Because of centuries of
endogamy, today's ten million Ashkenazi Jews descend from a population of 350 who lived about 600–800 years ago. That population derived from both Europe and the Middle East. Some evidence shows that the
population bottleneck may have allowed deleterious
alleles to increase in the population by
genetic drift. This group has therefore been particularly intensively studied, and many mutations are common in Ashkenazim. Of these diseases, many also occur in other Jewish groups and non-Jewish populations, although the specific mutation that causes the disease may vary among populations. For example, two mutations in the
glucocerebrosidase gene each cause
Gaucher's disease in Ashkenazim, which is that group's most common genetic disease, but only one of these mutations is found in non-Jewish groups. with lower levels of the disease in some Pennsylvania Dutch, Italian, Irish Catholic, and French Canadian descent, especially those living in the Cajun community of Louisiana and the southeastern Quebec. Since the 1970s, however, proactive genetic testing has been quite effective in eliminating Tay–Sachs from the Ashkenazi Jewish population. The first mass Tay-Sachs screening program for Ashkenazi Jews occurred in May of 1971 at Congregation Beth El, a Conservative Shul in Bethesda, Maryland.
Lipid transport diseases of
Gaucher disease, with cells that have the characteristic crumpled
tissue paper-like
cytoplasm.
H&E stain.
Gaucher's disease, in which
lipids accumulate in inappropriate locations, occurs most frequently among Ashkenazi Jews; the mutation is carried by roughly one in every 15 Ashkenazi Jews, compared to one in 100 of the general American population. Gaucher's disease can cause
brain damage and
seizures, but these effects are not usually present in the form manifested among Ashkenazi Jews; while those affected still bruise easily, and it can still potentially rupture the
spleen, it generally has only a minor impact on life expectancy. Ashkenazi Jews are also highly affected by other
lysosomal storage diseases, particularly in the form of
lipid storage disorders. Compared to other ethnic groups, they more frequently act as carriers of
mucolipidosis and
Niemann–Pick disease, the latter of which can prove fatal. The occurrence of several lysosomal storage disorders in the same population suggests the alleles responsible might have conferred some
selective advantage in the past. This would be similar to the
hemoglobin allele which is responsible for
sickle-cell disease, but solely in people with two copies; those with just one copy of the allele have a
sickle cell trait and gain partial immunity to
malaria as a result. This effect is called
heterozygote advantage.
Familial dysautonomia Familial dysautonomia (Riley–Day syndrome), which causes
vomiting, speech problems, an inability to
cry, and false
sensory perception, is almost exclusive to Ashkenazi Jews; Ashkenazi Jews are almost 100 times more likely to carry the disease than anyone else.
Other Ashkenazi diseases and disorders Diseases inherited in an
autosomal recessive pattern often occur in
endogamous populations. Among Ashkenazi Jews, a higher incidence of specific
genetic disorders and
hereditary diseases has been verified, including: •
Alport syndrome •
Colorectal cancer due to
hereditary nonpolyposis colorectal cancer •
Congenital adrenal hyperplasia (nonclassical form) •
Congenital insensitivity to pain with anhidrosis •
Crohn's disease (the
NOD2/CARD15 locus appears to be implicated) •
Joubert syndrome type 2 is disproportionately frequent among people of Jewish descent; this has been attributed to the resistance to intermarriage of this population. •
Kaposi's sarcoma •
Maple syrup urine disease •
Mucolipidosis IV •
Myeloproliferative neoplasms including
polycythemia vera and
essential thrombocythemia •
Nonsyndromic hearing loss and deafness,
DFNB1 (
connexin 26) •
Parkinson's disease (
G2019S/
LRRK2 mutation; The
LRRK2 mutation on the main haplotype, shared by Ashkenazi Jews, North Africans, and Europeans, initially arose in the Near East at least 4000 years ago. Because of a founder effect, the ancestors of present-day Ashkenazi Jews may have kept the low-frequency
G2019S mutation through the different diasporas, whereas Near Eastern daughter populations lost the mutation. The mutation might then have been "reintroduced by recurrent gene flow from Ashkenazi populations to other Jewish, European, and North African populations. The present-day frequency of the mutation in control populations (0.05% in Europeans, 0.5% in North-African Arabs and 1% in Ashkenazi Jews) may support this scenario".) •
Pemphigus vulgaris •
Schizophrenia (
NDST3 gene variation) •
Von Gierke disease •
Zellweger syndrome ==Sephardi and Mizrahi diseases==