Body composition in patients with classical homocystinuria: body mass relates to homocysteine and choline metabolism.

INTRODUCTION: Classical homocystinuria is a rare genetic disease caused by cystathionine β-synthase deficiency, resulting in homocysteine accumulation. Growing evidence suggests that reduced fat mass in patients with classical homocystinuria may be associated with alterations in choline and homocysteine pathways. This study aimed to evaluate the body composition of patients with classical homocystinuria, identifying changes in body fat percentage and correlating findings with biochemical markers of homocysteine and choline pathways, lipoprotein levels and bone mineral density (BMD) T-scores.

METHODS: Nine patients with classical homocystinuria were included in the study. Levels of homocysteine, methionine, cysteine, choline, betaine, dimethylglycine and ethanolamine were determined. Body composition was assessed by bioelectrical impedance analysis (BIA) in patients and in 18 controls. Data on the last BMD measurement and lipoprotein profile were obtained from medical records.

RESULTS: Of 9 patients, 4 (44%) had a low body fat percentage, but no statistically significant differences were found between patients and controls. Homocysteine and methionine levels were negatively correlated with body mass index (BMI), while cysteine showed a positive correlation with BMI (p<0.05). There was a trend between total choline levels and body fat percentage (r=0.439, p=0.07). HDL cholesterol correlated with choline and ethanolamine levels (r=0.757, p=0.049; r=0.847, p=0.016, respectively), and total cholesterol also correlated with choline levels (r=0.775, p=0.041). There was no association between BMD T-scores and body composition.

CONCLUSIONS: These results suggest that reduced fat mass is common in patients with classical homocystinuria, and that alterations in homocysteine and choline pathways affect body mass and lipid metabolism.