Screening and Congenital Abnormalities

Question 1

what are the genetic causes and risk factors of congenital abnormalities?

Answer 1

• A minority of birth defects are caused by genetic abnormalities i.e. chromosomal abnormalities (for example Down syndrome or trisomy 21) or single gene defects (for example cystic fibrosis)
  
  • Consanguinity (when parents are related by blood) also increases the prevalence of rare genetic birth defects and nearly doubles the risk for neonatal and childhood death, intellectual disability and other anomalies.

Although birth defects may be the result of one or more genetic, infectious, nutritional or environmental factors, it is often difficult to identify the exact causes.

Question 2

what are the socioeconomic and demographic causes and risk factors in congenital abnormalities?

Answer 2

• Low-income may be an indirect determinant of birth defects, with a higher frequency among resource-constrained families and countries.
  
  • An indirect determinant, this higher risk relates to a possible lack of access to sufficient nutritious foods by pregnant women, an increased exposure to agents or factors such as infection and alcohol, or poorer access to health care and screening.
  • Maternal age is also a risk factor for abnormal intrauterine fetal development. Advanced maternal age increases the risk of chromosomal abnormalities, including Down syndrome

Question 3

what are the environmental factors including infections causes and risk factors in congenital abnormalities?

Answer 3

Others occur because of environmental factors like maternal infections (syphilis, rubella, Zika), exposure to radiation, certain pollutants, maternal nutritional deficiencies (e.g., iodine, folate deficiency), illness (maternal diabetes) or certain drugs (alcohol, phenytoin).

Question 4

what are the unknown causes and risks of congenital abnormalities?

Answer 4

• While complex genetic and environmental interactions are proposed, most birth defects have unknown causes, including congenital heart defects, cleft lip or palate and club foot.

Question 5

what is prevention in terms of congenital abnormalities?

Answer 5

• ensuring adolescent girls and mothers have a healthy diet including a wide variety of vegetables and fruit, and maintain a healthy weight;
  
  • ensuring an adequate dietary intake of vitamins and minerals, particularly folic acid in adolescent girls and mothers;
  • ensuring mothers avoid harmful substances, particularly alcohol and tobacco;
  • avoidance of travel by pregnant women (and sometimes women of child-bearing age) to regions experiencing outbreaks of infections known to be associated with birth defects;
  • reducing or eliminating environmental exposure to hazardous substances (such as heavy metals or pesticides) during pregnancy;
  • controlling diabetes prior to and during pregnancy through counselling, weight management, diet and administration of insulin when required;
  • ensuring that any exposure of pregnant women to medications or medical radiation (such as imaging rays) is justified and based on careful health risk–benefit analysis;
  • vaccination, especially against the rubella virus, for children and women;
  • increasing and strengthening education of health staff and others involved in promoting prevention of congenital anomalies; and
  • screening for infections, especially rubella, varicella and syphilis, and consideration of treatment.

Question 6

what does screening involve with congenital abnormalities?

Answer 6

• Health care before and near conception (preconception and periconception) includes basic reproductive health practices, as well as medical genetic screening and counselling.
  
  • Screening can be conducted during these three phases;
  • Preconception screening
  • Peri-conception screening (3 months before conception to 3 months post conception)
  • Neonatal screening

Question 7

what does preconception screening involve?

Answer 7

• This can be useful to identify those at risk of specific disorders or of passing a disorder onto their children. Screening includes obtaining family histories and carrier screening and is particularly valuable in countries where incestuous (incest) marriage is common.

Question 8

what does peri-conception screening involve?

Answer 8

(3 months before conception to 3 months post conception)

- Maternal characteristics may increase risk, and screening results should be used to offer appropriate care, according to risk. This may include screening for young or advanced maternal age, as well as screening for use of alcohol, tobacco or other risks. 
- Ultrasound can be used to screen for Down syndrome and major structural abnormalities during the first trimester, and for severe fetal anomalies during the second trimester. Maternal blood can be screened for placental markers to aid in prediction of risk of chromosomal abnormalities or neural tube defects, or for free fetal DNA to screen for many chromosomal abnormalities. 
- Diagnostic tests such as chorionic villus sampling and amniocentesis can be used to diagnose chromosomal abnormalities and infections in women at high risk.

Question 9

what does neonatal screening involve?

Answer 9

• Screening of newborns is an important step towards detection. This helps to reduce mortality and morbidity from birth defects by facilitating earlier referral and the initiation of medial or surgical treatment
  
  • Early screening for hearing loss provides an opportunity for early correction and allows the possibility of acquiring better language, speech and communication skills. Early screening of newborns for congenital cataract also allows early referral and surgical correction which increases the likelihood of sight.
  • Newborns may be screened for certain metabolic, hematologic and endocrine disorders, many of which may not have immediately visible effects. The conditions screened for vary by country, depending on prevalence and cost. Newborn screening is increasingly conducted even in low- and middle-income countries.

Question 10

treatment to congenital abnormalities?

Answer 10

Some birth defects can be treated with medical or surgical interventions.
- Surgery with good follow up care can often mitigate the potential lethality (as in the case of congenital heart defects) or the morbidity (e.g., congenital talipes, cleft lip/palate) associated with structural birth defects. Outcomes are improved with early detection at lower levels of the system through screening, referral and management (at specialist centres in case of some issues like cardiac defects).
- Medical treatment for certain metabolic, endocrine and haematological conditions can improve quality of life. An example of this would be congenital hypothyroidism, where early detection and treatment allows full physical and mental development to healthy adulthood, whereas a missed diagnosis or unavailability of a simple treatment carries a risk of serious intellectual disability.

- Children with some types of birth defects may require long term support including physical therapy, speech therapy, occupational therapy and support from families and community.