Classical homocystinuria (HCU) is an autosomal recessive disorder caused by the deficiency of an enzyme cystathionine β-synthase (CβS) that affects the catabolic pathway of the amino acid methionine (Met) which leads to an accumulation of high levels of methionine and Homocysteine causing complications in the multi system. Therefore, a strict dietary management is crucial to maintain good biochemical control, growth parameters and avoid complications. The main objective would be to analyze the impact of the Met restricted diet on growth parameters, biochemical markers and long-term complications in patients up to 18 years. In addition, the efficacy of dietary management with additional cysteine (Cys) supplementation for the patients up to 18 years would also be examined.
The participants of the study would be recruited from the metabolic and genetics clinic in Hamad General Hospital (HGH), Qatar. All Qatari participants with confirmed diagnosis of HCU \<18 years of age will be included in the study. A mixed method study design would be used which include a cross sectional study design to assess the impact of methionine restricted diet on outcome variables and a single arm interventional study to analyze the effect of additional cysteine supplementation in patients from birth to 18 years. For the retrospective study, all the required data would be retrieved from electronic record from the Cerner of HMC and would be stored in a local drive with password protection. Further, all the eligible participants would be prospectively followed to supplement additional cysteine for the period of 6 months.
The collected data will be statistically analyzed using the "SPSS windows version 22.0 software. The study would improve better understanding of dietary management through the identified outcomes. The outcome of Cys supplementation will improve the protein tolerance, biochemical parameters, growth parameters and may standardize the Cys supplementation.
All the patients with a confirmed diagnosis of HCU by molecular and biochemical testing who are either diagnosed through NBS or LD who are following the diet
Both male and female gender from birth to 18 years
Participants depending on the age of inclusion who are willing to participate
✔ Patients with Pyridoxine responsive- homocystinuria
Patients who are solely on medication without any dietary intervention ✔ Non-Qatari Patients with a confirmed diagnosis of HCU