Table 1 summarizes the most common CBS mutations that were reported in different parts of the world. Studies showed that CBS is common in some countries, including Ireland (1 in 65,000), Germany (1 in 17,800), Norway (1 in 6400), and reached the highest prevalence in Qatar (1 in 1800) [17]. Homocystinuria is reported as an autosomal recessive disease, where the marriage of two CBS carriers’ mutant genes could result in having children with homocystinuria. The gene discussed is CBS; the disease is autosomal recessive disease.