The natural history of variable subtypes in pediatric-onset TUBB4A-related leukodystrophy

Abstract

We establish the natural history of pediatric-onset TUBB4A-related leukodystrophy to improve clinical trial readiness through a medical record-based longitudinal study.

An international cohort of 216 individuals with pediatric-onset TUBB4A-related leukodystrophy was included. Demographic information and medical events were extracted from medical records or publications. Retrospective scores (Gross Motor Function – Metachromatic Leukodystrophy [GMFC-MLD] and Communication Function Classification System [CFCS]) were applied to assess function. Survival analysis distinguished differences in longitudinal neurocognitive function and time to event outcomes between subtypes. A decision tree predicted independent ambulation from early motor milestones.

Genotype (p.Asp249Asn vs non-p.Asp249Asn) and independent sitting by age 9 months predicted ambulation by 3 years, and stratification into three subgroups: early-infantile (non- sitting by 9 months), late-infantile (normal early milestones without the common p.Asp249Asn mutation), and a cohort of p.Asp249Asn late-infantile onset individuals. Median age at symptom onset was 0.71 years (interquartile range: [0.33, 1.50]). Common symptoms at onset include delayed development and tone abnormalities (n = 125, 66.5 % and n = 77, 43.0 %). The most common medical complications included scoliosis (N = 51/142), hip dislocation (N = 30/101), and seizures (N = 51/163). The early-infantile more severely affected cohort had a greater prevalence of G-tube placement, scoliosis, and seizure compared to the late-infantile form (p < 0.01). Peak motor and communication abilities were comparable between the p.Asp249Asn and the late infantile cohorts. Despite the acquisition of early milestones, individuals with p.Asp249Asn showed a more rapid decline of functional abilities compared to other late infantile forms (log-rank p = 0.0002).

Better understanding of TUBB4A-related leukodystrophy subtypes will improve clinical care, allow targeted preventive interventions, and permit disease stratification for future disease-modifying clinical trials.