Medical genetics in Israel

Ethnicity and prognosis in acute myeloid leukemia

Ethnicity has been described as a prognostic factor in breast cancer and in childhood acute lymphocytic leukemia but not in adult acute myeloid leukemia (AML). We reviewed the records of 225 consecutive AML patients who were diagnosed and treated between 1983 and 1995. Data were collected concerning demographic factors, presenting clinical features, and treatment protocols. We categorized ethnicity as follows: European Jews, non-European Jews, and Arabs. We assessed the role of ethnicity controlling for other known prognostic factors on treatment outcome and survival in this population. Older age, high leukocyte count at diagnosis, and high-risk chromosomal aberrations were significantly associated with overall survival in univariate analysis. In multivariate analysis high leukocyte count and high-risk chromosomal aberrations exerted an independent negative effect on survival. European origin was associated with longer event-free survival in univariate analysis (P = 0.024) and longer overall (P < 0.01) and event-free (P < 0.01) survival but not with a higher remission rate in multivariate analysis. For AML patients who achieved remission after induction chemotherapy and survived its complications, European origin is an independent favorable prognostic factor for long-term remission and survival in Israel. These findings may reflect better socioeconomic status, social support, increased compliance with treatment protocols, or better psychological coping mechanisms with malignancy.

Ethnic differences in the frequency of the C677T mutation in the methylenetetrahydrofolate reductase (MTHFR) gene in healthy Israeli populations

Hyperhomocysteinemia is an independent risk factor for arteriosclerotic vascular disease. It can result from deficiencies of co-factors required for homocysteine metabolism and/or from genetic disorders of its metabolism. The association between the C677T mutation in the methylenetetrahydrofolate reductase (MTHFR) gene and vascular disease is controversial, and may be affected by ethnic origin. A unique feature of the Israeli population is its ethnic diversity. The aim of this study was to study the frequency of the C677T MTHFR mutation in healthy Israeli ethnic groups. The frequency of the mutation was determined in 897 young healthy Jewish and Muslim Arab Israelis of eight different ethnic groups. Marked ethnic differences in the frequency of mutant homozygotes were found, ranging from 2% in Yemenite Jews, 4% in Sephardic Jews, 9% in Oriental Jews, 10% in Muslim Arabs, 16% in North African Jews, and 19% in Ashkenazi Jews. The frequency of mutant homozygotes was significantly higher in Ashkenazi Jews compared to Yemenites Oriental Jews, Sephardic Jews, and Muslim Arabs (chi2 = 12.35p < 0.001, chi2 = 8.17p = 0.004, chi2 = 6.04p = 0.01, chi2 = 6.54 p = 0.01, respectively). Our findings demonstrate the need for matching ethnic background in patients and controls when studying the association between the C677T MTHFR mutation and any disease.

Pre-marital genetic counselling to consanguineous couples: attitudes, beliefs and decisions among counselled, noncounselled and unrelated couples in Israel

Semi-structured interviews were conducted with 65 Israeli subjects who received genetic counselling while considering marriage to a close relative, 40 subjects married to a close relative who did not receive pre-marital genetic counselling, and 125 controls married to a nonrelative and never having considered marrying a relative. It was found that 72% of the consanguineous couples who received pre-marital genetic counselling proceeded with their plans and married their relative; 86% of them reported that the counselling influenced their final decision to some degree. Counsellees' appraisals of genetic counselling revealed unfulfilled expectations to obtain more definitive answers, and mixed reactions to the nondirective approach applied by the counsellors. Comparisons between consanguineous and control couples revealed different views about consanguinity in general, and genetic risks in particular. Consanguineous couples, unlike controls, perceived consanguinity as an ordinary form of marriage, and had more favorable attitudes towards it. Compared to the noncounselled consanguineous group, consanguineous couples who received pre-marital genetic counselling had fewer children, estimated their genetic risk as lower but its subjective significance as higher, and perceived genetic disorders as more severe. The implications of these results are discussed from both theoretical and practical standpoints.