Identification of a Novel Nonsense ASPM Mutation in a Large Consanguineous Pakistani Family Using Targeted Next-Generation Sequencing

Aims: To identify the pathogenic mutation underlying microcephaly primary hereditary (MCPH) in a large consanguineous Pakistani family. Methods: A five-generation family with an autosomal recessive transmission of MCPH was recruited. Targeted next-generation DNA sequencing was carried out to analyze the genomic DNA sample from the proband with MCPH using a previously designed panel targeting 46 known microcephaly-causing genes. Sanger sequencing was performed to verify all identified variants. Results: We found a novel homozygous nonsense mutation, c.7543C>T, in the ASPM gene. This mutation led to the substitution of an arginine with a stop codon at amino acid residue 2515 (p.Arg2515Ter). The mutation cosegregated with the MCPH phenotype in all affected and obligate carrier family members, but was not present in public databases (dbSNP147, Exome Variant Server, the 1000 Genomes Project, Exome Aggregation Consortium, Human Gene Mutation Database, and ClinVar) or 200 control individuals. The c.7543C>T mutation in ASPM may activate nonsense-mediated mRNA decay pathways and could underlie the pathogenesis of MCPH through a loss-of-function mechanism. Conclusions: The c.7543C>T (p.Arg2515Ter) mutation in ASPM is a novel pathogenic mutation for the typical MCPH phenotype in this family.