Intellectual Deficiency, Unclassified

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WHO-ICD-10 version:2010

Congenital malformations, deformations and chromosomal abnormalities

Other congenital malformations

Mode of Inheritance

Autosomal recessive

Description

Mental retardation is a leading feature of many mendelian syndromes. In addition, studies in mental institutions  show that mental retardation of unclassified type occurs in multiple sibs in a considerable number of cases. Some of these doubtless represent rare recessive disorders. [From OMIM]

Epidemiology in the Arab World

View Map
Subject IDCountrySexFamily HistoryParental ConsanguinityHPO TermsVariantZygosityMode of InheritanceReferenceRemarks
600237.1Saudi ArabiaMaleNoYes Global developmental delay; Severe postn...NM_003325.4:c.41A>GHomozygousAutosomal, RecessiveAnazi et al. 2016
612256.1United Arab EmiratesMaleYesNo Global developmental delay; Delayed spee...NM_014975.3:c.3539T>GHeterozygousBen-Mahmoud et al. 2020 Proband with de novo...
614235.1.1OmanMaleYesYes Global developmental delay; Intellectual...NM_173791.5:c.2197_2200delHomozygousAutosomal, RecessiveAl-Amri et al. 2022
614235.1.2OmanMaleYesYes Global developmental delay; Intellectual...NM_173791.5:c.2197_2200delHomozygousAutosomal, RecessiveAl-Amri et al. 2022 Sibling of 614235.1....
614235.1.3OmanFemaleYesYes Global developmental delay; Intellectual...NM_173791.5:c.2197_2200delHomozygousAutosomal, RecessiveAl-Amri et al. 2022 Sibling of 614235.1....
614235.2United Arab EmiratesMaleYes Global developmental delay; Intellectual...NM_173791.5:c.894C>GHomozygousAutosomal, RecessiveAl-Amri et al. 2022

Other Reports

Lebanon

Megarbane et al. 2002d reported on monozygotic twin brothers exhibiting intellectual disability, short stature, macrocephaly, brachydactyly, clinodactyly, cryptorchidism, and prelingual sensorineural deafness. One of the brothers passed away from a cradiac arrest following acute respiratory infection. A cryptic chromosomal rearrangement involving a partial 6p trisomy and partial 11q monosomy was identified in the surviving brother. The father exhibited a balanced reciprocal translocation.

Delague et al. 2006 screened for subtelomeric rearrangements in 45 patients from 34 independent families, exhibiting intellectual disability with normal karyotype and negative biochemical tests. The patients exhibited one or more of the following: growth abnormalities, dysmorphic features, and/or malformations. 85 fluorescently labelled STR markers were genotyped in each patient and their parents. 5 cryptic rearrangements were identified, 3 of which were confirmed using FISH.

Haddad et al. 2009 reported on a female patient with mild intellectual disability and dysmorphic features. A de novo balanced translocation t(5;18)(q21.3;q21.32) was identified in the patient. The tyrosine kinase gene FER was identified as a candidate gene at the translocation break point; however molecular analysis and RT-qPCR showed that the gene was uninterrupted by the break and showed no modififed expression in lymphoblastoid cell cultures. 

Makrythanasis et al. (2014) studied 50 families using WES analysis to diagnose patients with recessive disorders. The cohort included a Lebanese family with syndromic ID and developmental delay and  another with syndromic ID and neurological deficit. 

Choucair et al. (2015) studied a cohort of 149 Lebanese patients with Intellectual disability or develomental delay and identified a total of 20 pathogenic and six likely pathogenic CNVs. 

 

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