Molecular Genetics Study on Autistic Patients in Iraq

Abstract

This study reflected on the relationship between contactin associated protein-like
2 gene (CNTNAP2) and autism spectrum disorders. The study includes forty autistic
patients and forty non autistic children as control groups (twenty unaffected sibling
and twenty unrelated children). DNA was extracted from Blood samples for
molecular detection of CNTNAP2 mutations associated with ASDs by using
Polymerase Chain Reaction (PCR) technique and sequencing analysis. PCR reaction
was performed to amplify exon 20 of CNTNAP2 gene. The PCR results revealed that
identical bands related to exon 20 of CNTNAP2 gene were present in all samples.
Therefore, five samples (four from autistic patients and one from control sibling)
were selected for genotype analysis of CNTNAP2 (exon 20) by direct sequencing.
Genotype analysis revealed that there were no any variants in CNTNAP2 (exon 20),
but it shows that two different mutations were identified in non coding region
(introns) of the CNTNAP2 gene (Single Nucleotide Polymorphisms (SNPs),ID SNP:
rs3779032 A/G in 2118282 position and ID SNP: rs3779031 A/C in 2118436
position). rs3779031 A/C are located at intron 19 while SNP rs3779032 A/G are
located at intron 21. These mutations were seen only in autistic patients but not
present in control sample. The current study showed that two common SNPs
(rs3779031 and rs3779032) in CNTNAP2 were strongly associated with ASDs,
where the frequencies of these SNPs were relatively high. SNP rs3779032 were
identified in two autistic patients while rs3779031 were identified in three autistic
patients from four unrelated families with ASDs.