PAFAB1H1 deletions and 17p13.3 microdeletions with no PAFAB1H1 deletion

Clark GD. Platelet-Activating Factor Acetylhydrolase and Brain Development. Enzymes. 2015;38:37-42.

Abstract

The heterotrimeric brain platelet-activating factor acetylhydrolase (PAFAH1B1) contains two catalytic subunits and a regulatory subunit. This complex plays important, surprising roles in brain development and in spermatogenesis. The regulatory subunit, PAFAH1B1 (LIS1 protein), is critically regulated and when deficient leads to the devastating human neurological disorder Lissencephaly, or smooth brain. The role of the protein in brain development is not the catalysis of platelet-activating factor, rather the entire brain platelet-activating factor acetylhydrolase complex serves a signaling role, coordinating important pathways in brain development. The role of this complex in spermatogenesis was not foreseen, but appears to function to regulate a critical level of the PAFAH1B1 protein, such that too much of this protein or too little of this protein can lead to a disruption of spermatogenesis. Brain platelet-activating factor is thus a signaling complex, important for brain development and for spermatogenesis.

Barros Fontes MI, Dos Santos AP, Rossi Torres F, Lopes-Cendes I, Cendes F, Appenzeller S, Kawasaki de Araujo T, Lopes Monlleó I, Gil-da-Silva-Lopes VL. 17p13.3 Microdeletion: Insights on Genotype-Phenotype Correlation. Mol Syndromol. 2017 Jan;8(1):36-41.

Abstract

Microdeletions in the chromosomal region 17p13.3 are associated with neuronal migration disorders, and PAFAB1H1 is the main gene involved. The largest genomic imbalances, including the YWHAE and CRK genes, cause more severe structural abnormalities of the brain and other associated dysmorphic features. Here, we describe a 3-year-old boy with a microdeletion in 17p13.3 presenting with minor facial dysmorphisms, a cleft palate, neurodevelopmental delay, and behavioral disorder with no structural malformation of the brain. The patient was evaluated by a clinician using a standard protocol. Laboratory investigation included GTG-banding, whole-genome AGH, and array-CGH. Whole-genome AGH and array-CGH analysis identified an estimated 2.1-Mb deletion in the 17p13.3 region showing haploinsufficiency of the YWHAE, CRK, H1C1, and OVCA1 genes and no deletion of PAFAH1B1. The complex gene interaction on brain development and function is illustrated in the genotype-phenotype correlation described here. This report reinforces the importance of the 17p13.3 region in developmental abnormalities and highlights the weak implication of the HIC1 and OVCA1 genes in palatogenesis.

Candelo E, Caicedo G, Mejia L, Pachajoa H. Chromosome 17p13.3 microdeletion syndrome with unaltered PAFAH1B1 gene. Neurologia. 2016 Dec 8. pii:S0213-4853(16)30214-6. (May be available in English, but I did not succeed in finding it.)

Inspired by a patient with PAFAB1H1 deletion.