Chromosomal abnormality in 500 : referred cases in Bahrain

Abstract EN

Objective: Study the incidence and pattern of major chromosomal abnormalities in a Bahraini population suspected of having chromosomal abnormality on the basis of physical and/or development clinical features.

Design: Cytogenetic studies were performed on five hundred patients.

Setting: Genetic Clinic, Salmaniya Medical Centre, Bahrain during the period from 1984-1991.

Main Outcome: 134 (27 %) patients had abnormal karyotype, 97 (19 %) patients had numerical abnormalities and 37 (7 %) had structural chromosomal abnormalities.

The majority of patients with numerical abnormalities (66 %) were Down Syndrome or trisomy 21, 4 % were having trisomy 13, and 4 % were having trisomy 18.

Cases of X chromosome abnormalities were found in 13 % of the abnormal causes, while 12 % were having abnormality of other chromosomes.

Conclusion: This study demonstrates the spectrum of chromosomal abnormality in Bahrain but not the prevalence of these abnormalities in the country as it was only performed on a small number of patients.

Bahrain Med Bull 1996:18(1): It is well known that too many or too few copies of genes can upset the normal process of development.

These abnormalities result from gross imbalances in the number and action of genes.

A general rule is that the greater the imbalance, the more severe is the abnormality.

Some imbalance is sufficiently small to have almost no effect on development, while other larger ones are lethal and may lead to death of embryo or child at an early age1-5.

Singh in 1977 investigated 451 referred cases suspected in South Carolina, USA of having chromosomal abnormalities due to physical and/or developmental abnormalities, and he found changes in 28.8 %.

In a comparable study, Verma in 1980 investigated 357 referred cases from New York, USA and found chromosomal abnormalities in 27.2 % of these cases, while Shah in Ahmedbad in India studied 205 referred cases and reported 39.58 % (Table 1)7-8