Down's syndrome in Hyderabad, India.

Area of Science:

• Genetics
• Human Biology
• Pediatrics

Background:

• Down's syndrome (DS) is a genetic disorder associated with trisomy 21.
• Understanding the cytogenetic variations and epidemiological factors of DS is crucial for diagnosis and management.
• Previous studies have established links between maternal age and DS incidence.

Purpose of the Study:

• To perform a cytogenetic analysis of Down's syndrome cases.
• To determine the incidence of Down's syndrome in Hyderabad.
• To investigate the relationship between maternal age, sex ratio, and Down's syndrome.

Main Methods:

• Cytogenetic analysis (karyotyping) was performed on individuals with Down's syndrome.
• A survey was conducted to determine the incidence of Down's syndrome in Hyderabad.
• Comparison of maternal age and sex ratio between affected individuals and controls.

Main Results:

• Straight trisomy 21 was identified in 96.5% of affected individuals.
• Chromosomal mosaicism was found in 3.5% of cases.
• Two individuals with Down's phenotype had a normal karyotype.
• The incidence of Down's syndrome in Hyderabad was 1.17 per 1000 live births (1 in 853).
• A significant increase in mean maternal age was observed in affected individuals compared to controls.
• The sex ratio in the Down's syndrome sample was higher than in the general population.

Conclusions:

• Trisomy 21 is the predominant cytogenetic cause of Down's syndrome.
• Chromosomal mosaicism and normal karyotypes in DS phenotype warrant further investigation.
• The findings confirm the association of increased maternal age and altered sex ratio with Down's syndrome in the studied population.