Functional analysis of a novel intronic variant of MCPH1 with autosomal recessive primary microcephaly

Abstract

Autosomal Recurrent Primary Microscopic (MCPH, OMIM: 251200) is a neurodevelopmental disorder that is characterized by a noticeable decrease in brain size, particularly in the cerebral cortex, but with a normal brain structure and a non-progressive intellectual disability. MCPH1 has been identified as the gene that triggers primary microcephaly (MCPH1，OMIM: 607117). Here we report a case of autosomal recessive primary microcephaly as caused by a novel variant in the MCPH1 gene. Head circumference was measured by Magnetic Resonance Imaging (MRI), while the Wechsler Intelligence Scale was used to evaluate the intelligence of the individual being tested. B-ultrasound was used to assess gonadal development, and semen routine was used to assess sperm status. The whole-exome sequencing (WES) was performed on the proband. Sanger sequencing was conducted on the parents of the proband to determine if the novel variant in the MCPH1 gene was present. The effect of the mutation on the splicing of MCPH1 was verified by minigene approach. It was observed that the proband had autosomal recessive primary microcephaly and azoospermatism. A novel splice-site homozygous mutation (c.233+2T > G) of the MCPH1 gene was identified, which inherited from his parents. Minigene approach confirmed that c.233+2T > G could affect the splicing of MCPH1. Therefore, our findings contributed to the mutation spectrum of the MCPH1 gene and may be useful in the diagnosis and gene therapy of MCPH.

Keywords

• MCPH1
• c.233+2T>G
• Microcephaly
• Minigene