A retrospective study describes a population of 11 children with riboflavin transporter deficiency (RTD) type 2, all carriers of mutations in the SLC52A2 gene, followed up between 2012 and 2022:
- the most frequent first symptom was ataxia (n=9), followed by hearing loss (n=4), nystagmus (n=2) and upper limb weakness (n=1);
- the mean age of onset of ataxia and hearing loss was three years;
- one child died at the age of three and a half, before a genetic diagnosis could be made; four children had a long delay in diagnosis (and therefore in treatment) (median delay of 13 years), while the delay for six others was shorter (median delay of one year and six months);
- high-dose riboflavin slowed or stabilized disease progression, with better results in the earliest-treated children;
- irrespective of treatment time, ataxia and vital capacity (12.5% loss over 9 years) worsened;
- optic atrophy and audiometry improved during the first year of treatment 2022 and remained stable thereafter.
Based on the Charcot-Marie-Tooth pediatric scale, the authors have developed a specific riboflavin transporter deficiency follow-up scale (RTD Pediatric Scale), which takes better account of the more marked balance disorders and proximal muscle damage specific to this deficiency. They advocate early diagnosis and treatment to avoid permanent neuronal loss.
