Israel Medical Association Journal

Background: Genetic screening tests for cystic fibrosis (CF), fragile X (FRAX) and spinal muscular atrophy (SMA) have been offered to the entire Arab population of Israel in the last few years. Since 2008, screening for CF is provided free of charge, but for FRAX and SMA the screening is privately funded with partial coverage by complementary health insurance programs.

Objectives: To assess the compliance of Arab couples for genetic screening tests, and the factors that affect their decisions.

Methods: We analyzed compliance for genetic screening tests at the Emek Medical Center Genetic Institute, and in outreach clinics in four Arab villages. We enquired about the reasons individuals gave for deciding not to undergo testing. We also assessed the compliance of these individuals for the triple test (a screening test for Down syndrome).

Results: Of the 167 individuals included in our study, 24 (14%) decided not to be tested at all. Of the 143 (86%) who decided to be tested, 109 were tested for CF only (65%) and 34 (20%) for SMA and FRAX (as well as CF). The compliance rate for the triple test was 87%. Technical reasons, mainly financial issues, were the most significant factor for not undergoing all three tests.

Conclusions: The compliance of the Arab community for genetic testing for SMA and FRAX is extremely low. We believe that this low utilization of screening is due to economic reasons, especially when a complementary health plan has not been acquired, and largely reflects the perception that these tests are less important since they are privately funded.
 

Background: Genetic hemochromatosis leads to iron overload in many tissues and may lead to liver cirrhosis and hepatocellular carcinoma. Early diagnosis and therapy are crucial. Since 80–100% of hemochromatosis patients of European origin are homozygous for a cysteine to tyrosine exchange in the HFE gene at codon 282, genetic screening might be useful. Representative population studies are needed to evaluate the phenotype of people heterozygous and homozygous for the C282Y mutation.

Objective: To determine the correlation between parameters of iron metabolism and the hemochromatosis genotype in a large population-based study.

Methods: A representative population-based survey, the Diabetomobil study, analyzed 5,083 German probands. Serum transferrin saturation and ferritin levels were determined, and the C282Y mutation of the HFE gene was analyzed by restriction fragment length polymorphism- polymerase chain reaction analysis.

Results: Nine of 373 probands with a transferrin saturation > 55% (2.4%) and none of 264 randomly selected probands with a transferrin saturation £ 55% (0%) were homozygous for the C282Y mutation. Three of the nine homozygous probands had ferritin values less than 250 µg/L. The frequency of the heterozygous genotype was 8.8%, and the percentage of heterozygous probands increased with increasing levels of transferrin saturation.

Conclusion:We propose a population screening strategy with an initial transferrin saturation test, followed by genotyping for the C282Y mutation if the transferrin saturation is above 55%, regardless of the ferritin level. Heterozygous individuals with higher transferrin saturation values may be protected against iron loss but may also be more susceptible for certain liver diseases, depending on the simultaneous prevalence of other diseases.
 

Background: The Bloom syndrome gene, BLM, was mapped to 15q26.1 and its product was found to encode a RecQ DNA helicase. The Fanconi anemia complementation group C gene was mapped to chromosome 9q22.3, but its product function is not sufficiently clear. Both are recessive disorders associated with an elevated predisposition to cancer due to genomic instability. A single predominant mutation of each disorder was reported in Ashkenazi Jews: 2281delATCTGAinsTAGATTC for Bloom syndrome (BLM-ASH) and IVS4+4A®T for Fanconi anemia complementation group C.

Objectives: To provide additional verification of the mutation rate of BLM and FACC[1] in unselected Ashkenazi and non-Ashkenazi populations analyzed at the Sheba Medical Center, and to trace the origin of each mutation.

Methods: We used polymerase chain reaction to identify mutations of the relevant genomic fragments, restriction analysis and gel electrophoresis. We then applied the Pronto^TM kit to verify the results in 244 samples and there was an excellent match.

Results: A heterozygote frequency of 1:111 for BLM-ASH and 1:92 for FACC was detected in more than 4,000 participants, none of whom reported a family history of the disorders. The Pronto^TM kit confirmed all heterozygotes. Neither of the mutations was detected in 950 anonymous non-Ashkenazi Jews. The distribution pattern of parental origin differed significantly between the two carrier groups, as well as between each one and the general population.

Conclusions: These findings as well as the absence of the mutations in non-Ashkenazi Jews suggest that: a) the mutations originated in the Israelite population that was exiled from Palestine by the Roman Empire in 70 AD and settled in Europe (Ashkenazi), in contrast to those who remained; and b) the difference in origin distribution of the BS[2] and FACC mutations can be explained by either a secondary migration of a subgroup with a subsequent genetic drift, or a separate geographic region of introduction for each mutation.

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[1] FACC = Fanconi anemia complementation group C