Thursday, June 14, 2018

CELF4 haploinsufficiency

Inspired by a patient

Barone R, Fichera M, De Grandi M, Battaglia M, Lo Faro V, Mattina T, Rizzo R. Familial 18q12.2 deletion supports the role of RNA-binding protein CELF4 in autism spectrum disorders. Am J Med Genet A. 2017 Jun;173(6):1649-1655.

Deletion of 18q12.2 is an increasingly recognized condition with a distinct neuropsychiatric phenotype. Twenty-two patients have been described with overlapping neurobehavioral disturbances including developmental delay, intellectual disability of variable degree, seizures, motor coordination disorder, behavioral/emotional disturbances, and autism spectrum disorders. The CUGBP Elav-like family member 4 (CELF4) gene at 18q12.2 encodes a RNA-binding protein that links to RNA subsets involved in pre- and postsynaptic neurotransmission including almost 30% of potential autism-related genes. Haploinsufficiency of CELF4 was associated with an autism or autistic behavior diagnosis in two adult patients with de novo 18q12.2 deletions. We report on a girl and her mildly affected mother with a 275 kb deletion at 18q12.2 involving CELF4 and KIAA1328 whose disruption is not associated with any known disease. The child was diagnosed with syndromic intellectual disability and autism at 6 years of age. Her mother had minor dysmorphisms, mild intellectual disability, and autistic behavior. The deleted region reported in this family is one of the smallest so far reported at 18q12.2. This is also the first full clinical description of maternally inherited CELF4 haploinsufficiency. The present study refines the molecular and neuropsychiatric phenotype associated with 18q12.2 deletion leading to CELF4 haploinsufficiency and provides evidence for a role for CELF4 in brain development and autism spectrum disorders.

Halgren C, Bache I, Bak M, Myatt MW, Anderson CM, Brøndum-Nielsen K, Tommerup N. Haploinsufficiency of CELF4 at 18q12.2 is associated with developmental and behavioral disorders, seizures, eye manifestations, and obesity. Eur J Hum Genet. 2012 Dec;20(12):1315-9.

Only 20 patients with deletions of 18q12.2 have been reported in the literature and the associated phenotype includes borderline intellectual disability, behavioral problems, seizures, obesity, and eye manifestations. Here, we report a male patient with a de novo translocation involving chromosomes 12 and 18, with borderline IQ, developmental and behavioral disorders, myopia, obesity, and febrile seizures in childhood. We characterized the rearrangement with Affymetrix SNP 6.0 Array analysis and next-generation mate pair sequencing and found truncation of CELF4 at 18q12.2. This second report of a patient with a neurodevelopmental phenotype and a translocation involving CELF4 supports that CELF4 is responsible for the phenotype associated with deletion of 18q12.2. Our study illustrates the utility of high-resolution genome-wide techniques in identifying neurodevelopmental and neurobehavioral genes, and it adds to the growing evidence, including a transgenic mouse model, that CELF4 is important for human brain development.

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