Chromosomal abnormalities in a referred population for cytogenetic analysis: four years experience, human genetics department, national research center, Egypt

Abstract EN

-Over a period of 4 years, 2454 cases /ere referred for karyotype analysis at the Cytogenetic Laboratory, Human Genetics Jepartment, National Research Center NRC).

The aim was to reach an accurate liagnosis and classification of different /pes of chromosomal anomalies.

Different :ytogenetic techniques were used ncluding: Giemsa Trypsin banding, high esolution, induction of fragility and FISH.

According to the causes of referral the jounseling group represented the highest requency being 23.5% of all cases, :ouples with previous birth of congenital nalformed baby represented 36% of the jounseling group.

Chromosomal abnormalities were letected in 24.4% of the total 2454 (aryotypes performed, autosomal abnormalities were present in 61.7% of :hem.

Down syndrome represented the Highest numerical aberrations, being 22.3%.

Structural autosomal abnormalities were present in 37.5% of all anomalies, inversion was the highest, being 9.5% followed by deletion and translocation.

Sex chromosome abnormalities were present in 38.3%, Turner syndrome represented the highest sex chromosome anomalies , being 15.3% of the chromosomal aberrations followed by the Klinefelter syndrome 9.7% .The mosaic cell line were present in 28% of all aberrations.

Fluoresence in situ hybridization (FISH) technique were performed to confirm cases with mosaic cell line , ring X, triple X.

This study emphasizes the importance of thorough cytogenetic examination and application of recent cytogenetic techniques specially FISH to reach an accurate diagnosis and classification.