Abnormal Weight and Body Mass Index in Children with Juvenile Huntington's Disease

The hallmark clinical manifestation of Huntington's disease (HD), namely lower weight and BMI has been reported in prodromal HD (PreHD) adults and also in PreHD children. Here, we aim to evaluate anthropometric measures of growth and development (height, weight, body mass index (BMI)) in a group of children, adolescents, and young adults diagnosed with Juvenile Onset Huntington's Disease (JHD).

Growth measures for 18 JHD patients, documented prior to or shortly after diagnosis, were obtained through medical records. JHD growth measures were compared to a large sample (n = 274) of healthy children, as well as the Center for Disease Control (CDC) growth norms.

After controlling for sex and age, the JHD subjects had no significant differences in height. However, they were an average of 10% lower than controls in weight and BMI. Using CDC norms, the JHD subjects had the same pattern of normal height but decrement in weight. Length of cytosine-adenine-guanine (CAG) repeat in the huntingtin gene was significantly correlated to measures of weight with longer CAG repeats being associated with more severe weight reduction. A subset of 4 subjects had measures that pre-dated onset of any symptom and were therefore prodromal JHD (preJHD). These subjects also had a significant decrement in BMI compared to CDC norms.

Children with JHD have normal height, but significantly reduced weight and BMI, indicative of a specific deficit in body weight. As the preJHD subjects were also low in BMI, this suggests that these changes are directly due to the effect of the mutated gene on development, rather than symptom manifestation of the disease itself. Potential mechanisms of the weight decrement include energy deficiency due to mitochondrial dysfunction during development.