Search

Approximately one in three Ashkenazi Jews are carriers for an autosomal recessive Jewish genetic disease (JGD). However, studies indicate that most Jews are uneducated on this topic and obstetricians do not routinely offer carrier screening to Jewish patients. Both the Reform and Conservative movements of Judaism call for JGD education to take place within the synagogue; however, little is known about the extent of this education occurring today. An online survey was created for Reform and Conservative rabbis to assess the types of JGD education taking place within the synagogue. Additionally, the survey included questions to assess JGD knowledge and possible factors that could predict counseling activity and knowledge level. Of the 94 participants, 91% had provided education about JGDs to congregants, with 98.8% providing this education during premarital counseling sessions. For most respondents, explaining recessive inheritance pattern and carrier screening was the extent of the discussion. Additionally, the majority of rabbis scored below 50% on the knowledge portion of the survey, with an average score of 1.9/4. There were no statistically significant differences between JGD education in Reform vs. Conservative synagogues, and there were no statistically significant predictors of knowledge score or JGD education frequency. In conclusion, while the number of rabbis discussing this topic is encouraging, discussion topics were found to be limited and their knowledge of JGDs was found to be poor.

Experiences from a pilot program bringing BRCA1/2 genetic screening to theUS Ashkenazi Jewish population

Population screening of three common BRCA1/BRCA2 mutations in Ashkenazi Jews (AJ) apparently fulfills screening criteria. We compared streamlined BRCA screening via self-referral with proactive recruitment in medical settings. Unaffected AJ, age ≥25 years without known familial mutations, were either self-referred or recruiter-enrolled. Before testing, participants received written information and self-reported family history (FH). After testing, both non-carriers with significant FH and carriers received in-person genetic counseling. Psychosocial questionnaires were self-administered 1 week and 6 months after enrollment. Of 1,771 participants, 58% were recruiter-enrolled and 42% were self-referred. Screening uptake was 67%. Recruited enrollees were older (mean age 54 vs. 48, P 90%). At 6 months, carriers had significantly increased distress and anxiety, greater knowledge, and similar satisfaction; 90% of participants would recommend general AJ BRCA screening. Streamlined BRCA screening results in high uptake, very high satisfaction, and no excess psychosocial harm. Proactive recruitment captured older women less selected for FH. Further research is necessary to target younger women and assess other populations. Genet Med advance online publication 08 December 2016

The knowledge, attitudes, and barriers to Jewish genetic diseases (JGDs) and screening and their relative importance in reproductive decision-making were assessed in a population-based sample of Ashkenazi Jewish young adults in Florida. These adults attended educational screening fairs hosted by The Victor Center for the Prevention of Jewish Genetic Diseases at the University of Miami. Parametric and nonparametric tests were used as appropriate to analyze data from a single group pretest/posttest design. Four hundred twelve individuals (mean age = 24.9; 54.7 % female, 45.3 % male) completed the questionnaires. Participants' level of knowledge increased from pre- to post-intervention (81.4 vs. 91.0 %; p

Aims: Advances in genomics may eventually lead to genetic susceptibility screening of the general population, regardless of a personal or familial history of the disease in question. Yet, little is known about clinicians' attitudes toward such programs. We explored attitudes of family practitioners, medical geneticists and genetic counselors toward genetic screening of the general Ashkenazi-Jewish population for the common founder mutations in BRCA1/2 and LRRK2 genes (which increase the risk of hereditary breast/ovarian cancers and Parkinson's disease, respectively). Methods: Participants (n = 204) completed a specially designed questionnaire, distributed by e-mail, regular mail or in-person. Results: Slightly more than half (52%) were in favor of BRCA screening, while the vast majority (86%) opposed to LRRK2 screening. About two-thirds (68%) of the respondents supported pre-test genetic counseling. Attitudes were largely independent of professional background and sociodemographic characteristics, though a correlation was found with personal interest in genetic self-testing for the above genes. Adverse psychological impact and discrimination in insurance and employment were the major concerns cited by respondents with regard to screening programs. Conclusion: Our findings suggest that the availability of measures for prevention and/or treatment is a major factor in the attitudes of healthcare providers toward population screening for late-onset conditions.

Tay-Sachs disease (TSD) carrier screening, initiated in the 1970s, has reduced the birth-rate of Ashkenazi Jews with TSD worldwide by 90%. Recently, several nationwide programs have been established that provide carrier screening for the updated panel of Jewish genetic diseases on college campuses and in Jewish community settings. The goals of this study were to determine the performance characteristics of clinical TSD testing in college- and community-based screening programs and to determine if molecular testing alone is adequate in those settings. Clinical data for TSD testing were retrospectively anonymized and subsequently analyzed for 1,036 individuals who participated in these programs. The performance characteristics of the serum and the platelet Hexosaminidase assays were compared, and also correlated with the results of targeted DNA analysis. The serum assay identified 29 carriers and the platelet assay identified 35 carriers for carrier rates of 1/36 and 1/29, respectively. One hundred sixty-nine samples (16.3%) were inconclusive by serum assay in marked contrast to four inconclusive samples (0.4%) by the platelet assay. Molecular analysis alone would have missed four of the 35 carriers detected by the platelet assay, yielding a false negative rate of 11.4% with a sensitivity of 88.6%. Based on the results of this study, platelet assay was superior to serum with a minimal inconclusive rate. Due to changing demographics of the Ashkenazi Jewish population, molecular testing alone in the setting of broad-based population screening programs is not sufficient, and biochemical analysis should be the assay of choice.

Background Multiple sclerosis (MS) is an autoimmune disease of the central nervous system, with a strong genetic component. Over 100 genetic loci have been implicated in susceptibility to MS in European populations, the most prominent being the 15:01 allele of the HLA-DRB1 gene. The prevalence of MS is high in European populations including those of Ashkenazi origin, and low in African and Asian populations including those of Jewish origin. Methods Here we identified and extracted a total of 213 Ashkenazi MS cases and 546 ethnically matched healthy control individuals from two previous genome-wide case-control association analyses, and 72 trios (affected proband and two unaffected parents) from a previous genome-wide transmission disequilibrium association study, using genetic data to define Ashkenazi. We compared the pattern of genetic risk between Ashkenazi and non-Ashkenazi Europeans. We also sought to identify novel Ashkenazi-specific risk loci by performing association tests on the subset of Ashkenazi cases, controls, probands, and parents from each study. Results The HLA-DRB1*15:01 allele and the non-HLA risk alleles were present at relatively low frequencies among Ashkenazi and explained a smaller fraction of the population-level risk when compared to non-Ashkenazi Europeans. Alternative HLA susceptibility alleles were identified in an Ashkenazi-only association study, including HLA-A*68:02 and one or both genes in the HLA-B*38:01-HLA-C*12:03 haplotype. The genome-wide screen in Ashkenazi did not reveal any loci associated with MS risk. Conclusion These results suggest that genetic susceptibility to MS in Ashkenazi Jews has not been as well established as that of non-Ashkenazi Europeans. This implies value in studying large well-characterized Ashkenazi populations to accelerate gene discovery in complex genetic diseases. Electronic supplementary material The online version of this article (doi:10.1186/s12881-015-0201-2) contains supplementary material, which is available to authorized users.

The Jews are an ancient and unique group of people linked by language, religion and customs in spite of their major geographical shifts, expulsions, forced conversions and massacres throughout their entire history. As a result of these historical events that led to repeated migration, the Jewish people became dispersed into various ethnic sub-groups. Between these ethnic groups exists heterogeneity, as well as some similarities, to the populations amongst whom they lived. Rare genetic diseases have been reported to be prevalent among the different groups of Jews, which for the most part can be explained by random genetic drift together with intra-familial marriages. In this publication, we will briefly discuss the origin of the various ethnic groups and some of the genetic diseases commonly found in them, with emphasis on the Ashkenazim, their prevalent genetic diseases and cancer susceptibility.

A founder effect can account for the presence of an allele at an unusually high frequency in an isolated population if the allele is selectively neutral and if all copies are identical by descent with a copy that either was carried by a founder individual or arose by mutation later. Here, a statistical test of both aspects of the founder-effect hypothesis is developed. The test is performed by a modified version of a program that implements the Slatkin-Bertorelle test of neutrality. The test is applied to several disease-associated alleles found predominantly in Ashkenazi Jews. Despite considerable uncertainty about the demographic history of Ashkenazi Jews and their ancestors, available genetic data are consistent with a founder effect resulting from a severe bottleneck in population size between a.d. 1100 and a.d. 1400 and an earlier bottleneck in a.d. 75, at the beginning of the Jewish Diaspora. The relatively high frequency of alleles causing four different lysosomal storage disorders, including Tay-Sachs disease and Gaucher disease, can be accounted for if the disease-associated alleles are recessive in their effects on reproductive fitness.

The frequency of several genes responsible for 'single-gene' disorders and disease predispositions is higher among Ashkenazi Jews than among Sephardi Jews and non-Jews. The disparity is most likely the result of founder effect and genetic drift, rather than heterozygote advantage. The more common Mendelian Ashkenazi Jewish genetic disorders are summarized, and examples of variable expressivity and penetrance, inconsistent genotype-phenotype correlation, and potential modifiers are presented. The importance of genetic counseling in both the pre- and post-test phases of population screening is emphasized.

Improvements in genetic testing technologies have led to the development of expanded carrier screening panels for the Ashkenazi Jewish population; however, there are major inconsistencies in current screening practices. A 2-year pilot program was launched in Atlanta in 2010 to promote and facilitate screening for 19 Jewish genetic diseases. We analyzed data from this program, including participant demographics and outreach efforts. This retrospective analysis is based on a de-identified dataset of 724 screenees. Data were obtained through medical chart review and questionnaires and included demographic information, screening results, response to outreach efforts, and follow-up behavior and preferences. We applied descriptive analysis, chi-square tests, and logistic regression to analyze the data and compare findings with published literature. The majority of participants indicated that they were not pregnant or did not have a partner who was pregnant were affiliated with Jewish organizations and reported 100 % AJ ancestry. Overall, carrier frequency was 1 in 3.9. Friends, rabbis, and family members were the most common influencers of the decision to receive screening. People who were older, had a history of pregnancy, and had been previously screened were more likely to educate others (all p

SummaryThe N370S mutation at the GBA locus on human chromosome 1q21, which causes Gaucher disease (GD), has a high frequency in the Ashkenazim and is the second-most-widespread GD mutation in the European non-Jewish population. A common ancient origin for the N370S mutation in the Ashkenazi Jewish and Spanish populations has been proposed on the basis of both a similar haplotype for associated markers and an age estimate that suggests that this mutation appeared several thousand years ago. However, a reappraisal of haplotype data, using the Risch formula properly along with a Luria-Delbrück setting of the genetic clock, allows identification of the likely origin of the N370S mutation in Ashkenazi Jews between the 11th and 13th centuries. This result is consistent with the estimated ages of other mutations that are frequent among Ashkenazim, with the exception of type II (Glu117Stop) factor XI deficiency, which is deemed to be >3000 years old, predating the separation of the Ashkenazi and Iraqi Jews. The present finding supports the hypothesis of a more recent origin for the N370S mutation and is consistent with both a founder chromosome transfer from Ashkenazim who assimilated in some European populations and a non-Jewish origin of the European N370S-bearing chromosomes.

Bloom's syndrome (BS) is a rare, autosomal recessive disease characterized by sun sensitivity, short stature, and predisposition to cancer. Although rare in the general population, BS is more common in the Ashkenazi Jewish population (German, 1993). The isolation of the gene for BS, known as BLM, has permitted the identification of mutations within the gene and the discovery that most BS individuals of Ashkenazi Jewish origin carry the identical 6-bp deletion/7-bp insertion at position 2,281 of BLM (blmAsh). We have developed a rapid method for detecting blmAsh based on restriction enzyme digestion of a PCR product containing the mutation. blmAsh creates a restriction site within the amplified fragment allowing distinction of normal and mutant DNAs. This method has been designed for use with genomic DNA or cDNA. Hum Mutat 11:175–178, 1998. © 1998 Wiley-Liss, Inc.

To the Editor: In a recent article, Risch et al. (2003) analyzed the frequencies of the various inherited disorders that are found in relatively high frequency among Ashkenazi Jews. By comparing three parameters—namely, the numbers of allelic mutations, allele frequency distribution, and estimated coalescence dates of mutations—Risch et al. (2003) demonstrated a similar pattern of these parameters between lysosomal storage disorders (LSDs) and 14 prevalent nonlysosomal disorders (NLSDs) that are prevalent among Ashkenazi Jews. Their conclusion, therefore, was that the LSDs are not unique in this population and the relatively high prevalence of LSDs stems from a genetic drift, rather than a selection process in favor of the LSDs in this population, as suggested elsewhere (Zlotogora et al. 1988). However, although we agree on the importance of the genetic drift to explain the high frequency of mutation in the Ashkenazi Jewish population, we still think that selective advantage for carriers of LSDs was apparently another important factor. Among >10,000 established gene loci (MIM Statistics, March 2003), >20 are responsible for disorders found with an increased prevalence among Ashkenazi Jews. As expected in a random process, there is no known relationship between most of the genes responsible for these disorders. The exceptions are the four prevalent LSDs among Ashkenazim—namely, Tay-Sachs disease (TSD [MIM 272800]), Gaucher disease (GD1 [MIM 230800]), Niemann-Pick disease (NPD [MIM 257200]), and mucolipidosis type IV (MLIV [MIM 252650])—in which the mutations are in genes that encode for enzymes from a common biochemical pathway. In all cases, the main storage substances are sphingolipids: GM2 ganglioside in TSD, glucosylceramide in GD, sphingomyelin in NPD, and various gangliosides in MLIV. A further indication of a nonrandom process is the number of mutations responsible for each disorder. As expected for random events, in almost all the NLSDs, one mutation is prevalent, and, if more than one mutation is found, its frequency is significantly 10% prevalent, when compared with the frequency of the major mutation. For instance, in NPD, three mutations are found in equal frequencies, and, in MLIV, there are two common mutations with a ratio of ∼2:1. In TSD, the ratio of the three common mutations is 73:18:3.5. In GD, the ratio between the two common mutations is 77:13 (Zlotogora et al. 2000). Furthermore, it should be noted that the data for allelic frequencies in the Risch et al. (2003) paper was partially based on the frequencies obtained by the Dor Yeshorim screening program, which uses mutation analysis. That program is aimed at the detection of heterozygotes for some eight prevalent severe disorders among Ashkenazim and is designed for a specific section of that population, the ultraorthodox community. We have shown elsewhere (Bach et al. 2001) that the frequency of TSD and allelic distribution of the three common mutations, in a sample of 32,000 individuals in the Dor Yeshorim program, is significantly different from the distribution found in the Ashkenazi population at large. We have seen a similar trend with other disorders as well, including familial dysautonomy (FD [MIM 223900]), MLIV, and others (G. Bach, unpublished data). Indeed, this community represents a relatively close section in which most individuals originated from specific locations in Europe. Thus, the data for allelic distribution in the Ashkenazi population, as reported in the article (Risch et al. 2003), does not fully represent the true picture. Risch et al. (2003) demonstrated a diverse geographic distribution of allelic mutations in some of the Ashkenazim with LSDs; certain mutations originated in Central Europe, whereas others originated in Eastern Europe. We suggest that this does not contradict a selection process, but that it may point to a secondary genetic drift. A well-known selection process by malaria in favor of heterozygotes has been demonstrated for sickle cell anemia (HBB [MIM 603903]) and is suspected for other blood disorders, such as thalassemia (HBB [MIM 141900]). If we focus on β thalassemia as an example, many mutations have been described in the populations that were exposed to malaria for centuries. Comparing the allelic distribution among Jews who originated from a relatively small geographic region, the mutations were significantly different in the Iranian, Turkish, and Iraqi parts of the Kurdistan Mountains (Rund et al. 1991). Nowadays, the high prevalence of thalassemia among the Kurdish Jews in Israel is due to several mutations, as a result of two processes: selection and genetic drift. Determining the forces that led to the present observations in the Ashkenazi Jews is complicated, and there is no clear data for the nature of the selection process in favor of the carriers of LSDs, if that process occurred. It was suggested that certain lung disorders (i.e., pneumonia and tuberculosis) conferred a heterozygous advantage for these disorders (Myrianthopoulos and Melnick 1977). If this is indeed the basis for the selection phenomenon or, in fact, any other similar environmental factor, the occurrence of different geographic origins of the various allelic mutations or different coalescence dates does not contradict a selection process but, rather, strengthens it. Regarding Ashkenazi Jews, although we have no clear evidence for the selection force, we can safely assume that the environmental factor lasted for centuries and that there is no reason to doubt that this selection force was effective in Central Europe as well as in the eastern part. Medical care for the Jewish people was not basically different in these regions. Thus, we would expect to find diverse distributions of allelic mutations for a selection process. Although the four LSDs are recessive, it can be postulated that, under extreme conditions, such as lung disorders, heterozygotes might undergo even a slight lysosomal storage of these substances, which might confer beneficial resistance to these conditions. To try to understand the past, one can look at the present and foresee the future. This can be done for genetic diseases found nowadays in populations whose living conditions are similar to those of the Ashkenazi Jews in Europe. One example is the Arab population living in the Middle East, in which the preference is for consanguineous marriages, as was the case for the Ashkenazi Jews. For the Jews who lived in Europe, like the Arabs living nowadays in Israel, further reasons to marry within the community were religious and geopolitical. In these populations, many genetic diseases are found with a high prevalence, and, although most are due to a single random mutation, others present a different distribution. For instance, among Arabs in Galilee, several diseases are found with an increased prevalence. On a molecular basis, in most cases, a single founder mutation explains the relatively high frequency for each disease. However, for other diseases—such as metachromatic leukodystrophy (MLD [MIM 250100]), Hurler syndrome (MPS1 [MIM 252800]), hyperoxaluria (HP1 [MIM 259900]), or ataxia telangiectasia (AT [MIM 208900])—many different mutations were found (Zlotogora 2002). In each case, all the patients were homozygous for a single mutation that was frequent, in general, in one village only. Another example is the high frequency of Mendelian disorders among the Bedouins of the Negev, owing to, in most cases, random founder mutations (Sheffield et al. 1998). However, Bardet-Biedl syndrome (BBS [MIM 209900]) is present among the Bedouins of the Negev in a very high prevalence, owing to mutations in three different genes. These observations, of either several mutations in the same gene or mutations in different genes responsible for the high prevalence of some genetic diseases in relatively small populations, cannot be explained as a random phenomenon. The possibility of a selective phenomenon must be raised, even though it has not yet been characterized. It may be expected that, in the future, with the expansion and mixing of the population, some of these mutations will be lost, whereas others will remain. Some mutations that are the result of genetic drift will be relatively prevalent in the general Arab population. One may wonder why the selection phenomenon was restricted primarily to the Ashkenazim and not to the non-Jewish people around them. Two, equally plausible, assumptions might explain this phenomenon. (a) The Jews in Europe, particularly in earlier periods (i.e., the 10th–17th centuries) lived for the most part in an extremely poor socioeconomic status with poor medical management. Thus, a selection force by heterozygous advantage might have been more effective for that population. (b) The genetic background of Jews was shown to be unique and different from that of other European people. It can be postulated that this particular genetic structure might have conferred a higher sensitivity or susceptibility to certain lung disorders, when compared with other people in the same region. We, therefore, conclude that the LSDs among Ashkenazim represent a unique group indicating a nonrandom phenomenon that might be explained by a selection process. This does not contradict a genetic drift, as was indicated by Risch et al. (2003)

Autosomal recessive nonsyndromic sensorineural hearing loss (ARNSHL) in Ashkenazi Jews, is mainly caused by mutations in the GJB2 and GJB6 genes. Here we describe a novel homozygous mutation of the LOXHD1 gene resulting in a premature stop codon (R1572X) in nine patients of Ashkenazi Jewish origin who had severe-profound congenital non-progressive ARNSHL and benefited from cochlear implants. Upon screening for the mutation among 719 anonymous Ashkenazi-Jews we detected four carriers, indicating a carrier rate of 1:180 Ashkenazi Jews. This is the second reported mutation in the LOXHD1 gene, and its homozygous presence in two of 39 Ashkenazi Jewish families with congenital ARNSHL suggest that it could account for some 5% of the familial cases in this community.

testing in the Ashkenazi Jewish population,aimed at reducing morbidity and mortality of breast/ovariancancer, is seemingly an obvious candidate for such a screeningprogram. In Ashkenazi Jews, three common, easily tested mu-tations account for the majority of deleterious alleles, effectivepreventive measures for

Disclaimer: This guideline is designed primarily as an educational resource for medical geneticists and other health care providers to help them provide quality medical genetic services. Adherence to this guideline does not necessarily assure a successful medical outcome. This guideline should not be considered inclusive of all proper procedures and tests or exclusive of other procedures and tests that are reasonably directed to obtaining the same results. In determining the propriety of any specific procedure or test, the geneticist should apply his or her own professional judgment to the specific clinical circumstances presented by the individual patient or specimen. It may be prudent, however, to document in the patient's record the rationale for any significant deviation from this guideline.

In the community of the Orthodox Jews most of the marriages are arranged a screening program that is aimed at preventing the marriage of two carriers of autosomal recessive disorders is conducted by the Dor Yesharim organization. A random sample of 6,076 individuals of the Orthodox Jewish Ashkenazi community, were screened for the five mutations common in Ashkenazi patients (delta F508, W1282X, G542X, N1303K, 3849 + 10Kb C--T). Two hundred thirty-two carriers were identified, giving a heterozygote frequency of 1:26. The relative frequencies of the individual mutations in the general population were comparable to those in the patients.

Iranian Jews represent an ancient community with a very high degree of inbreeding. Although the community remained relatively isolated, it had strong ties with Babylonian Jewry in Iraq. Several genetic disorders have been reported to be frequent among Iranian Jews, in particular, corticosterone methyloxydase deficiency type II, polyglandular syndrome, and rimmed vacuole myopathy. Based on the data collected in our clinic, recessive and dominant deafness also appear to be frequent. Other diseases, such as beta-thalassemia, achromatopsia, colobomatous microphthalmia, Dubin-Johnson syndrome, and congenital myasthenia gravis, were frequent in both the Iranian and Iraqi Jewish communities. The place of origin of the families within Iran and the results of molecular studies suggest some reason(s) for the high frequency of these disorders among Iranian Jews. While the high frequency of some of the disorders, such as corticosterone methyloxydase deficiency type II, represents a founder effect, in other diseases (such as beta-thalassemia) it was secondary to heterozygote advantage.

To the Editor: We read with interest and much concern the recent recommendation of the College regarding carrier screening in individuals of Ashkenazi Jewish (AJ) descent (Genet Med 2008;10: 54 –56). Specifically, we felt that Recommendation 4, “if only one member of a couple is of AJ background, testing should still be offered,” is quite problematic. As stated in the Guidelines, the cumulative probability of being a carrier for one of the conditions in the panel is between 20 and 25%. One in 4 or 1 in 5 couples where only one member is of AJ descent will be identified as at increased risk to have an affected child and offered testing for that specific condition for the non-AJ partner. The screening of the non-AJ partner for the mutations that occur in the AJ population is an exercise in unknown probabilities (Table 1). Since the frequency of those mutations that occur more often in the AJ population is unknown in non-AJ populations, there is no way to revise a couple’s risk after screening the non-AJ member for the AJ mutations. Counseling a couple that the non-AJ member does not carry any of the AJ mutations does not provide much solace (or information) regarding their risk for a child with one of the AJ genetic conditions. In the case of cystic fibrosis (where gene frequencies are known in various populations) and in the case of Tay-Sachs disease (where enzyme analysis is informative regardless of ethnicity) the Practice Guidelines do provide useful information that would aid a family in their decision-making process. Even without testing the non-AJ member, counselors can be reassuring to those couples where the AJ member is a carrier for Dysautonomia, Bloom syndrome, or Mucolipidosis IV, as these conditions are either extremely rare or unreported in non-AJ populations. So the question remaining (with the exception of cystic fibrosis and Tay-Sachs screening) is what do we accomplish by the implementation of these Guidelines in couples where only one member is of AJ descent? Michael L. Begleiter, MS, CGC Janda L. Buchholz, MS, CGC Andrea M. Atherton, MS, CGC Lee Z. Mays, MS, CGC Molly M. Lund, MS, CGC Meghan E. Strenk, MS Genetics, Dysmorphology and Metabolism, The Children’s Mercy Hospitals & Clinics, Kansas City, Missouri, The University of Missouri-Kansas City, School of Medicine, Kansas City, Missouri

This work was funded in part by a grant from the National Foundation for Jewish Genetic Diseases. We thank Dr. Robert Pergolizzi (North Shore University Hospital, Manhasset, NY), for the automated sequencing, and the NIGMS Human Genetic Mutant Cell Repository (Camden, NJ), for generously supplying the control cell lines used in this study.

Summary Several deleterious and lethal autosomal recessive genes appear to exist in equilibrium with their normal alleles at a variety of stable, or near stable frequencies of considerable antiquity. One person in 25 is, for instance, a carrier of the Tay-Sachs gene among Ashkenazi Jews, compared with 1 in 300 among Sephardic and Oriental Jews and non-Jews. The explanations offered for t his phenomenon have generally not been entirely satisfactory. It has been shown that parents replace fortuitous infant and childhood deaths with, on average, approximately two surviving sibs each. When mutation rates are low, this practice, which has also been shown to occur among other animals, can maintain considerable variations in the stable incidence of autosomal recessive disease, should such ethnic polymorphism arise through genetic drift, the founder effect or hitch-hiking. High mutation rates would appear to preclude ethnic variations in the stable incidence of genetic disease.

Hunter disease in Israel occurs among Ashkenazi, Oriental, and Sephardic Jews and is by far more frequent than Hurler disease. None of the other mucopolysaccharidoses has been diagnosed in Ashkenazi Jews. The possibility of Hunter disease being a “Jewish” disease is discussed.