CBS and hyperinsulinemic hypoglycemia, familial, 4: These skeletal manifestations give older patients an appearance similar to that of Marfan syndrome (Smith 1967; Morreels et al 1968; Beals 1969; Brenton et al 1972; Schedewie et al 1973; Boers et al 1983, 1984; Mudd et al 1985) but CBS deficiency can be distinguished by the presence of osteoporosis (Carson 1982).