HLA genotype, and is mandatory in families with a parent homozygous for an HLA haplotype and in certain recombinant haplotypes in the fetus.