Schizophrenia

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WHO-ICD-10 version:2010

Mental and behavioural disorders

Schizophrenia, schizotypal and delusional disorders

OMIM Number

181500

Mode of Inheritance

Autosomal dominant

Gene Map Locus

1p36.2, 1q42.2 ,5q23-q35 ,6p23, 6q13-q26,8p21 ,10q22.3,11q14-q21 ,13q32, 13q33.2, ,18p ,22q12.3

Description

Schizophrenia is a chronic, severe, and disabling brain disorder, clinically manifesting in acute episodes associated with hallucinations, delusions, and disordered thinking and behavior. Signs and symptoms of schizophrenia are divided into three categories: positive symptoms that include psychotic symptoms, negative symptoms that include a decrease in emotional range, poverty of speech, and loss of interests and drive, and cognitive symptoms that include neurocognitive deficits. Schizophrenia affects approximately 0.7% of world populations.

Diagnosis of schizophrenia is based on evaluation by a psychiatrist, tests, and medical history. Schizophrenia requires lifelong treatment with a focus on eliminating the symptoms of the disease, and include antipsychotic medications and various psychosocial treatments.

The cause of schizophrenia is still unknown, but researchers believe that a combination of genetics and environment contributes to development of the disease. Studies show that schizophrenia has a heritability of about 80%. However, it is difficult to relate gene changes to discrete physiological or biochemical changes associated with the disease. The most implicated genes in schizophrenia are those involved in dopamine or glutamate signaling, the two signaling systems. Single nucleotide polymorphisms (SNPs) in the CHL1 gene have been linked to schizophrenia in some populations.

Epidemiology in the Arab World

View Map
Subject IDCountrySexFamily HistoryParental ConsanguinityHPO TermsVariantZygosityMode of InheritanceReferenceRemarks
181500.G.1United Arab Emirates SchizophreniaNM_006457.5:c.*1006A>G, NM_006457.5:c.*1054delAutosomal, DominantMoselhy et al. 2015 121 patients (71 mal...

Other Reports

Qatar

Shaltout et al. (2013) investigated the association between the close homologue of L1 (CHL1) polymorphisms and Schizophrenia in 86 Qatari schizophrenic patients and 88 healthy unrelated Qataris. A significant association was found between the rs2272522 SNP and schizophrenic patients. Patients with the TT genotype had 4.8 times greater risk of Schizophrenia compared with the CC genotype, and patients who carry the T allele had 1.79 times greater risk of Schizophrenia. No significant association was found between the rs2055314 (C/T) and rs331894 (A/G) SNPs and the risk of Schizophrenia, suggesting that cell adhesion molecules may be involved in the etiology of this disease among schizophrenic Qatari patients.

Saudi Arabia

Chaleby & Tuma (1987) studied the correlation between consanguineous marriage and schizophrenia among Saudis.  In one year, 143 were included in the study.  Out of a total of 143 patients (105 males and 38 females) with a mean age of 31.6 ± 11 years, 23 were born to first cousin parents, 13 to second cousin parents, 32 to distant-cousin parents, and 75 to non-consanguineous parents. Among the 23 patients who had first cousin parents, 12 had no family history of schizophrenic disorder, 7 had one affected family member, 3 had two affected family, and 1 had 3 or more affected family members. For the patients whose parents are second cousins, the distribution was 6, 4, 2 and 1 respectively. For the patients whose parents are distant cousins, the distribution was 26, 3, 2 and 1 respectively. As for the patients who were born to non-consanguineous parents, the distribution of family history of schizophrenia was 56, 10, 7, and 2 respectively. Results show that there is a significantly higher positive family history in patients with first or second cousin parents compared to those with non-consanguineous or distant cousin parents.

Syria

Lajin et al. (2012) investigated the role of three common polymorphisms of the folate-homocysteine metabolic pathway in an Arab population from Syria consisting of 85 schizophrenic patients and 126 healthy controls. Results indicated a strong association between MTHFR c.A1298C and schizophrenia. The variant C allele frequency was significantly higher in the patients group [40% vs 29%, OR=1.6, 95% CI (1.06-2.41), p=0.023]. A statistically significant association was found for MTHFR c.677TT genotype under the recessive model in the male patients subgroup [OR=2.6, 95% CI (1.04-6.5), p=0.036], and MTHFR c.677CT genotype under the overdominant model in the total patients group [OR=0.52 95% CI (0.29-0.92), p=0.024].

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