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Genetic studies on Arabs refers to the analyses of the genetics of ethnic Arab people in the Middle East and North Africa. Arabs are genetically diverse as a result of their intermarriage and mixing with indigenous people of the pre-Islamic Middle East and North Africa following the Arab and Islamic expansion. [1] [2] Genetic ancestry components related to the Arabian Peninsula display an increasing frequency pattern from west to east over North Africa. A similar frequency pattern exist across northeastern Africa with decreasing genetic affinities to groups of the Arabian Peninsula along the Nile river valley across Sudan and the more they go south. [3] This genetic cline of admixture is dated to the time of Arab expansion and immigration to North Africa (Maghreb) and northeast Africa. [3]
In the Levant, the introduction of Islam to the region and the conversion of the region’s population to it caused major rearrangements in populations' relations and affinities through admixture with "culturally similar but geographically remote populations" with whom they enjoyed a shared Islamic culture, Arab culture and Arabic language, which led to "genetic similarities between remarkably distant populations like Jordanians, Moroccans, and Yemenis". [4]
A 2018 study of Arabs found that Peninsular Arabs genetically showed two distinct clusters and that Arabs in general can be genetically stratified into four groups; the first consisting of Maghrebi Arabs (Algerians, Moroccans, Tunisians and Libyans) along with the first Arabian Peninsula cluster, which consists of Saudis, Kuwaitis and Yemenis, the second consisting of Levantine Arabs (Palestinians, Lebanese, Syrians and Jordanians) along with Egyptians and Iraqis, the third compromising Sudanese and Comorians, and the fourth compromising the second Arabian Peninsula cluster consisting of Omanis, Emiratis, and Bahrainis. The study confirmed the high genetic heterogeneity among Arabs, especially those of the Arabian Peninsula. [1]
The most dominant Paternal Y haplogroup in Arab countries is the Arabian haplogroup J1 (J-M267) and especially its main clade J1-P58 reaching up to 80% in some countries such as Yemen, Qatar and Sudan, according to latest samples studies. [5] J1-M267 that is not P58 are found in Yemen and Oman. The mutation STR DYS388 equal or above 16 found in J1-p58 was used as genetic profiling in Forensics since the 80s to determine Middle Eastern ancestry. (Nebel et Al 2001) [6]
Below is the general distribution of Y-DNA haplogroups among populations of the Arab world:
Population | Language Family [7] | n [8] | R1b [9] | n | R1a | n | I | n | E1b1b | n | E1b1a | n | J | n | G | n | N | n | T | n | L |
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Arabs (Algeria) | Afro-Asiatic (Semitic) | 35 | 13.0 [10] | 35 | 0.0 [10] | 32 | 50 [11] | 35 | 35 [10] | ||||||||||||
Arabs (Algeria – Oran) | Afro-Asiatic (Semitic) | 102 | 10.8 [12] | 102 | 1 [12] | 102 | 50.9 [12] | 102 | 12.8 [12] | 102 | 27.4 [12] | ||||||||||
Arabs (Bedouin) | Afro-Asiatic (Semitic) | 32 | 0.0 [13] | 32 | 9.4 [13] | 32 | 6.3 [13] | 32 | 18.7 [13] | 32 | 65.6 [13] | 32 | 0.0 [13] | ||||||||
Arabs (Iraq) | Afro-Asiatic (Semitic) | 10.8 [14] | 6.5 [14] | 218 | 8.3 [11] | 218 | 0.9 [11] | 156 | 50.6 [11] | ||||||||||||
Arabs (Israel) | Afro-Asiatic (Semitic) | 143 | 8.4 [13] | 143 | 1.4 [13] | 143 | 6.3 [13] | 143 | 20.3 [13] | 143 | 55.2 [13] | 143 | 0.0 [13] | ||||||||
Arabs (Morocco) | Afro-Asiatic (Semitic) | 44 | 3.8 [15] | 44 | 0.0 [15] | 44 | 0.0 [15] | 49 | 85.5 [11] | 49 | 20.4 [11] | ||||||||||
Arabs (Oman) | Afro-Asiatic (Semitic) | 121 | 1.7 [16] | 121 | 9.1 [16] | 121 | 0.0 [16] | 121 | 15.7 [16] | 121 | 7.4 [16] | 121 | 47.9 [16] | 121 | 1.7 [16] | 121 | 8.3 [16] | 121 | 0.8 [16] | ||
Arabs (Qatar) | Afro-Asiatic (Semitic) | 72 | 1.4 [17] | 72 | 6.9 [17] | 72 | 0.0 [17] | 72 | 5.6 [17] | 72 | 2.8 [17] | 72 | 66.7 [17] | 72 | 2.8 [17] | 72 | 0.0 [17] | 72 | 0.0 [17] | 72 | 2.8 [17] |
Arabs (Saudi Arabia) | Afro-Asiatic (Semitic) | 157 | 1.9 [18] | 157 | 5.1 [18] | 157 | 0.0 [18] | 157 | 7.6 [18] | 157 | 7.6 [18] | 157 | 58.0 [18] | 157 | 3.2 [18] | 157 | 0.0 [18] | 157 | 5.1 [18] | 157 | 1.9 [18] |
Arabs (UAE) | Afro-Asiatic (Semitic) | 164 | 4.3 [17] | 164 | 7.3 [17] | 164 | 11.6 [17] | 164 | 5.5 [17] | 164 | 45.1 [17] | 164 | 4.3 [17] | 164 | 0.0 [17] | 164 | 4.9 [17] | 164 | 3.0 [17] | ||
Arabs (Yemen) | Afro-Asiatic (Semitic) | 62 | 0.0 [17] | 62 | 0.0 [17] | 62 | 0.0 [17] | 62 | 12.9 [17] | 62 | 3.2 [17] | 62 | 82.3 [17] | 62 | 1.6 [17] | 62 | 0.0 [17] | 62 | 0.0 [17] | 62 | 0.0 [17] |
Arabs (Syria) | Afro-Asiatic (Semitic) | 20 | 15.0 [19] | 20 | 10.0 [19] | 20 | 5.0 [19] | 20 | 10.0 [19] | 20 | 53.0 [19] | 20 | 0.0 [19] | 20 | 0.0 [19] | 20 | 0.0 [19] | 20 | 0.0 [19] | ||
Arabs (Lebanon) | Afro-Asiatic (Semitic) | 31 | 6.4 [19] | 31 | 9.7 [19] | 31 | 3.2 [19] | 31 | 25.8 [19] | 31 | 45.2 [19] | 31 | 3.2 [19] | 31 | 0.0 [19] | 31 | 0.0 [19] | 31 | 3.2 [19] | ||
Arabs (Sudan) | Afro-Asiatic (Semitic) | 102 | 15.7 [20] | 102 | 3.9 [20] | 102 | 16.7 [20] | 102 | 47.1 [20] | ||||||||||||
Arabs (Tunisia) | Afro-Asiatic (Semitic) | 148 | 6.8 [10] | 148 | 0.0 [10] | 148 | 0.0 [10] | 148 | 49.3 [10] | 148 | 1.4 [10] | 148 | 35.8 [10] | 148 | 0.0 [10] | 148 | 0.7 [10] | 148 | 0.0 [10] | ||
Arabs (Libya) | Afro-Asiatic (Semitic) | 63 | 3 [21] | 63 | 1.5 [21] | 63 | 1.5 [21] | 63 | 52.0 [21] | 63 | 0.0 [21] | 63 | 24.0 [21] | 63 | 8.0 [21] | 63 | 5.0 [21] | 63 | 1.5 [21] | ||
Saharawi (SADR) | Afro-Asiatic (Semitic) | 29 | 79.3 [11] | 29 | 3.4 [11] | 29 | 17.2 [11] | ||||||||||||||
Egyptians | Afro-Asiatic (Semitic) | 92-147 | 5.4 [22] -4.1 | 92-147 | 0.0 [22] -2.7 [16] | 92-147 | 1.1 [22] -0.7 [16] | 92-147 | 43.5 [22] -36.7 [16] | 92-147 | 3.3 [22] -2.8 [16] | 92-147 | 22.8 [22] -32.0 [16] | 92-147 | 2.2 [22] -8.8 [16] | 92-147 | 0.0 [22] -0.0 [16] | 92-147 | 7.6 [22] -8.2 [16] | 92 | 0.0 [22] |
Egyptians (North) | Afro-Asiatic (Semitic) | 43 | 9.3 [23] | 43 | 2.3 [23] | 43 | 0.0 [23] | 43 | 53.5 [23] | 44 | 18.2 [10] | 43 | 7.0 [23] | 43 | 2.3 [23] | 43 | 0.0 [23] | ||||
Egyptians (South) | Afro-Asiatic (Semitic) | 47 | 13.8 [24] | 47 | 78.7 [24] | ||||||||||||||||
Lebanese | Afro-Asiatic (Semitic) | 914 | 8.1 [25] | 914 | 2.5 [23] | 914 | 4.8 [23] | 914 | 16.2 [23] | 914 | 0.7 [23] | 914 | 46.1 [23] | 914 | 6.6 [23] | 914 | 0.1 [23] | 914 | 4.7 [23] | 914 | 5.2 [23] |
The maternal ancestral lineages of Arabic countries are diverse. The original and still most prevalent maternal haplogroups of the Near East (Syria, Lebanon, Palestine, Iraq, Arabian Peninsula) and Egypt are mt (maternal) R0a1 (previously called pre-HV), M1 haplogroup ( The "back to Africa " haplogroup) a branch of Asian Haplogroup M (mtDNA) which branched from L3 Haplogroup around 70 000 years ago, and (maternal) HV1 haplogroup a branch of HV1 haplogroup that are still high in Yemen, while in the region of Syria there is a Eurasian maternal gene flow, and U5 haplogroup. [26] [27] [20]
Many of the genetic disorders specific to Arabs are located on HLA segment on chromosome 6. These same segment mutations are also markers of Arabs in genealogical and forensic profiling tests and studies. [28] [29] [26] [27] [20] [30] [31]
There are four principal West-Eurasian autosomal DNA components that characterize the populations of the Arab world, namely: the Arabian, Levantine, Coptic, and Maghrebi components.[ citation needed ] The Arabian component is the main autosomal element in the Gulf region. It is most closely associated with local Arabic-speaking populations. [32]
A genetic study published in the "European Journal of Human Genetics" in Nature (2019) showed that Middle Easterners (Arabs) are closely related to Europeans and Northern Africans as well as to Southwest Asians. [38] The "Arab macropopulation" is generally closely related to other "West-Eurasian" populations, such as Europeans or Iranian peoples. The Arab expansion marked one of the last expansions of West-Eurasian ancestry into Africa, with the earliest scientifically attested West-Eurasian geneflow into Africa being dated back to 23,000 BCE (or already earlier), and may be associated with the spread of Proto-Afroasiatic from the Middle East. [39] [40] Hodgson et al. (2014) found a distinct non-African ancestry component among Northeastern Africans (dubbed "Ethio-Somali"), which split from other West-Eurasian ancestries, most closely to the Arabian ancestry component, about 23,000 years ago, and migrated into Africa pre-agricultural (between 12,000 to 22,000 years ago). This component is suggested to have been present in considerable amounts among the Proto-Afroasiatic-speaking peoples. The authors argue that the Ethio-Somali component and the Maghrebi component descended from a single ancestral lineage, which split from the Arabian lineage and migrated into Africa from the Middle East. In Africa, this West-Eurasian lineage diverged into the Maghrebi component, predominant in Northern Africa, and the Ethio-Somali component, found in significant varying degrees among populations of the Horn of Africa. [41]
In 2021, a study showed no genetic traces of early expansions out-of-Africa in present-day populations in the Near-East, but found Arabians to have elevated Basal Eurasian ancestry that dilutes their Neanderthal ancestry. [42]
The Arab world has one of the highest rates of genetic disorders globally; some 906 pathologies are endemic to the Arab states, including thalassaemia, Tourette's syndrome, Wilson's disease, Charcot-Marie-Tooth disease, mitochondrial encephalomyopathies, and Niemann-Pick disease. [43]
Several organizations maintain genetic databases for each Arabic country, such as Saudi Human Genome Program (SHGP). Even though the KGP, SHGP, QGP, BGP and EGP are revisiting the genetics and genomics of Arab populations’ ancestries, lack of complete coordination between the initiatives is a major limitation on revealing the real disease markers of the Arab population. [44]
The Centre for Arab Genomic Studies (CAGS) is the main organization based in the United Arab Emirates. It initiated a pilot project to construct the Catalogue for Transmission Genetics in Arabs (CTGA) database for genetic disorders in Arab populations. At present, the CTGA database is centrally maintained in Dubai and hosts entries for nearly 1,540 Mendelian disorders and related genes. This number is increasing as researchers are joining the largest Arab scientific effort to define genetic disorders described in the region. The Center promotes research studies on these emergent disorders. [45]
Some of the genetic disorders endemic to the Arab world are: hemoglobinopathy, sickle cell anemia, glucose-6-phosphate dehydrogenase deficiency, and fragile X syndrome (FXS), which is an inherited genetic condition with critical consequences. The Centre provide information about specific countries, [46] and maintain a list of Genomic diseases. [47] [48] [49]
Specific rare autosomal recessive diseases are high in Arabic countries like Bardet Biedl syndrome, Meckel syndrome, congenital chloride diarrhea, severe childhood autosomal recessive muscular dystrophy (SMARMD), lysosomal storage diseases and PKU are high in the Gulf states. Dr Teebi's book provides detailed information and by country. [50] Even the Middle East respiratory syndrome coronavirus (MERS-CoV) that was first identified in Saudi Arabia last year, it has infected 77 people, mostly in the Middle East and Europe. Forty of them – more than half – have died. But MERS is not yet a pandemic, could become pervasive in genetic disease patient. [51]
Dr Thurman' guidebook about rare genetic diseases [52] Another book Arabic genetic disorders layman guide [53] Saudi Journal article about genetic diseases in Arabic countries [54] The highest proportion of genetic disorders manifestations are: congenital malformations, followed by endocrine metabolic disorders and then by neuron disorders (such as neuromotor disease) and then by blood, immune disorders and then neoplasms. The Mode of Inheritance is mainly autosomal recessive followed by autosomal dominant.
Some of the diseases are beta-thalassemia mutations, sickle-cell disease, congenital heart-disease, glucose-6-phosphate dehydrogenase deficiency, alpha-thalassemia, molecular characterization, recessive osteoperosis, gluthanione-reducatsafe DEf. A study about sickle cell anemia in Arabs [55] article about Birth defects [26] Glucose phosphate isomerase deficiency responsible for unexpected hemolytic episodes. [56] one of late Dr Teebi's syndromes. [57] flash cards guide. [58] [59] [60] [61] NY Times article [62] In Palestinian Arabs study [63] study about potential on pharmacology [64] another study on Arab Palestinians [65] Database of Genetic disorders in Arabs study [66] In Palestinians [67] new general study about databases [68] Database for B thalassemia in Arabs [69] Israeli National genetic bank contains genetic mutations of Arabs [70] Teebi database 2002 [71] 2010 genes responsible for genetic diseases among Palestinian Arabs [72] [73] The next Pan-Arab conference Nov 2013 [74]
Diagnosis of genetic disorders after birth is done by clinicians, lab tests, and sometimes genetic testing. Genetic testing profiling screening of pregnant women's fetuses for List of disorders included in newborn screening programs using microchip genetic microarry might help detect genetic mutations incompatible with life and determining abortion. Some genetic tests of born children might help finding the right treatment. [75] [76] Mothers could test for genetic disorders in the fetus by method of chorionic villus sampling (CVS) or amniocentesis.
It is possible for medical genetic testing to discover genetic mutations that predispose or active in causing a disease that might probably happen in the future at later age or causing a disease with unnoticed symptoms that will increase in the future. genetic testing is increasingly being used by physicians after becoming cheaper, and the still existing resistance by HMO medical providers, because such testing make shortcuts towards faster diagnosis, causing the HMOs to loose profits from extended physicians visits and other laboratory tests that laboratories share profits with HMOs, where "Doctor patient relationship" aimed at helping patient conflict with Profit making HMOs and big clinics.
Consanguinity (interbreeding, marriage between cousins, inside the family, the clan, the tribe, or even country especially small countries like Kuwait, to preserve fortunes in the family or clan or tribe especially after the Oil discovery in Gulf) is the main cause of Arabic genetical diseases, in addition to mutagens such as environmental factors such as the oil industry and radiological waste dumps in sea and land.
Most affected are the small countries such as Kuwait Jordan and the Gulf states, but all other Arabic countries because of Consanguinity. Consanguinity also is causing novel new diseases that are unpredictable and costly to diagnose and treat ( where treatments of genetic diseases are still lacking), characterized by a high level of genetic mutations.
Intellectual disability, neurogenetic disorders, blood and bleeding disorders and rare genetic diseases and retinal dystrophy and novel candidate disease marker variations.while Saudi mtDNA association with obesity.
Intellectual disability comes first with the combined and observed carrier frequency of 0.06779!, followed by retinal dystrophy, glaucoma, inborn errors of metabolism, sickle cell disease/thalassemia, deafness, dysmorphic/dysplasia, ataxia, myopathy/muscular dystrophy, polycystic kidney disease/nephronophthisis, Joubert syndrome/Meckel-Gruber syndrome, carbonic anhydrase II deficiency, cystic fibrosis, Bardet-Biedl syndrome, and cataract.
Carrier frequency of the intellectual disability is three times more than that of sickle cell disease and thalassemia among the Arab population with 25–60% consanguinity rates!. 33 genes (observed phenotype), were identified among the pre-screened multiplex consanguineous families with neurogenetic disorders.
Previously known Blood and bleeding disorders: Molecular defects, blood disorders, β-thalassemia, sickle cell disorder, α-thalassemia and G6PD (glucose-6-phosphate dehydrogenase) deficiency are the most common in the Arab population.
Since Arabic populations tend to have Arabic paternal ancestry, mainly the Arabian male Y- J1 haplogroup especially j1-P58 There is much more of a diversity amongst the maternal ancestries gene pool, but "historically" poor countries such as Yemen and Arabian peninsula lack female ancestry diversity, as seen most in greater Syria Iraq and Egypt that have extra maternal haplogroups than the Middle East- associated maternal (aka mito or mitochondrial) HV1b, U, U5, M1, R0a haplogroups, and the traditional Consanguinity that had increased due to oil fortune preservation trend, significantly trumped up the genetic diseases and genetic predisposition for such diseases that are becoming Novel "new" in nature, ie unknown yet to discover and understand the etiology and prepare treatments or prevention.
The new trend to stay local among Arabic populations in Arabic countries and especially after creating small countries after independence from the west in the 50s.Marrying into a different gene pool such as historically isolated Yemen or different and isolated ie Indonesia would help.
While diabetes is very prevalent among Arabs 10% up to 20%, responsible Arab genes have not been found yet but Saudi mitochondrial gene was found that cause obesity that predispose to diabetes. [44] [77]
Bare lymphocyte syndrome high in western Arabic block Morocco, type II limb-girdle muscular dystrophy, type 2C in Libya, hemolytic-uremic syndrome in Saudia, ankylosing spondylitis in Egypt and East block, alpha-thalassemia in all countries except Egypt, Syria, and Iraq, cystic fibrosis in Iraq Saudi Yemen Libya Morocco, familial Mediterranean fever fmf in east block and Libya Morocco, beta thalassemia in all countries, g6dh deficiency all countries. [59]
Most genetic markers of Arabs' genetic diseases are phenotypic, i.e. specific mutations of Arab peoples, especially in countries. Even though genetic mutations of Gulf states are mostly the same, but some genetic phenotypes are Kuwaiti etc.
The diseases have geographical distribution among Arab countries such as greater Syria, Gulf states, Yemen, Western block (Morocco, Algeria, Tunisia), because of the restricted marriages to each block or even to one country. Moreover, cousin marriages (consanguinity) and endogamy (marriages restricted to minority sects) exacerbate the problem. Distancing of marriages from distant gene pools might help resolve the problem in Arabic countries. Many of the pronounced genetic deficiencies in Arabs are located on HLA segment on chromosome 6. This same segment mutations are markers of Arabs in Genealogical and forensic profiling tests and studies. Such studies as: [26] [30] [27] [20] [31] Arab population data on the PCR-based loci:HLA [28] HLA polymorphism in Saudi. [29]
Since over 70% of Arab genetic disorders are autosomal-recessive, meaning the defective gene has to be found in both father and mother, and since the gene pool is similar in population (males and females alike since autosomal chromosomes are admixture from father and mother, in closed societies (marriages from same sect endogamy, or same tribe or even from same country, or even from the same block of countries since it is similar in geographical blocks as shown in the online brochures referenced above. [78]
Preface: The founder effect disease causing mutations where "The founder effect refers to the concept that a given gene appeared (presumably by mutation) in a small ancestral population (i.e., in a founder) and by random chance was transmitted to a large number of that founder’s offspring.". The founder population could be the common ancestry of Arabs or the forced localizations caused by artificial countries inside the larger group of ancestry, hence causing Arab specific founder effect mutation disease found only in all Arabic countries, and Arabic country specific mutation diseases caused by increasing Homozygosity ( the existence of same gene on both chromosomes pairs, hence recessive disease increasing in just few generations). The genetic abnormality will increase incrementally with the decrease of number of isolated populations making tribe specific diseases and new Novel genetic defects. [79]
In recessive diseases, founder populations where underlying levels of genome-wide homozygosity are high due to shared common ancestry, but also for consanguineous populations that will have large genome-wide homozygous regions due to inbreeding. Having a catalog of disease-associated variation in these populations enables rapid, early, and accurate diagnoses that may improve patient outcomes due to informed clinical management and early interventions. [80]
The following are diseases that can happen to genetic mutations that have ancient ancestry founding effect mutations that happened in Arabic Ancestry ( not including the many Novel new mutations caused by Consanguinity and unknown factors in recent times): [81]
To use Genetic counseling especially before and after marriage, avoiding Consanguinity, marrying into a different gene pool especially that did not have Consanguinity. Avoiding mutagens ie factors that cause mutations such as radioactive and other environmental factors such as living near high microwave frequency electric poles, and near or on top of previous "Brown Fields" AKA industrial establishment. The importance to report to the medical provider the ethnicity As Arabic or Berber and specific country such as Saudi Arabia so the provider can design genetic testing and other tests to discover the possible ailments especially large DNA sequencing and specific DNA testing became available and reasonably affordable. Most genetic diseases go unnoticed by person or physician or dormant and show up later in life, and so genetic testing might reveal the probable existence or dormancy of a disease or syndrome before it manifest or to confirm a disease in spite of negative other non genetic laboratory tests. many disease causing genetic alterations are country specific or even sub category such as " Jewish Tunisian" for example. knowing the ancestral Y paternal and mitochondrial maternal haplogroups and other private companies Nuclear DNA might give Bird's eye view of what to expect along with self identification of race and country of origin. Interventions during pregnancy, including: early detection and management of maternal conditions such as diabetes; early detection and management of infections. avoidance of teratogens (infections such as toxoplasmosis, drugs); prenatal screening by maternal serum markers in first trimester and by ultrasonography; prenatal diagnosis with/without termination of pregnancy; care of fetus for conditions such as Rh incompatibility; avoidance of tobacco use and exposure to pollution; and supplementation with iron and folate. Interventions after birth, including: newborn biochemical screening for congenital hypothyroidism, phenylketonuria (PKU), galactosaemia, sickle cell disorder, glucose-6-phosphate dehydrogenase (G6PD) deficiency, congenital adrenal hyperplasia, methyl coenzyme dehydrogenase deficiency;. [82]
Teebi type of hypertelorism (1987), Teebi Shaltout syndrome (1989), Al Gazali syndrome (1994), Megarbane syndrome (2001)
There are even new Arabic names for emerging genetic disorders and syndromes like:
Spectrum of Genetic Disorders in Arabs, Lebanese type of mannose 6--phosphate receptor recognition defect (1984), Algerian type of spondylometaphyseal dysplasia (1988), Kuwaiti type of cardioskeletalsyndrome (1990), Yemenite deaf-blind hypopigmentation syndrome (1990), Nablus mask-like facial syndrome (2000), Jerash type of the distal hereditary motor neuropathy (2000), Karak syndrome (2003), Omani type of spondyloepiphy. [83]
An autosome is any chromosome that is not a sex chromosome. The members of an autosome pair in a diploid cell have the same morphology, unlike those in allosomal pairs, which may have different structures. The DNA in autosomes is collectively known as atDNA or auDNA.
A genetic disorder is a health problem caused by one or more abnormalities in the genome. It can be caused by a mutation in a single gene (monogenic) or multiple genes (polygenic) or by a chromosome abnormality. Although polygenic disorders are the most common, the term is mostly used when discussing disorders with a single genetic cause, either in a gene or chromosome. The mutation responsible can occur spontaneously before embryonic development, or it can be inherited from two parents who are carriers of a faulty gene or from a parent with the disorder. When the genetic disorder is inherited from one or both parents, it is also classified as a hereditary disease. Some disorders are caused by a mutation on the X chromosome and have X-linked inheritance. Very few disorders are inherited on the Y chromosome or mitochondrial DNA.
Joubert syndrome is a rare autosomal recessive genetic disorder that affects the cerebellum, an area of the brain that controls balance and coordination.
Bloom syndrome is a rare autosomal recessive genetic disorder characterized by short stature, predisposition to the development of cancer, and genomic instability. BS is caused by mutations in the BLM gene which is a member of the RecQ DNA helicase family. Mutations in genes encoding other members of this family, namely WRN and RECQL4, are associated with the clinical entities Werner syndrome and Rothmund–Thomson syndrome, respectively. More broadly, Bloom syndrome is a member of a class of clinical entities that are characterized by chromosomal instability, genomic instability, or both and by cancer predisposition.
Sex linked describes the sex-specific reading patterns of inheritance and presentation when a gene mutation (allele) is present on a sex chromosome (allosome) rather than a non-sex chromosome (autosome). In humans, these are termed X-linked recessive, X-linked dominant and Y-linked. The inheritance and presentation of all three differ depending on the sex of both the parent and the child. This makes them characteristically different from autosomal dominance and recessiveness.
Human genetics is the study of inheritance as it occurs in human beings. Human genetics encompasses a variety of overlapping fields including: classical genetics, cytogenetics, molecular genetics, biochemical genetics, genomics, population genetics, developmental genetics, clinical genetics, and genetic counseling.
Haploinsufficiency in genetics describes a model of dominant gene action in diploid organisms, in which a single copy of the wild-type allele at a locus in heterozygous combination with a variant allele is insufficient to produce the wild-type phenotype. Haploinsufficiency may arise from a de novo or inherited loss-of-function mutation in the variant allele, such that it yields little or no gene product. Although the other, standard allele still produces the standard amount of product, the total product is insufficient to produce the standard phenotype. This heterozygous genotype may result in a non- or sub-standard, deleterious, and (or) disease phenotype. Haploinsufficiency is the standard explanation for dominant deleterious alleles.
Carnitine palmitoyltransferase I deficiency is a rare metabolic disorder that prevents the body from converting certain fats called long-chain fatty acids(LCFA) into energy, particularly during periods without food. It is caused by a mutation in CPT1A on chromosome 11.
Severe congenital neutropenia (SCN), also often known as Kostmann syndrome or disease, is a group of rare disorders that affect myelopoiesis, causing a congenital form of neutropenia, usually without other physical malformations. SCN manifests in infancy with life-threatening bacterial infections. It causes severe pyogenic infections. It can be caused by autosomal dominant inheritance of the ELANE gene, autosomal recessive inheritance of the HAX1 gene. There is an increased risk of leukemia and myelodysplastic cancers.
Short-chain acyl-coenzyme A dehydrogenase deficiency (SCADD) is an autosomal recessive fatty acid oxidation disorder which affects enzymes required to break down a certain group of fats called short chain fatty acids.
Laurence–Moon syndrome (LMS) is a rare autosomal recessive genetic disorder associated with retinitis pigmentosa, spastic paraplegia, and mental disabilities.
Gray platelet syndrome (GPS), or platelet alpha-granule deficiency, is a rare congenital autosomal recessive bleeding disorder caused by a reduction or absence of alpha-granules in blood platelets, and the release of proteins normally contained in these granules into the marrow, causing myelofibrosis. The name derives from the initial observation of gray appearance of platelets with a paucity of granules on blood films from a patient with a lifelong bleeding disorder.
In medical genetics, compound heterozygosity is the condition of having two or more heterogeneous recessive alleles at a particular locus that can cause genetic disease in a heterozygous state; that is, an organism is a compound heterozygote when it has two recessive alleles for the same gene, but with those two alleles being different from each other. Compound heterozygosity reflects the diversity of the mutation base for many autosomal recessive genetic disorders; mutations in most disease-causing genes have arisen many times. This means that many cases of disease arise in individuals who have two unrelated alleles, who technically are heterozygotes, but both the alleles are defective.
The medical genetics of Jews have been studied to identify and prevent some rare genetic diseases that, while still rare, are more common than average among people of Jewish descent. There are several autosomal recessive genetic disorders that are more common than average in ethnically Jewish populations, particularly Ashkenazi Jews, because of relatively recent population bottlenecks and because of consanguineous marriage. These two phenomena reduce genetic diversity and raise the chance that two parents will carry a mutation in the same gene and pass on both mutations to a child.
Lethal congenital contracture syndrome 1 (LCCS1), also called Multiple contracture syndrome, Finnish type, is an autosomal recessive genetic disorder characterized by total immobility of a fetus, detectable at around the 13th week of pregnancy. LCCS1 invariably leads to prenatal death before the 32nd gestational week. LCCS1 is one of 40 Finnish heritage diseases. It was first described in 1985 and since then, approximately 70 cases have been diagnosed.
The genetic history of the African diaspora is composed of the overall genetic history of the African diaspora, within regions outside of Africa, such as North America, Central America, the Caribbean, South America, Europe, Asia, and Australia; this includes the genetic histories of African Americans, Afro-Canadians, Afro-Caribbeans, Afro-Latinos, Afro-Europeans, Afro-Asians, and African Australians.
Otofaciocervical syndrome, also known as Fara Chlupackova syndrome, are a small group of rare developmental disorders of genetic origin which are characterized by facial dysmorphisms, long neck, preauricular and/or branchial pits, cervical muscle hypoplasia, hearing loss, and mild intellectual disabilities. Additional findings include vertebral anomalies and short stature.
Salt and pepper developmental regression syndrome, also known as Amish infantile epileptic syndrome or GM3 deficiency syndrome, is a rare autosomal recessive progressive neurological disorder characterized by developmental delay, severe intellectual disability, seizures, and skin pigmentation irregularities. The clinical symptoms of this condition start manifesting soon after birth, during the newborn/neo-natal stage of life.
SOFT syndrome, also known for the name its acronym originates from: Short stature-onychodysplasia-facial dysmorphism-hypotrichosis syndrome, is a rare genetic disorder characterized by the presence of short stature, underdeveloped nails, facial dysmorphisms, and hair sparcity across the body. It is caused by homozygous, autosomal recessive mutations in the POC1A gene, located in the short arm of chromosome 3. Fewer than 15 cases have been described in the medical literature.
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: CS1 maint: bot: original URL status unknown (link)Affected individuals are born with ambiguity of the external genitalia and reared as females until puberty, found in Palestinians