mith-Lemli-Opitz syndrome is a multiple congenital anomalies/mental retardation syndrome caused by a defect in cholesterol synthesis. Patients present with Congenital heart disease, Vomiting, feeding difficulties, constipation, toxic megacolon, electrolyte disturbances, and failure to thrive. Visual loss may occur because of cataracts, optic nerve abnormalities, or other ophthalmologic problems. Hearing loss is also seen.

Williams syndrome is characterised by Characteristic facial appearance, hart and blood vessel problems, hypercalcemia, Low birth-weight, Feeding problems, Dental abnormalities, Kidney abnormalities, hernias, Hyperacusis, Musculoskeletal problems, Overly friendly (excessively social) personality, Developmental delay, learning disabilities and attention deficit.