To date, over 70 patients, most of Ashkenazic Jewish descent, have been reported. Children with ML4 begin to exhibit developmental delay during the first year of life.
Many parents seek opthomalogic evaluations for pseudo-strabismus.
Motor and mental retardation ranges from mild to severe. The is no gross involvement of the skeletal system nor urinary mucopolysaccharide excretion. Patients currently range from one to 45 years of age. Prognosis and life expectancy beyond the latter age is unknown. Recently, a few very mildly affected children with ML4 have been diagnosed.