Search

Hyperphenylalaninemia (HPA) is a group of diseases characterized by a persistent elevation of phenylalanine levels in tissues and biological fluids. The most frequent form is phenylalanine hydroxylase deficiency, causing phenylketonuria (PKU). Among 159 Israeli patients (Jews, Muslim and Christian Arabs and Druze) with HPA, in whom at least one of the mutations was characterized, a total of 43 different mutations were detected, including seven novel ones. PKU was very rare among Ashkenazi Jews and relatively frequent among Jews from Yemen, the Caucasian Mountains, Bukhara and Tunisia. The mutations responsible for the high frequency were: exon3del (Yemenite Jews), L48S (Tunisian Jews) and E178G, P281L and L48S (Jews from the Caucasian Mountains and Bukhara). Among the non-Jewish Israeli citizens, the disease was relatively frequent in the Negev and in the Nazareth vicinity, and in many localities a unique mutation was detected, often in a single family. While marked genetic heterogeneity was observed in the Arab and Jewish populations, only one mutation A300S, was frequent in all of the communities. Several of the other frequent mutations were shared by the non-Ashkenazi Jews and Arabs; none were mutual to Ashkenazi Jews and Arabs. [ABSTRACT FROM AUTHOR]

As a result of the preference for consanguineous/endogamous marriages, the Israeli Arab population is composed of isolated communities with relatively frequent autosomal recessive (AR) conditions in each community. Clinical diagnosis of affected individuals has uncovered the pathogenic variants throughout the years. We investigated the diversity of pathogenic AR variants in a single village in northern Israel by exome analysis of 50 random, healthy adults descendants of the founders. Only likely pathogenic and pathogenic variants in known AR genes were selected. In this study 48 AR variants were found, of which 12 had been previously diagnosed in patients from this village, and for 11 with a frequency compatible with the frequency already known. Among the other 36 variants, 12 had been previously diagnosed in affected individuals in other Arab communities in Israel and 24 variants had not been previously characterized in this population. Of the 35 variants associated with conditions of moderate-severe medical consequences, only eight were known previously in this village. These findings emphasize the importance to better delineate the conditions at risk in a defined community, in particular for the development of preventive measures such as screening tests for reproductive couples, and for genetic counseling., (© 2021 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Several autosomal recessive disorders that are found among Arabs in Israel were also reported in Saudi Arabia. In a sytematic review of all the variants responsible for autosomal recessive disorders among Muslim Arabs Israel and in Saudi Arabia, 47 shared variants were found, many being known founder variants in both populations. Among the 21 shared variants that were reported among Bedouins 14 were founder variants representing 14% founder/assumed founder variants known in the Bedouins. Many of the common variants are ancient having a Bedouin origin probably linked to the migration from the Saudi Peninsula. It is probable that a similar phenomenon occurred along the route of the Bedouin migrations and indeed some of these variants are present in the corresponding populations., (© 2021 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

The founder variant DHCR7:c.964-1G>C causing autosomal recessive Smith-Lemli-Opitz (SLOS) was introduced into the Israeli preconception carrier program for Ashkenazi Jews in 2017 because of the high carrier frequency in this population (2.3%). Other disease-causing variants in DHCR7 are relatively rare in Israeli population. Discrepancy between the carrier frequency and disease prevalence raises the question of the actual risks for affected offspring for couples detected by the screening program. We performed a literature review of all relevant publications regarding homozygous DHCR7:c.964-1G>C fetuses/patients. We also collected clinical data about couples identified in the national screening program, including reproductive history. Out of 32 homozygous fetuses, six died in utero, 11 pregnancies were terminated during second trimester, and 15 children were born. All died between first days of life till 3 months of age. Reproductive history of SLOS-at-risk couples showed that after correction for ascertainment bias, out of 61 pregnancies, there was an absence of affected fetuses/children and an excess of miscarriages even if assumed that all the homozygous fetuses were miscarried. Out of these, eight families were Israelis, they had a total of one sick child, 21 healthy children, and 21 miscarriages. Our observations support the previous knowledge that homozygosity for c.964-1G>C in DHCR7 leads to a severe phenotype or early miscarriage. An unexpected observation was the excess of early miscarriages. This phenomenon is unclear and awaits further studies.

Reproductive carrier screening started in some countries in the 1970s for hemoglobinopathies and Tay-Sachs disease. Cystic fibrosis carrier screening became possible in the late 1980s and with technical advances, screening of an ever increasing number of genes has become possible. The goal of carrier screening is to inform people about their risk of having children with autosomal recessive and X-linked recessive disorders, to allow for informed decision making about reproductive options. The consequence may be a decrease in the birth prevalence of these conditions, which has occurred in several countries for some conditions. Different programs target different groups (high school, premarital, couples before conception, couples attending fertility clinics, and pregnant women) as does the governance structure (public health initiative and user pays). Ancestry-based offers of screening are being replaced by expanded carrier screening panels with multiple genes that is independent of ancestry. This review describes screening in Australia, Cyprus, Israel, Italy, Malaysia, the Netherlands, Saudi Arabia, the United Kingdom, and the United States. It provides an insight into the enormous variability in how reproductive carrier screening is offered across the globe. This largely relates to geographical variation in carrier frequencies of genetic conditions and local health care, financial, cultural, and religious factors., (© 2019 John Wiley & Sons, Ltd.)

The Israeli population genetic screening program for reproductive purposes, is a population-specific screening that includes all known, severe diseases and relatively frequent in a specific population (carrier frequency at or above 1:60 and/or disease frequency at or above 1 in 15,000 live births). The carrier screening program is free of charge and offers testing according to disease frequency in the different groups within the population.The extraordinary technical changes that occurred in the last decade as well as the changes in the type of marriages within the Israeli population necessitate a revision in the basis of the program.The screening should include instead of only the relatively frequent variants, all the variants that were reported among patients causing a severe disease for which the natural history is well known without regard of their frequency. The population-specific screening that determine which variants are included according to the origin of the couple should be abandoned for a general screening including either all the Jewish population or all the Israeli Arab population.

The Israeli population mainly includes Jews, Muslim and Christian Arabs, and Druze. Data on genetic diseases present in the population have been systematically collected and are available online in the Israeli national genetic database. Among the Israeli Arabs in December 31 2018, the database included molecular data on six diseases relatively frequent in the whole population: thalassemia, familial Mediterranean fever (FMF), cystic fibrosis, deafness, phenylketonuria or congenital adrenal hyperplasia as well as data on 632 autosomal recessive diseases among Muslim Israeli Arabs, 52 among the Christian Arabs and 79 among Druze. A single variant was characterized in 590 out of the 771 genes causing disorders in which the molecular basis was known. Many of the variants reported among Arabs in Israel are novels, most being found in one community only. Some variants are ancient and for instance, consistent with the migration history, several variants are found in the Bedouins from the Negev as well as from the Arab peninsula. In the 181 other disorders more than one variant was characterized either in the same gene or in more than one gene. While it is probable that most of these cases represent random events in some cases the reason may be a selective advantage to the heterozygotes.

Purpose: The aim of the study was to compare the data for mutations related to clinical disorders reported among Ashkenazi Jewish patients in the Israeli National Genetic Database (INGD) with variants included in the Genome Aggregation Database (gnomAD)., Methods: We extracted data for mutations claimed to cause disorders reported among Ashkenazi Jews from the INGD and searched gnomAD for each of them. We compared the allele frequency of each variant in Ashkenazi Jews with that of other delineated populations., Results: Of the 58 INGD-reported mutations related to autosomal-dominant disorders, 19 were present in gnomAD (32.8%). Of the 309 mutations related to autosomal-recessive disorders, 240 (77.7%) were variants found in gnomAD. Of these variants, 202 (84.2%) were documented among one or more Ashkenazi individuals. At this point in the INGD, there are 168 Ashkenazi assumed founder mutations in 128 different genes corresponding to 111 autosomal-recessive disorders., Conclusion: Integration of information on mutations among Ashkenazi Jews extracted from the INGD with their population frequency recorded in gnomAD is important for effective straightforward molecular diagnosis as well as for targeted carrier screening either for reproductive decision-making or for implementation of disease-modifying behavior.

Objectives: In a single Muslim village in Israel, established about 300 years ago by a small number of founders, a longitudinal study was conducted on the types of marriages and their effects on family planning, with the age at which a woman had her first child and the size of the family assessed., Methods: The information for the analysis was extracted from a detailed database including individuals residing in and originating from the village., Results: A shift from the practice of marrying a close relative, in particular patrilateral parallel first-cousin marriages, to marrying a more remotely related individual was observed during the study period. Another major change was a significant reduction in the mean number of children born per woman from 8.7 among women born between 1930 and 1939 to 4.7 among those born between 1960 and 1969. In families in which the parents were biological relatives, the number of children was always higher than in families in which the parents were unrelated. The mean age of the mother at the birth of her first child progressively increased during the study period from 20.9 to 23.7 years. The maternal age was always higher when the spouses were from different villages than when they were biological relatives, either being first cousins or more distantly related., Conclusions: Significant sociodemographic changes were observed during the course of the last 50 years. However, the consequences of the long-lasting isolation of the population remain and still exert an important effect on present-day medical problems in the village., (© 2014 S. Karger AG, Basel)

Background: Enumeration of T cell receptor excision circles (TREC) was recently adopted as a neonatal screening assay for severe combined immunodeficiency (SCID). Enumeration of kappa-deleting recombination excision circle (KREC) copy numbers can be similarly used for early assessment of B cell lymphopenia., Objective: To assess the ability of TREC and KREC counts to identify patients with combined T and B cell immunodeficiency in a pilot study in Israel., Methods: We studied seven children born in Israel during the years 2010-2011 and later diagnosed with SCID, and an additional patient with pure B cell immunodeficiency. TREC and KREC in peripheral blood upon diagnosis and in their neonatal Guthrie cards were analyzed using real-time quantitative polymerase chain reaction, as were Guthrie cards with dried blood spots from healthy newborns and from normal and SCID-like controls., Results: The first features suggestive of SCID presented at age 3.1 +/- 2.4 months in all patients. Yet, the diagnosis was made 4.1 +/- 2.9 months later. Their TREC were undetectable or significantly low at their clinical diagnosis and in their originally stored Guthrie cards, irrespective of the amount of their circulating T cells. KREC were undetectable in six SCID patients who displayed B cell lymphopenia in addition to T cell lymphopenia. KREC were also undetectable in one patient with pure B cell immunodeficiency., Conclusions: TREC and KREC quantification are useful screening tests for severe T and B cell immunodeficiency. Implementation of these tests is highly important especially in countries such as Israel where a high frequency of consanguinity is known to exist.

The Israeli population mainly includes Jews, Muslim and Christian Arabs, and Druze In the last decade, data on genetic diseases present in the population have been systematically collected and are available online in the Israeli national genetic database ( http://www.goldenhelix.org/server/israeli ). In the non-Jewish population, up to 1 July 2010, the database included molecular data on six diseases relatively frequent in the whole population: thalassemia, familial Mediterranean fever (FMF), cystic fibrosis, deafness, phenylketonuria and congenital adrenal hyperplasia, as well as data on 195 autosomal recessive diseases among Muslim Israeli Arabs, 11 among the Christian Arabs and 31 among Druze. A single mutation was characterized in 149 out of the 238 rare disorders for which the molecular basis was known. In many diseases, mutation had never been observed in any other population and was present in one family only suggesting that it occurred as a de novo event. In other diseases, the mutation was present in more than one community or even in other populations such as Bedouins from the Arab peninsula or Christians from Lebanon. In the 89 other disorders, more than one mutation was characterized either in the same gene or in more than one gene. While it is probable that most of these cases represent random events in some cases such as Bardet Biedl among the Bedouins, the reason may be a selective advantage to the heterozygotes.

Background: Ultrasound examination of the fetus enables diagnosis of many major malformations during pregnancy, providing the possibility to consider termination of the pregnancy. As a result, in many cases the incidence of malformations at birth does not represent their true incidence., Objectives: To determine the impact of prenatal diagnosis and pregnancy termination on the relative incidence of malformations at birth among Jews and Muslim Arabs in Israel., Methods: Data on selected major malformations in 2000-2003 were collected from the two large central databases of the Ministry of Health and the Central Bureau of Statistics which contain information regarding births, stillbirths and terminations of pregnancies., Results: For many malformations the total incidence was much higher than the incidence at birth. For almost all of the malformations studied, the total incidence was higher in Muslims than in Jews and the differences were further accentuated among the liveborn because of the differences in the rate of pregnancy terminations., Conclusions: In order to detect possible influences of environmental or genetic factors on major malformations in Israel, it is critical to look at data including pregnancy terminations, stillbirths and live births.

Background: Retinitis pigmentosa (RP) is the most common form of hereditary retinal degeneration. At least 32 genes and loci have been implicated in non-syndromic autosomal recessive RP. Progressive rod-cone degeneration is a canine form of autosomal recessive retinal degeneration, which serves as an animal model for human RP, and is caused by a missense mutation of the PRCD gene. The same homozygous PRCD mutation has been previously identified in a single human RP patient from Bangladesh. To date, this is the only RP-causing mutation of PRCD reported in humans., Methods: The cause of the high incidence rate of autosomal recessive RP in an isolated Muslim Arab village in Northern Israel was investigated by haplotype analysis in affected families. The underlying mutation was detected by direct sequencing of the causative gene, and its prevalence in affected and unaffected individuals from the village was determined. Patients who were homozygotes for this mutation underwent ophthalmic evaluation, including funduscopy and electroretinography., Results and Conclusions: The identification of a novel pathogenic nonsense mutation of PRCD is reported. This founder mutation was found in a homozygous state in 18 patients from nine families, and its carrier frequency in the investigated village is 10%. The mutation is associated with a typical RP phenotype, including bone spicule-type pigment deposits and non-recordable electroretinograms. Additional findings include signs of macular degeneration and cataract. The identification of a second pathogenic mutation of PRCD in multiple RP patients confirms the role of PRCD in the aetiology of RP in humans.

National and ethnic mutation databases (NEMDBs) are emerging online repositories, recording extensive information about the described genetic heterogeneity of an ethnic group or population. These resources facilitate the provision of genetic services and provide a comprehensive list of genomic variations among different populations. As such, they enhance awareness of the various genetic disorders. Here, we describe the features of the ETHNOS software, a simple but versatile tool based on a flat-file database that is specifically designed for the development and curation of NEMDBs. ETHNOS is a freely available software which runs more than half of the NEMDBs currently available. Given the emerging need for NEMDB in genetic testing services and the fact that ETHNOS is the only off-the-shelf software available for NEMDB development and curation, its adoption in subsequent NEMDB development would contribute towards data content uniformity, unlike the diverse contents and quality of the available gene (locus)-specific databases. Finally, we allude to the potential applications of NEMDBs, not only as worldwide central allele frequency repositories, but also, and most importantly, as data warehouses of individual-level genomic data, hence allowing for a comprehensive ethnicity-specific documentation of genomic variation.

The principle deeds of genetics in Israel consist of a wide array of disciplines including agriculture, nutrients, biotechnology, pharmacology and pharmacogenetics, pertaining to criminal as well as medical aspects. In the scope of this state of the art historical review, the authors emphasize the medical issues. The initial stimulus for genetic studies and medical awareness among the various ethnic populations in Israel was the immigration, in the early 1950s, of over a million Jewish immigrants from more than 100 countries from all continents. It was soon recognized that frequencies of genetic diseases differed markedly among the various communities, serving as a trigger for studying and managing these populations. In this state of the art historical review, particular emphasize was given to the historical events concerning genetics in the land of Israel, as well as in the state of Israel. Highlights of genetic diversity of the various ethnic and sub-populations are added, along with the advances and major achievements of the human genetics discipline in the state of Israel.

The Israeli National Genetic Database http//www.goldenhelix. org/israeli is a continuously updated depository on monogenic genetic disorders that are present in the various Israeli populations. It provides the means of obtaining information for clinical purposes, genetic counseling and research.

The National and Ethnic Mutation Databases (NEMDBs) are continuously updated mutation depositories that contain extensive information on the described genetic heterogeneity of an ethnic group or population. Here, we report the construction of the Israeli National Genetic database (Available at: www.goldenhelix.org/israeli; Last accessed: 20 April 2007) to document the sheer genetic heterogeneity found in the Jewish and non-Jewish populations in Israel. The database is built and maintained online using a newly developed customized version of the ETHNOS platform. The Israeli NEMDB is the richest in information among individual NEMDB, containing summaries of 347 genetic disorders studied for the Israeli populations with numerous relevant references and links to the respective Online Mendelian Inheritance in Man (OMIM) entries. Summaries can be selected from an alphabetical summary index or queried using a keyword-based search functionality. An easy-to-use query interface provides access to the over 600 entries on allelic and carrier frequencies of the different mutations responsible for certain inherited disorders in the Jewish and non-Jewish populations, although such documentation is not as extensive as in the other ETHNOS-based NEMDBs. Also, the Israeli NEMDB provides a comprehensive listing of all laboratories providing molecular genetic testing services in Israel with a separate query interface for the user to select which genetic service is provided to a certain laboratory. The Israeli NEMDB is a useful user-friendly and extendable online resource for genetic services in Israel, while the modified version of the ETHNOS software can be particularly useful for similar projects in other populations., (Copyright 2007 Wiley-Liss, Inc.)

Background: The national program for the prevention of Down syndrome includes screening (using the triple test) and invasive diagnostic tests in women at risk for a Down syndrome pregnancy. However, despite the program, the majority of Down syndrome infants are born alive (approximately 1/1000 live births)., Objectives: To determine whether the relatively high incidence of Down syndrome at birth in Israel is the result of failure of the preventive program or due to informed choices of the mothers., Methods: We conducted a retrospective study using the national registry of Down syndrome for the years 1997 and 2004, according to the mothers' religion and place of residence and the reasons for prenatal diagnosis., Results: Most of the babies affected with Down syndrome are born in religious or traditional conservative communities where termination of pregnancy is usually not an option., Conclusions: In a pluralistic society like Israel with its diverse communities and dissimilar religious backgrounds and traditions, the different attitudes concerning utilization of the national program should be respected. It is necessary to tailor different approaches and solutions for the various ethnic and religious communities according to their need.

In a Muslim Arab village, relatively isolated because of the preference of consanguineous marriages, we studied the fate of 12 mutations in 5 different genes. The study was based on carriers detected among relatives of affected patients and of carriers discovered in a random sample of 424 adults. Most of the mutations have been introduced by a carrier(s) originating from another village, but a few have been de novo events. Mutations that are very frequent in the entire village were introduced soon after the foundation of the village. Examples of such mutations are [GBJ2, 35Gdel] and [MEFV, M680I], with a carrier frequency of 7.8% and 6.2%, respectively. Many of the other mutations that are rare were introduced recently into the village and are frequent only among the descendants of the first couple carrying the mutation. For instance all the carriers of [ARSA, Q190H], responsible for metachromatic leukodystrophy, were found among the 218 descendants of a couple who were living in the village 4 generations ago. Since the village is typical for the region this study allows for some general conclusions to be drawn. In a population with a high degree of inbreeding the diagnosis of a single family with a patient(s) affected with a recessive disorder points to a recent event, while the finding of a rare disease in several families from an inbred population points to an older mutation. Mutations are often "exported" from one population to another by marriage. In the new inbred population this novel mutation will either be lost or will become frequent as the result of a founder effect. These observations are important for genetic counselling in the case of a recent mutation, since only the descendants of the founder couple are at risk, while in the case of older mutations the risk may be for the entire village. In the case of those frequent ancient mutations, the risk for a relative of an affected individual will be similar whether he marries a close relative or any random individual in the village.

Nonsyndromic mental retardation (NSMR) is the diagnosis of exclusion in mentally retarded individuals without additional abnormalities. We have recently identified a protein-truncating mutation, G408fsX437, in the gene CC2D1A on chromosome 19p13.12 in nine consanguineous Israeli Arab families with severe autosomal recessive NSMR, and have developed a comprehensive prevention program among the at-risk population in the village. The subjects tested were healthy women who were invited to undergo the genetic screening test as a part of their routine pregnancy monitoring. One hundred and seventeen subjects reported a family history positive for mental retardation. We tested 524 pregnant or preconceptional women and found 47 carriers (approximately 1/11), whose spouses were then recommended to undergo testing. We identified eight carrier couples, who were given genetic counseling and offered prenatal diagnosis. Of all the marriages, 28.6% were consanguineous; 16.5% of the total were between first cousins. The high prevalence of the mutation can be explained both by the founder effect owing to the generally high consanguinity rate among the inhabitants of the village, and also because two families with excessive numbers of mentally retarded offspring were unacceptable as marriage partners by the rest of the families. This is the first example of the establishment of a large-scale genetic screening program for autosomal recessive NSMR, which was made possible owing to the high frequency of the specific causative mutation in this isolated population.

Background: Open neural tube defects are among the most common severely disabling birth defects. Secondary prevention by early diagnosis during pregnancy and abortion of affected fetuses lead to a marked reduction of NTD incidence at birth. For primary prevention of these defects, in August 2000 the Israel Ministry of Health issued guidelines recommending a daily 0.4 mg folic acid supplement for all women in their childbearing years with special emphasis on the 3 months preceding conception and the first trimester of pregnancy., Objectives: To compare the epidemiologic characteristics of NTD in Israel before and after the guidelines for folic acid supplementation., Methods: A national registry of NTD was begun in 1999. Since the Ministry of Health published the recommendation for folic acid supplementation in mid-2000, the years 1999-2000 represent the status prior to the recommendation and the years 2002-2004 the status after., Results: A marked decline in the rate of spina bifida was observed in the last 3 years (from 4.9 to 2.7 per 10,000 live births among Jews and 9.5 to 6.2 among Arabs and Druze). There was no apparent reduction for anencephaly., Conclusions: Following the Ministry of Health guidelines on folic acid supplementation for women in the reproductive age, a marked reduction in the rates of NTD was observed. In light of this apparent success, continuous efforts should be made to increase the percentage of women taking the supplementation and, especially, to introduce folic acid fortification.

Genetic disorders are frequent in the Arab population of Israel, mainly because of the preference for consanguineous marriages. Many of the inherited diseases are present with a high frequency only in a limited region or a single village. It is therefore not surprising that, in each of the villages, a different distribution of genetic diseases is found; thus, a detailed knowledge of the genetic disorders present in each village is of utmost importance for genetic counseling. As a direct consequence of these observations two community genetics clinics were opened as a pilot project to study their impact on the population to be served. The use of a computer database allowed for easier and more accurate genetic counseling. There were almost 1,500 visits in the 4-year period since the introduction of the services. During the years an increase in the mean number of consultations per clinic as well as a change in the type of referrals was observed. There was an increasing proportion of clinics that were made at a time in which genetic counseling allow for primary prevention. The presence of a genetic counselor in the village clinic allows for better and closer contacts with the family physician., (Copyright 2006 Wiley-Liss, Inc.)

In Israel, as in several countries of the Mediterranean basin, beta-thalassemia is frequent among Arabs, and many different mutations in the beta globin gene have been identified. In a single Arab village, three different thalassemia mutations, as well as the sickle-cell mutation, were characterized. Using genealogical data as well as the results of screening in the village population, we were able to demonstrate/speculate on how mutations were introduced into the village and how they later expanded. The sickle-cell mutation became particularly prevalent in the village as the result of a founder effect due to a preference for consanguineous marriages., (Copyright 2005 Wiley-Liss, Inc)

Genetic diseases are relatively prevalent among the Arab population, and are a significant cause of morbidity and mortality in this population. The relative high rate of genetic diseases among the Arabs in Israel is a direct result of very high rates of consanguinity. In order to reduce the frequency of congenital malformations/inherited diseases, it is important to choose combined strategies, including efforts focused on health education and health promotion, with an emphasis on the medical consequences of marriages within the family. Primary prevention is conducted by genetic counseling prior to marriage or prior to the first pregnancy and secondary prevention focuses on early genetic screening during the pregnancy. In order to provide the necessary tools for such a program, genetic research must first characterize the common genetic diseases in the small communities, and identify their responsible mutations.

The aim of this research was to determine the relative prevalence at birth of major malformations among the different religious communities in Israel as a way to better understand their causes. We collected data on malformations present among liveborn infants in a 10-year period from the national registry of birth defects according to the religious affiliation. In a total of 1,203,763 liveborn infants, the prevalence of major malformations was in a similar range among Jews and Christians and much higher among Muslim and Druze. These observations may be explained by differences between these communities, in particular, the rates of consanguinity and of therapeutic abortions. The Muslim and Druze communities in Israel are those with the highest consanguinity rates and the lowest rates of termination of pregnancies when a malformation is diagnosed. Analysis of the differences in the rate of malformations at birth in different communities is important for Public Health planning. It may also help to delineate causes and serve as the basis for research., (Copyright 2003 Wiley-Liss, Inc.)

Background: Infant mortality in Israel is twofold higher among non-Jews than Jews., Objectives: To determine the impact of congenital malformations and Mendelian diseases on infant mortality., Methods: We compared the causes of infant mortality in a 4 year period among Jewish and non-Jewish Israeli citizens. Classification was done by analyzing all the death reports according to whether or not the child had any known major malformation, Mendelian disease and/or a syndrome, irrespective of the immediate cause of death., Results: The infant mortality among non-Jews was double that among Jews (9 versus 4.4 per 1,000 live births). The rate of children with malformations/genetic syndromes was 3.1 times higher among non-Jews than among Jews (2.94 vs. 1.25 per 1,000 live births). The most significant difference was in the rate of Mendelian diseases, which were 8.3 times more frequent in non-Jewish children (0.16 vs. 1.33 per 1,000 live births respectively). A Mendelian disease was diagnosed in almost 15% of the non-Jewish infants and in less than 5% of the Jewish infants., Conclusions: The most striking difference between the Jewish and non-Jewish infants was the incidence of congenital malformations and Mendelian diseases parallel to the differences in the consanguinity rates between the two populations.

Leber congenital amaurosis (LCA) is a genetically heterogeneous autosomal recessive condition responsible for congenital blindness or greatly impaired vision since birth. Eight LCA loci have been mapped, but only six out of eight genes have been hitherto identified. A genome-wide screen for homozygosity was conducted in a large consanguineous family originating from Palestine, for which no mutation was found in any of the six known LCA genes and that excluded the LCA3 and LCA5 loci. Evidence for homozygosity, however, was found in all affected patients of the family on chromosome 1q31, a region in which the human homologue of the Drosophila melanogaster crumbs gene (CRB1) has been mapped. Consequently, we proposed a hypothesis that the disease-causing mutation in this family might lie in an unexplored region of this LCA gene. As a matter of fact, while no mutation was found in any of the 11 CRB1 exons originally reported, we identified a 10-bp (del 4121-4130) deletion segregating with the disease in a later reported 12th exon lying in the 3' end of the gene. Interestingly, this deletion disrupts an amino acid sequence that was shown to be crucial for the function of the protein in the Drosophila counterpart (CRB).

Background: Open neural tube defects are among the most common malformations of the fetus. Secondary prevention by early diagnosis during pregnancy and abortion of affected fetuses result in a marked reduction of NTD incidence at birth. The dramatic effect of folic acid for primary prevention of these defects led to recommendations for folic acid supplementation in women of reproductive age., Objective: To describe the epidemiologic features of NTD in Israel in 1999-2000., Methods: A national registry of NTD was begun in 1999. During the years 1999-2000, a non-syndromic NTD was diagnosed in at least 394 pregnancies (166 anencephaly, 166 spina bifida, 43 encephalocele, and 19 with other types of NTD). The religious-ethnic affiliation was known in 392 cases (209 Jews and 183 non-Jews)., Results: Despite a marked decline in the rate of NTD at birth in the last few decades, the total rates during pregnancy did not change significantly, demonstrating that the changes were secondary to termination of affected pregnancies. At birth, NTD were almost four times more frequent among non-Jews (3.6 per 10,000 live births for anencephaly and 5.9 for spina bifida) than among Jews (anencephaly 1/10,000 live births, spina bifida 1.4/10,000 live births). The complete data of the registry showed an approximately twofold difference in the overall rates during pregnancy between Jews (anencephaly 5.3, spina bifida 4.6, total 11/10,000 live births) and non-Jews (anencephaly 8.8, spina bifida 10.3, total 22.3/10,000 live births). The registry demonstrated that the significant differences in NTD incidence observed at birth between Jews and non-Jews are secondary to a combined effect of a higher frequency of the malformations among non-Jews and a lower proportion of termination of affected pregnancies among non-Jews., Conclusions: The data presented here will serve as a basis for evaluating the impact of the Ministry of Health recommendations for folic acid supplementation on the incidence of NTD.

Objective: To determine the importance of various factors on the decisions whether to terminate or continue a pregnancy after an abnormal result., Methods: The decisions of 1467 women who had an abnormal result after an invasive prenatal test were examined according to their religion, the time of diagnosis and the severity of the disorder., Results: When the examinations were performed by chorionic villus sampling (CVS) among both Jews and non-Jews most of the women opted to terminate the affected pregnancy. After amniocentesis the rate of termination of pregnancy was still very high among cases in which Down syndrome or other significant chromosomal aberrations were diagnosed among Jews. For all the other diagnostic groups either among Jews or non-Jews there was a significant proportion of the cases in which the women decided to continue the pregnancy. A significant exception about the decisions of the couples was in the case of hemoglobinopathy-affected pregnancies among Arabs since both after CVS and amniocentesis many women often decided to continue the pregnancy., Conclusion: The main factor in the decision to terminate or continue the pregnancy is the severity of the disorder diagnosed. However, among Arabs other factors are important, in particular the time at which the diagnosis is made., (Copyright 2002 John Wiley & Sons, Ltd.)

Among 1,875 couples from one Muslim village, 374 (20%) marriages were between first cousins. Among women born after 1920, the highest rates of first-cousin marriages were observed among those born between 1940-1959 (26%) and this pattern declined in the last two decades. The majority of first-cousin marriages were between offspring of brothers. Analyzed by 20-year periods, the pattern of first-cousin marriages changed as the proportion of marriages between brothers' children decreased from 75% to 44%. Over the study period, more than 70% of marriages were between individuals born in the village and related to some degree. Examination of the marriages in which both spouses were born in the village demonstrated a preference to marry within the extended family; 68% of the women married a man with the same family name. Since the creation of the Israeli State, there have been significant changes among Israeli-Arab citizens. However, these data demonstrate that the tradition of marrying a relative remains central, although some changes in marriage preference have occurred., (Copyright 2002 Wiley-Liss, Inc.)

In the review of the literature, 71 different autosomal recessive diseases have been delineated that are relatively frequent among Palestinian Arabs. Among those, in 40 the mutation(s) responsible for the diseases are known. Fourteen of these disorders were caused by a single mutation, while the other 26 were due to multiple mutations. Most of the mutations were found in homozygosity among the affected patients. It is probable that the high frequency of most of the genetic diseases among the Palestinian Arabs is due to a founder effect as the result of the high consanguinity rates in this population. However, in some cases the high frequency was demonstrated to be secondary to the presence of multiple mutations, either allelic or in different genes in a small geographic region. This phenomenon remains unexplained but may be secondary to a selective advantage to the carriers, either specific to the region or to the population., (Copyright 2002 Wiley-Liss, Inc.)

Purpose: Niemann-Pick disease type C (NP-C) is an autosomal recessive lipid storage disease manifested by an impairment in cellular cholesterol homeostasis. The clinical phenotype of NP-C is extremely variable, ranging from an acute neonatal form to an adult late-onset presentation. To facilitate phenotype-genotype studies, we have analyzed multiple Israeli NP-C families., Methods: The severity of the disease was assessed by the age at onset, hepatic involvement, neurological deterioration, and cholesterol esterification studies. Screening of the entire NPC1 coding sequence allowed for molecular characterization and identification of disease causing mutations., Results: A total of nine NP-C index cases with mainly neurovisceral involvement were characterized. We demonstrated a possible link between the severity of the clinical phenotype and the cholesterol esterification levels in fibroblast cultures following 24 hours of in vitro cholesterol loading. In addition, we identified eight novel mutations in the NPC1 gene., Conclusions: Our results further support the clinical and allelic heterogeneity of NP-C and point to possible association between the clinical and the biochemical phenotype in distinct affected Israeli families.

Autosomal recessive diseases are common in the Arab population of Israel, mostly as a result of the high rate of consanguinity. They represent a major factor in the mortality and morbidity of the population. Since the distribution of genetic disorders in this population is not uniform, the present study was performed to determine the frequency and impact of recessive disorders within a single village. We demonstrate the existence of at least 19 autosomal recessive disorders in a village of about 8,600 inhabitants chosen at random. Since most of the disorders were chronic, the prevalence of recessive conditions in the village at the time of the study was at least 1/70, leading to a very high burden to the population and the health services., (Copyright 2000 Wiley-Liss, Inc.)

Since, at least in the near future, prenatal testing and abortion of affected fetuses will remain the main way of the prevention of genetic diseases, knowledge about the way of its acceptance in different cultures is important. The Israeli population includes two major groups: Jewish and Arabs, but while there is wide experience about the Jewish population and its attitude towards prenatal testing, little is known about the Arab population. This knowledge is particularly important, since genetic disorders are relatively frequent in the Arab world (Teebi and Farag, 1997). From 1992 to 1996, 816 prenatal tests were performed in our department on Arab women [143 chorionic villus sampling (CVS) procedures and 673 amniocenteses]. The indication for an early prenatal test was a high risk for a monogenic disorder in 140 out of the 146 tests performed (143 CVS procedures and three early amniocenteses). In 26 cases, the fetus was found to be affected and early abortion was chosen by the couple in 25 cases (96 per cent). The 670 late prenatal tests were done for various reasons including monogenic disorders (13 per cent), increased risk because of a previous child affected with Down syndrome or a neural tube defect (4.8 per cent), and an increased risk for a chromosomal aberration (78 per cent). In 31 cases of a late prenatal test, the fetus was found to be affected and only 21 couples (70 per cent) opted for an abortion. The major reason for this observation is probably related to religious and cultural factors. Since Arab women do not wish to have prenatal testing for only knowledge or reassurance, these factors should be taken into consideration during pre-amniocentesis counselling.

Aspartylglucosaminuria (AGU) is a rare disorder of glycoprotein metabolism caused by the deficiency of the lysosomal enzyme aspartylglucosaminidase (AGA). AGU is inherited as an autosomal recessive trait and occurs with a high frequency in Finland because of a founder effect. While very few patients with AGU have been reported from non-Finnish origin, we diagnosed the disorder in 8 patients originating from 3 unrelated families, all Palestinian Arabs from the region of Jerusalem. The clinical diagnosis of AGU is often difficult, in particular early in the course of the disease, and most of the patients are diagnosed after the age of 5 years. However, since these patients excrete early large amounts of aspartylglucosamine in urine, biochemical screening is easy by urine chromatography.

As a consequence of the high consanguinity rate among the Palestinian Arabs, many recessive disorders are present with a relatively high frequency. In a survey of 2000 different Palestinian Arab families who visited our genetic clinic, in 601 an autosomal recessive disease was diagnosed or strongly suspected. The distribution of these disorders was not uniform and some disorders, such as Krabbe disease, were found at high frequency in only a small part of the population. For some other disorders, a high prevalence was also reported among Palestinian Arabs living in other regions, for example, beta thalassaemia, Bardet-Biedl syndrome, Meckel syndrome, autosomal recessive congenital hydrocephalus, and recessive osteopetrosis. In addition, as another consequence of the high consanguinity rate, two different autosomal recessive diseases were diagnosed within the same sibship in 17 of the Palestinian Arab families.

Congenital hydrocephalus and/or open neural tube defect was present in at least one individual of 98 families out of the 2,000 Palestinian Arabic families who have visited the Genetic clinic at the Hadassah Medical Center. In 22 families the brain malformation was part of a syndrome: Meckel syndrome in 10, Warburg syndrome in another 5, Carpenter in one, and undiagnosed in 6 families. In 76 of the families the neural tube defect and/or the hydrocephalus were non-syndromal. It seems that most of the cases of isolated non-syndromal hydrocephalus represented autosomal recessive traits and that an abnormal allele is common among Palestinian Muslim Arabs.

Among Palestinian Arabs the rate of consanguinity is very high and some 44.3% of the marriages are between relatives (22.6% of them between first cousins). In almost 2,000 files from Palestinian Arab families who attended the genetics clinic in the Hadassah Medical Center; we were able to study the effects of consanguinity on different disorders. The consanguinity rate in families with dominant or X-linked disorders and chromosome aberrations was similar to the one observed in the general population. We did not find any significant differences in the rate of consanguineous marriages between the parents and grandparents of children affected with trisomy 21 and the general population. Thus, we were not able to confirm the suggestion that there is an increase risk for trisomies in children/grandchildren of consanguineous parents. Among the parents of patients with rare autosomal recessive disorders the consanguinity rate was much higher than the one of the general population (92.5%). Among the autosomal recessive disorders, which were relatively frequent in the population, there were fewer marriages between relatives; but in most cases the difference from rare disorders is relatively small. The importance of genetic factors in various congenital malformations, such as neural tube defects and cleft lip/palate or in various forms of infertility, was confirmed by the observation of a significantly higher consanguinity rate in the parents of these patients than is observed in the general population.

Infantile Krabbe disease is a severe, fatal autosomal recessive disorder resulting from the deficiency of galactocerebrosidase (GALC) activity. It is relatively common in two separate inbred communities in Israel. In the Druze community in Northern Israel and two Moslem Arab villages located near Jerusalem the incidence of Krabbe disease is about 1 in 100-150 live births. With our cloning of the GALC gene, mutation analysis of these populations was undertaken. The Moslem Arabs were homozygous for two mutations in the GALC gene; a T-to-C transition at CDNA position 1637 (counting from the A of the initiation codon), which is considered a polymorphism and a G-to-A transition at position 1582, which changes the codon for aspartic acid to one for asparagine. The Druze patients are homozygous for a T-to-G transversion at position 1748, which changes the codon for isoleucine to one for serine. Expression studies confirmed the deleterious nature of these mutations. The development of a simple polymerase chain reaction (PCR) amplification and restriction enzyme digestion method to identify these alleles will lead to accurate carrier testing and improved genetic counseling for interested individuals in these communities.

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.

Metachromatic leukodystrophy is a lysosomal storage disorder caused by the deficiency of arylsulfatase A. The disease occurs panethnically, with an estimated frequency of 1/40,000. Metachromatic leukodystrophy was found to be more frequent among Arabs living in two restricted areas in Israel. Ten families with affected children have been found, three in the Jerusalem region and seven in a small area in lower Galilee. Whereas all patients from the Jerusalem region are homozygous for a frequent mutant arylsulfatase A allele, five different mutations were found in the families from lower Galilee. In patients of Muslim Arab origin, we have found a G86-->D, a S96-->L, and a Q190-->H substitution. Two different defective arylsulfatase A alleles, characterized by a T274-->M and a R370-->W substitution, respectively, have been found among the Christian Arab patients. All mutations were introduced into the wild-type arylsulfatase A cDNA. No enzyme activity could be expressed from the mutagenized cDNAs after transfection into heterologous cells. In all instances, the patients were found to be homozygous for the mutations, and four of the five mutations occurred on different haplotypes. The clustering of this rare lysosomal storage disease in a small geographic area usually suggests a founder effect, so the finding of five different mutations is surprising.

The state of Israel was founded in 1948 and includes approximately 4.5 million Jews and 1 million of non-Jews, mainly Muslim Arabs. Subgroups can be distinguished within each of these two groups: among the Jews according to their country of origin and among the non-Jews according to their religion or even their village of origin. The precise origin of each patient is particularly important for the medical geneticists since in each subgroup some hereditary disorders have been reported with an increased frequency. This knowledge also allows in some cases for preventive genetic screening. The reasons for the relatively high frequency of mendelian disorders in the different communities in Israel are numerous including mainly a founder effect with genetic drift and selection. In Israel, medical genetics is a recognized medical speciality and there are eleven clinical genetic centers in the country. These centers are in close contact with the individuals active in the different fields of human genetics in Israel both for service and research.

Linkage analysis of 18 neurofibromatosis type I (NFI) families was performed using intragenic and flanking polymorphic markers. The aims of the analysis were prenatal diagnosis of at-risk fetuses, and of asymptomatic individuals who were relatives of NFI patients. Prenatal diagnosis was performed in 9 pregnancies of 7 families; 5 fetuses were diagnosed as affected. In 6 families with an affected spouse, the request was to identify informative polymorphisms to be used in future pregnancies. Presymptomatic diagnosis was performed in 4 families. One individual, a brother of an NFI patient, was found to have Lisch nodules as the only NFI symptom. Linkage analysis indicated that if this person is a carrier of the NFI gene, he must be a product of intragenic crossover. In 2 individuals with a new NFI mutation, the origin of the NFI-bearing chromosomes was paternal. The same observation was noted by others. A summary of published cases shows that some 90% of the NFI-bearing chromosomes of patients with new mutations were of paternal origin. We therefore suggest that for the purpose of prenatal diagnosis in carriers of NFI new (and unidentified) mutations, the paternal chromosome will be considered as the NFI-bearing chromosome.

The allele for pseudodeficiency (PD) of the lysosomal enzyme arylsulfatase A (ARSA) is a common polymorphism in all populations. The PD allele frequency in different Israeli ethnic groups was found to range from 9.2-22.7%. The PD allele includes two different mutations PD(1) and PD(2) in an approximately 1 Kb interval. In this study we confirmed that while PD(1) may be found alone as a polymorphism, PD(2) is always associated with the PD allele (660 alleles screened). Analysis of three ARSA intragenic polymorphisms showed a complete linkage disequilibrium between the PD allele and an haplotype defined by the three polymorphic restriction sites. The results suggest that the origin of the PD polymorphism may be a common founder, or recurrent mutations which are occurring in a unique haplotype.

Colobomatous microphthalmia was studied in multiple relatives of 5 families. In these families, the disorder was an autosomal recessive trait as opposed to the usual autosomal dominant form of the disorder. A relatively high incidence of this recessive allele is found in the Iranian Jewish community.