Investigation of microdeletions in syndromic intellectual disability by MLPA in Iranian population

Intellectual Disabilities (ID), defined as a state of developmental deficit, result in significant limitation of intellect and poor adaptation behavior. A number of genetic factors can result in ID, such as chromosomal abnormalities, copy number variation, and single gene defect. Karyotyping is the routine method for detecting chromosomal abnormalities in patients with ID. More recently, the Multiplex Ligation-dependent Probe Amplification (MLPA) method has been applied for detecting microdeletion/duplication in patients with dysmorphism and ID.

A total of 100 patients with dysmorphism and ID have been referred to us since 2011. All patients were first evaluated clinically and a number of these individuals had normal karyotypes. We investigated duplications and deletions for 21 different microdeletion syndromes using MLPA kit (MRC-Holland).

We were able to identify aberrations in 12 (12%) patients clinically ascertained as follows: 5 Williams syndromes, 3 Miller- Dieker syndromes, 1 Sotos syndrome, 1 Angelman Syndrome, 1 Di-George syndrome and one patient with an abnormal 4p chromosomal region.

Our MLPA results indicate a high degree of concordance between the clinical data and the genotype. We suggest MLPA as the first screening method for children suffering from MR with normal karyotypes. In those cases where clinical findings were not compatible with the microdeletion syndrome identified by MLPA investigation, further studies such as FISH and aCGH were performed.