Traditional cytogenetic analysis with G-banded karyotype was established in the 1970s as the primary tool for the evaluation of intellectual disability /autism and congenital malformations.Karyotype resolution is limited to 5Mb,with a detection rate of 3％ (excluding Trisomy 21).Recently,chromosome microarray technology has revolutionised this traditional approach,with the ability to detect genome-wide copy number abnormalities with a resolution greater than 10 times that of karyotype.Chromosome microarray is now recommended as a first line test,with an additional diagnostic yield of 10 ％ in ID / autism and congenital malformations.