TUBB4A de novo mutations cause isolated hypomyelination

Area of Science:

• Neurogenetics
• Leukodystrophy Research
• Molecular Medicine

Background:

• Hypomyelinating leukodystrophies present diagnostic challenges, with many cases remaining unresolved.
• The genetic basis for many leukodystrophies is still being elucidated.
• TUBB4A mutations are known to cause hypomyelination, typically with basal ganglia and cerebellar atrophy.

Purpose of the Study:

• To investigate the genetic cause of isolated hypomyelination in patients without classic MRI findings.
• To identify novel mutations in the TUBB4A gene associated with hypomyelinating leukodystrophy.
• To expand the understanding of the clinical and imaging spectrum of TUBB4A-related disorders.

Main Methods:

• Whole-exome sequencing was performed on patients from two large leukodystrophy bioregistries.
• Magnetic resonance imaging (MRI) and clinical data were reviewed for all included patients.
• Genetic analysis focused on identifying de novo mutations in the TUBB4A gene.

Main Results:

• Five unrelated patients with hypomyelination and mild cerebellar atrophy, but without basal ganglia abnormalities, were identified.
• Novel de novo mutations in the TUBB4A gene were discovered in these patients.
• Clinical and imaging data revealed a spectrum of manifestations associated with these TUBB4A mutations.

Conclusions:

• The phenotype associated with TUBB4A mutations extends beyond hypomyelination with basal ganglia and cerebellar atrophy.
• Isolated hypomyelination or hypomyelination with non-specific cerebellar atrophy should prompt consideration of TUBB4A mutation screening.
• This research broadens the diagnostic criteria for TUBB4A-related hypomyelinating conditions.