Genetic disorders occur when there are problems in the genes or chromosomes of a fetus. it could lead to chromosomal disorders such as Down’s syndrome Patau’s syndrome, or Edward’s syndrome. Down syndrome is the most frequently occurring chromosomal disorder, with an incidence of 1/660 live births in Malaysia.

There has been no evidence that it is due to parental behaviour, inheritance, or environmental factors. Many babies with birth defects are born to couples with no risk factors.

Who are at an increased risk:

  • Family or personal history of birth defects.
  • Previous child with a birth defect.
  • Certain medicines used around the time of conception or exposure to harmful agents.
  • Exposure to viral infection during pregnancy.
  • Diabetes before pregnancy.
  • A woman aged 35 years or older when the baby is due.

The risk of having a baby with birth defects disorders can be determined through prenatal screening tests. Screening tests are easy to perform and do not pose any risks to the fetus. A variety of tests are available that can be done based on the stage or trimester of Your pregnancy. If results of screening are abnormal with an indication of increased risk, diagnostic testing is offered.

Available Tests to Detect Genetic Abnormalities During Pregnancy

First Trimester Screen (FTS) 

  • Screening test
  • Done between 11— 13 weeks 6 days of pregnancy
  • Maternal blood + ultrasound scan
  • Detection rate: >90%

Second Trimester Screen (STS)

  • Screening test
  • Done between 15 — 20 weeks of pregnancy
  • Maternal blood
  • Detection rate: 77%

Chromosomes Check

  • Diagnostic test
  • Done between 15 — 20 weeks of pregnancy
  • Amniotic fluid/ Chorionic Villus/ Foetal Blood
  • Detection rate: 99.9%

FAQ regarding Genetic Disorders

  1. What are the advantages of First Trimester Screening (FTS)?

Allows you to know your baby’s condition earlier in pregnancy to allow more time for informed decisions to be made. Detection rate is higher than that of the Second Trimester Screening

  1. Can FTS identify other birth defects besides Down’s Syndrome?

Yes. If can identify cardiac defects, other chromosomal abnormalities such as Trisomy 18 (Edward’s syndrome), Trisomy 13 (Patau’s syndrome) and other rare genetic disorders.

  1. What is the difference between screening tests and diagnostic test?

Screening tests are non-invasive, therefore does not pose any dangers to the foetus. Diagnostic tests are invasive; there is a risk of miscarriage.

References: 1. Kiwanis Down Syndrome Foundation, 2. The American College of Obstetricians and Gynecologists. 3. Nicolaides K.H., The 11-13’6 weeks scan, Fetal Medicine Foundation 2004, Introduction page; 4. Mann K Strategies for the rapid prenatal diagnosis of chromosome aneuploidy (2004) Eur. J Hum. Genet. 12, 907-915; 5.
Adapted from © Copyright 2008 DNA Laboratories Sdn. Bhd. All Rights Reserved. MS/EC/B2C002

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