Table 1

Classification of the patients according to degree of mental retardation, familial occurrence, and association with malformations/dysmorphism

Mental retardation	Mild	Moderate	Severe	Unknown^1-150	Total
Number	44	62	55	39	200
Familial	15	15	12	11	53
Sporadic	29	47	43	28	147
Isolated	13	8	2		23
Associated	28	53	52	27	160
Unknown	3	1	1	12	17

↵1-150 Unspecified degree of mental retardation or children below testing age.