Clinical and Functional Characterization of the Recurrent TUBA1A p.(Arg2His) Mutation

Area of Science:

• Neuroscience
• Genetics
• Developmental Biology

Background:

• The TUBA1A gene is crucial for fetal brain development, encoding tubulin alpha-1A, a key component of microtubules.
• Microtubules are essential for neurogenesis, neuronal migration, and cortical organization.
• Mutations in TUBA1A are linked to various brain malformations.

Purpose of the Study:

• To investigate the effects of a specific de novo missense mutation (c.5G>A, p.(Arg2His)) in the TUBA1A gene.
• To characterize the resulting brain phenotypes and understand the mutation's functional impact on microtubule dynamics.

Main Methods:

• Next-generation sequencing to identify the mutation in four unrelated patients.
• Clinical phenotyping and detailed comparison of brain malformations.
• Computer-based protein structure modeling and heterologous expression in HEK-293 cells to assess functional effects.

Main Results:

• All four patients shared the same de novo TUBA1A mutation, p.(Arg2His), and exhibited similar brain phenotypes with mild variability.
• Common features included developmental delay, microcephaly, cerebellar hypoplasia, corpus callosum abnormalities, small pons, and dysmorphic basal ganglia.
• The p.(Arg2His) mutation was found to subtly impair microtubule function, likely by affecting inter-dimer interactions.

Conclusions:

• The recurrent TUBA1A mutation c.5G>A, p.(Arg2His), leads to a recognizable spectrum of brain malformations.
• Subtle functional impairment of microtubules by this mutation may explain the observed phenotypic variability, influenced by genetic background and environmental factors.