Investigating the effects of a single ASPM variant (c.8508_8509) on brain architecture among siblings in a consanguineous Pakistani family.

BACKGROUND: Autosomal Recessive Primary Microcephaly (MCPH) is a rare, neurodevelopmental disorder associated with mild to severe mental retardation. It is characterized by reduced cerebral cortex that ultimately leads to reduction in skull size less than - 3 S.D below the mean for normal individuals having same age and sex. Till date, 30 known loci have been reported for MCPH. METHODS: In the present study, Sanger sequencing was performed followed by linkage analysis to validate the mutation in ASPM gene of the consanguineous Pakistani clans. Bioinformatics tools were also used to confirm the pathogenicity of the diseased variant in the gene. MRI scan was used to compare the brain structure of both the affected individuals (Aslam et al. in Kinnaird's 2nd International Conference on Science, Technology and Innovation, Lahore, 2023). RESULTS: Our study described a consanguineous family with two patients with a known ASPM (MCPH5) variant c.8508_8509delGA causing a frameshift mutation in exon 18 which located in calmodulin-binding IQ domain of the ASPM protein. The salient feature of this study is that a single variant led to significantly distinct changes in the architecture of brain of both siblings which is further confirmed by MRI results. The computation analysis showed that the change in the conservation of this residue cause this variant highly pathogenic. Carrier screening and genetic counselling were also remarkable features of this study (Aslam et al. in Kinnaird's 2nd International Conference on Science, Technology and Innovation, Lahore, 2023). CONCLUSION: This study explores the extraordinary influence of a single ASPM variant on divergent brain structure in consanguineous siblings and enable us to reduce the incidence of further microcephalic cases in this Pakistani family (Aslam et al. in Kinnaird's 2nd International Conference on Science, Technology and Innovation, Lahore, 2023).

The molecular genetics of selective tooth agenesis.

Selective tooth agenesis is a congenital disorder divided into two types based on the number of missing teeth, i.e. hypodontia which is the absence of <6 teeth and oligodontia which is agenesis of >6 permanent teeth excluding the third molars. As the prevalence of tooth agenesis is higher in populations with Arab and Asian descent, it is intriguing to probe deeper into the molecular aspects of this disorder. Selective tooth agenesis inherits as autosomal dominant, autosomal recessive or X-linked dominant mode of inheritance. The 10 loci identified are selective tooth agenesis 1 through 9 and selective tooth agenesis X1. Genes for 8 of these loci have been characterised while the causative genes for selective tooth agenesis 2 and 5 still remain to be elucidated. The current broad-spectrum review was planned to discuss the molecular genetics of all 10 loci mapped with selective tooth agenesis, their mode of inheritance as well as the proteins encoded by these genes, their roles and their interactions.