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Thursday, August 9, 2012

Genetic disorder within different religious and ethnic communities

Most genetic disorder are autosomal recessive, they can be hidden in the genome without causing any severe health problems for generations. Examples are Sickle cell anemia, Cystic fibrosis, Lysosomal acid lipase deficiency, Tay-Sachs disease, Phenylketonuria, Mucopolysaccharidoses, Glycogen storage diseases, Galactosemia.

Two mutated SNPs of the same allele are needed to get the symptoms of these disorders; one is inherited from the mother and one from the father who both act as carriers.

The chance of such an unfortunate coincidence increases if the parents are closely related or if both belong to a relatively small community that practices endogamy and is based on a small founder population. The chance of a genetic disorder can be roughly estimated by the average length of shared DNA segments (IBD=Identical by descent) within a community. 

Recently, Dienekes analyzed a few populations and determined the IBD length within the community (and between different communities, not shown here).

IBD score in cM (centiMorgan):

151    Iraq_Jews
129.3    Druze
115.8    Yemen_Jews
110.5    Bedouin
106.4    Morocco_Jews
106.2    Ashkenazi_D
99.8    Ashkenazy_Jews
91.7    Chechens_Y
91.1    Palestinian
81.3    Lithuanians
79.7    Saudis
72.2    Yemenese
70.2    North_Ossetians_Y
67.4    Moroccans
61.9    Russian
51.9    Adygei
51.2    Lezgins
50    Assyrian_D
49.3    Balkars_Y
46.3    Abhkasians_Y
44    Polish_D
42.9    Georgians
42.6    Ukranians_Y
30.3    North_African_Jews_D
28.9    Sephardic_Jews
27    German_D
26.6    Cypriots
26.5    North_Italian
25.3    Kumyks_Y
24.3    Hungarians_19
22.9    Romanians_14
22.4    French
21.7    Jordanians
21.1    Portuguese_D
20.9    Spaniards
20.9    Bulgarians_Y
20.6    Kurd_D
17    TSI30
15.6    Greek_D
12.5    Armenians_Y
12.4    C_Italian_D
11.9    Iranians_19
10.8    S_Italian_Sicilian_D
10.3    Sicilian_D
9.9    Turks
9.4    Syrians

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