Triple test screening for Down syndrome: an Egyptian-tailored study

Area of Science:

• Medical Genetics
• Prenatal Screening
• Biochemistry

Background:

• Down syndrome (DS) screening in Egypt faces challenges with inaccurate results due to a lack of country-specific data for risk calculation.
• Current triple test screening lacks a unified policy for program implementation in Egypt.
• The incidence of DS in Egypt ranges from 1:555 to 1:770.

Purpose of the Study:

• To calculate and validate triple marker medians specific to Egyptian pregnant women.
• To recommend standardized program conventions for unifying DS screening in Egypt.
• To enhance the accuracy of prenatal Down syndrome screening for the Egyptian population.

Main Methods:

• Conducted a study on 668 Egyptian women between 15-20 weeks of gestation.
• Measured chorionic gonadotropin (CG), alpha-fetoprotein (AFP), and unconjugated estriol (uE3) using Siemens Immulite analyzer.
• Calculated medians, regressed against gestational age, adjusted for maternal weight, and used Prisca software for risk assessment.

Main Results:

• Derived log-linear and exponential equations for AFP/uE3 and CG, respectively, showing patterns similar to Asian and Western medians.
• Estriol levels were consistently lowest, while CG and AFP were intermediate.
• A linear reciprocal model adjusted parameters for a median Egyptian weight of 78.2 kg, achieving a 6.7% positive rate and 1.00 grand MoM.

Conclusions:

• The study provides recommendations for a Down syndrome screening program tailored to Egyptian specificities.
• Adoption of these recommendations is expected to lead to a successful and unified national DS screening program.
• Validated Egyptian-specific medians and adjusted screening protocols enhance the reliability of DS detection.