Specific examples of metabolic disorders with prominent MRDD include phenylketonuria, maternal phenylketonuria, Lesch-Nyhan, galactosemia, and adrenoleukodystrophy. o Down Syndrome is the leading genetic cause of mental retardation, occurring in about 1/800-1000 births.
Although there are likely to be a significant number of genes on autosomes that cause mental retardation, the identification of these genes has been relatively slow. Three genes, PRSS12 on chromosome 4q26, CRBN on chromosome 3p26 and most recently CC2D1A on chromosome 19p13.
Specifically, potential causes include, but are not restricted to, chromosomal deficits (Down syndrome), inherited disorders (Fragile X syndrome, hypothyroidism), errors of metabolism, brain injury or infection (insufficient oxygen during birth, meningitis), prematurity or low birth weight, fetal malnutrition, drug or ...
There are various known causes of mental retardation:Various genetic disorders like Down's Syndrome.Certain maternal infections (rubella)during pregnancy.Alcohol abuse during pregnancy.Certain psycho social.Drug abuse during pregnancy.Maternal exposure to environmental chemicals.