Childhood-onset neurodegeneration and brain atrophy: defining UBTF-related developmental regression and progressive ataxia.

The recurrent heterozygous UBTF variant c.628G>A (p.Glu210Lys) causes neurodevelopmental regression followed by progressive ataxia; elevated neurofilament light chain in patients and in the Ubtf E210K knock-in mouse reflects ongoing neuronal injury.

This study defines the natural history of UBTF-related CONDBA, caused by the heterozygous variant c.628G>A (p.Glu210Lys), and explores biomarkers in humans and mice. All 11 caregiver surveys reported neurodevelopmental regression, with a median onset of 3.5 years (range 0.5-5 years), at times following anaesthesia or illness, and 82% of individuals developed ataxia. In five participants (median age 11.8 years), wrist and ankle accelerometry showed high test-retest reliability, correlated with ataxia severity on the Brief Ataxia Rating Scale, and declined across multiple measures over the study period. Neurofilament light chain was abnormally elevated both in patients and in the Ubtf E210K knock-in mouse model. The authors conclude that wearable accelerometers provide a reliable severity measure and that neurofilament light chain may serve as a biomarker of neuronal injury.

Synthesis written by Geno'X. For the full original abstract, please refer to the source publication.

The value of this work is less genetic than preparatory: it gives an ultra-rare disease two quantitative endpoints — home accelerometry and neurofilament light chain — that will be indispensable if a therapeutic trial is ever built. The clinically actionable signal is regression triggered by anaesthesia or acute illness, which deserves to be anticipated and written into families' care plans. Caution is needed on sample size: 11 caregiver-reported surveys and 5 monitored patients cannot establish a reference trajectory, and recruitment through patient organisations favours the most severe presentations.

Analysis by Dr Thibaut Benquey