Friedreich ataxia was found to affect both weight gain and linear growth in adult and pediatric patients, according to results of a prospective natural history study, published in Neurology Genetics.
The progressive neurodegenerative movement disorder is associated with ataxia, areflexia, dysarthria, sensory loss, and weakness. The mean age for onset is between 10 and 15 years of age. Metabolic stress and characteristics from mitochondrial disorders, such as failure to thrive, exercise intolerance, and excess fatigue, can affect both weight gain and growth in this patient population. Patients with Friedreich ataxia commonly have cardiomyopathy, scoliosis, and diabetes comorbidities.
The objective of this study was to assess the association between body mass index (BMI) and height and clinical characteristics in Friedreich ataxia.
The Friedreich Ataxia Clinical Outcome Measure Study (FACOMS) recruited 961 participants at 12 international sites. Age- and gender-specific body mass index (BMI) and height Z-scores were calculated using the Centers for Disease Control and Prevention 2000 references. Trends in growth were compared with data from the Bone Mineral Density in Childhood Study (n=1535).
The pediatric (n=402) and adult (n=559) cohorts were aged median 12 (interquartile interval [IQI], 10-15) and 30 (IQI, 23-42) years, 47% and 52% were girls or women, symptom onset at 7 (IQI, 5-10) and 15 (IQI, 10-20) years of age (P <.001), and mean height Z-scores were 0.03±1.06 and 0.05±0.94, respectively.
The children had a higher burden of cardiomyopathy (64% vs 41%; P <.001) and scoliosis (83% vs 71%; P <.001) but lower burden of diabetes (1.5% vs 7.0%; P <.001). More children were underweight (17% vs 7%) or had normal weight (75% vs 60%) and fewer were overweight (8% vs 33%; P <.001) compared with the adults.
Among the pediatric cohort, BMI Z-scores were associated with gender (b, -0.40; 95% CI, -0.69 to -0.11; P <.01) and for adults, age at measurement was a significant predictor (b, 0.09; 95% CI, 0.01-0.16; P <.05).
For height Z-scores, the significant predictors among children were BMI Z-score (b, 0.19; 95% CI, 0.08-0.30; P <.001), highest disease severity compared with lowest severity (b, -1.05; 95% CI, -1.83 to -0.28; P <.01), and age at measurement (b, -0.07; 95% CI, -0.12 to -0.01; P <.05). Only BMI Z-score was a significant predictor of height Z-scores among the adults (b, -0.03; 95% CI, -0.05 to -0.001; P <.05).
Compared with data from healthy individuals, after puberty, girls with Friedreich ataxia were shorter and boys with Friedreich ataxia were taller (P <.001). Peak height velocity was slower among girls with Friedreich ataxia by 0.2 cm/year (P <.001) and boys with Friedreich ataxia started their pubertal growth spurt one year later than the general population (P <.001).
This study was limited by the high amount of missing data and the fact that data tended to be missing from individuals with more severe disease.
“FRDA [Friedreich ataxia] affects both weight gain and linear growth. These insights will inform assessments of affected individuals in both research and clinical settings,” concluded the researchers.
Paten M, McCormick A, Tamaroff J, et al. Body Mass Index and Height in the Friedreich Ataxia Clinical Outcome Measures Study. Neurol Genet. November 12, 2021. doi:10.1212/NXG.0000000000000638