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Absence seizures with intellectual disability as a phenotype of the 15q13.3 microdeletion syndrome.

ABSTRACT: 15q13.3 microdeletions are the most common genetic findings identified in idiopathic generalized epilepsies to date, and they are present in up to 1% of patients. In addition, 15q13.3 microdeletions have been described in patients with epilepsy as part of a complex neurodevelopmental phenotype. We analyzed a cohort of 570 patients with various pediatric epilepsies for 15q13.3 microdeletions. Screening was performed using quantitative polymerase chain reaction; deletions were confirmed by array comparative genomic hybridization (CGH). We carried out detailed phenotyping of deletion carriers. In total, we identified four pediatric patients with 15q13.3 microdeletions, including one previously described patient. Two of four deletions were de novo, one deletion was inherited from an unaffected parent, and for one patient the inheritance is unknown. All four patients had absence epilepsy with various degrees of intellectual disability. We suggest that absence epilepsy accompanied by intellectual disability may represent a common phenotype of the 15q13.3 microdeletion in pediatric patients with epilepsy.

SUBMITTER: Muhle H

PROVIDER: S-EPMC3270691 | biostudies-literature |

REPOSITORIES: biostudies-literature

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A recurrent 15q13.3 microdeletion syndrome associated with mental retardation and seizures.

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Characterization of a 8q21.11 microdeletion syndrome associated with intellectual disability and a recognizable phenotype.

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Loss-of-function variants of SETD5 cause intellectual disability and the core phenotype of microdeletion 3p25.3 syndrome.

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Clinical utility gene card for: 15q13.3 microdeletion syndrome.

Project description: Not available

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OTUD7A Regulates Neurodevelopmental Phenotypes in the 15q13.3 Microdeletion Syndrome.

Project description:Copy-number variations (CNVs) are strong risk factors for neurodevelopmental and psychiatric disorders. The 15q13.3 microdeletion syndrome region contains up to ten genes and is associated with numerous conditions, including autism spectrum disorder (ASD), epilepsy, schizophrenia, and intellectual disability; however, the mechanisms underlying the pathogenesis of 15q13.3 microdeletion syndrome remain unknown. We combined whole-genome sequencing, human brain gene expression (proteome and transcriptome), and a mouse model with a syntenic heterozygous deletion (Df(h15q13)/+ mice) and determined that the microdeletion results in abnormal development of cortical dendritic spines and dendrite outgrowth. Analysis of large-scale genomic, transcriptomic, and proteomic data identified OTUD7A as a critical gene for brain function. OTUD7A was found to localize to dendritic and spine compartments in cortical neurons, and its reduced levels in Df(h15q13)/+ cortical neurons contributed to the dendritic spine and dendrite outgrowth deficits. Our results reveal OTUD7A as a major regulatory gene for 15q13.3 microdeletion syndrome phenotypes that contribute to the disease mechanism through abnormal cortical neuron morphological development.

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Clinical and Genetic Heterogeneity of the 15q13.3 Microdeletion Syndrome.

Project description:The 15q13.3 microdeletion is a recurrent CNV, presumably mediated by NAHR between segmental duplications in chromosome 15. The 15q13.3 deletion and duplication are associated with a wide range of clinical manifestations, such as intellectual deficits, seizures, autism, language and developmental delay, neuropsychiatric impairments, and behavioral problems illustrating incomplete penetrance and expressivity. This study comprises an evaluation of 106 symptomatic patients carrying the heterozygous deletion, as well as of 21 patients carrying the duplication, who have been described in previous studies. The analysis shows considerable heterogeneity for the manifestation of different key symptoms and familiar occurrence. Furthermore, 8 new patients are introduced. Convoluted familiar connections give new insights into the complexity of symptomatic manifestation. In previous studies, different opinions have been expressed as to the nature and precise location of the deletion breakpoints. Here, we show that not CHRNA7 and CHRFAM7A, but rather FAM7A or GOLGA8, serve as breakpoint regions concerning our patients. The deletion is described as heterogeneous in size. However, we assume that not only different breakpoints but also the imprecision of aCGH analysis on chromosome 15 due to segmental duplications accounts for the variability in size.

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Project description:Copy number variations (CNVs) play a key role in the pathogenesis of several diseases, including a wide range of neurodevelopmental disorders. Here, we describe the detection of three CNVs simultaneously in a female patient with evidence of severe myoclonic epilepsy, microcephaly, hypertelorism, dimorphisms as well as severe psychomotor delay and intellectual disability. Array-CGH analysis revealed a ∼240 kb microdeletion at the 7q35 inherited from her father, a ∼538 kb microduplication at the 15q13.3 region and a ∼178 kb microduplication at Xp22.33 region, both transmitted from her mother. The microdeletion in 7q35 was included within an intragenic region of the contactin associated protein-like 2 (CNTNAP2) gene, whereas the microduplications at 15q13.3 and Xp22.33 involved the cholinergic receptor nicotinic alpha 7 subunit (CHRNA7) and the cytokine receptor-like factor 2 (CRLF2) genes, respectively. Here, we describe a female patient harbouring three CNVs whose additive contribution could be responsible for her clinical phenotypes.

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Seizures and X-linked intellectual disability.

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19p13.2 Microdeletion including NFIX associated with overgrowth and intellectual disability suggestive of Malan syndrome.

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Otud7a Knockout Mice Recapitulate Many Neurological Features of 15q13.3 Microdeletion Syndrome.

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