Genetic Conditions and Birth Defects

1. Genetic Conditions and Birth Defects Camila Vieira Shanahan, MS, CGC Genetic Counselor Fullerton Genetics Center February 17, 2012

2. Outline • Prenatal Exposures • Types of Genetic Conditions • Multifactorial disorders • Chromosomal disorders • Single gene disorders • Mitochondrial disorders • Genetics Clinic

3. What are birth defects? • Birth defects are defined as abnormalities of structure, function, or body metabolism that are present at birth. • These abnormalities lead to mental or physical disabilities or are fatal. • There are more than 4,000 different known birth defects ranging from minor to serious.

4. With every pregnancy, the chance for a baby to be born with a birth defect is… 3-5%

5. Pregnancy Timeline

6. Maintaining a healthy lifestyle is important during pregnancy

7. Which of the following can cause more harm to a fetus? • Cigarettes • Crack/Cocaine • Heroin • Alcohol

8. “Alcohol causes more damage to the developing fetus than any other substance, including marijuana, heroin, and cocaine.” Institute of Medicine, 1996

9. Effects of Alcohol • Consumption of alcohol during pregnancy can have devastating effects on the baby • No amount of alcohol is okay

10. Fetal Alcohol Syndrome • The name commonly given to the group of physical features found in children exposed to alcohol during pregnancy • Common features include: • Classic facial features • Growth problems in both weight and height • Heart, liver, and kidney problems • Vision and hearing problems • Difficulties with learning, attention, memory, and problem solving

11. Characteristic FAS Facial Features Source: www. niaaa.nih.gov/ Source: www.come-over.to/FASCRC/

12. Fetal Alcohol Syndrome • Approximately 1 in every 100 children born have some effects of alcohol • The leading known preventable cause of mental retardation and birth defects • It is preventable by avoiding alcohol during pregnancy

13. Fetal Alcohol Syndrome • One child with FAS costs about $800,000 in health care costs over their lifetime • It is found in all racial and economic groups • The effects are not reversible and do not go away with time

15. Effects of Smoking • Smoking during pregnancy can also affect the baby • Babies born to women who smoke are usually small at birth (under 5 ½ pounds) • Preterm delivery is also common • Possible low IQ

16. Effects of Medications • Medications you take can also be harmful during pregnancy • The most devastating ones include Accutane and anti-seizure medications • Ask your doctor about medications you are taking

17. Pregnancy Exposure ProgramFullerton Genetics Center (800) 532-6302

18. Effects of Good Prenatal Care • Good prenatal care is the first step to ensuring a healthy baby • This includes eating healthy, exercising, getting enough sleep, and seeing your doctor • However, there is never any guarantee

19. Types of genetic diseases • Multifactorial disorders • Chromosomal disorders • Single gene disorders • Mitochondrial disorders

20. Multifactorial Disorders • No clear inheritance pattern • Recurrence risk difficult to estimate • Combination of genetic and environmental factors

21. The Neural Tube

22. Neural Tube Defects • If the neural tube doesn’t zipper on the back, the baby will have spina bifida • If the tube is open at the head, the baby will have anencephaly

23. Spina Bifida • Occurs in 1 out of every 1,000 births • One of the most common birth defects • Cost to society is about $532,000 for each child with spina bifida • Surgery is done immediately following birth to close the opening • Some surgery is also being done while the baby is still in the womb

24. Spina Bifida

25. Spina Bifida Three types: • Spina Bifida Occulta • Vertebrae are slightly malformed • Meningocele • Opening in the vertebrae; membranes and fluid protrude • Myelomeningocele • Opening in the vertebrae; membranes, fluid, and spinal cord protrude

26. Spina Bifida

27. Spina Bifida- Who’s at Increased Risk? • Women who have previously had a child with a NTD • Women who are insulin-dependent diabetics • Women using some anti-seizure medications • Women with medically diagnosed obesity • Women exposed to high temperatures early in pregnancy • It is more common in Caucasian and Hispanic women

28. Spina Bifida- How do you prevent it? • Folic acid!! • The recommended daily allowance is 400 micrograms • But it can be as much as 4000 micrograms in women at high-risk • Folic acid should be taken before conception through the third month of pregnancy • May reduce your risk by 70% • Half of all pregnancies are unplanned • All women of child bearing age should take a vitamin with folic acid!

29. Anencephaly • Occurs when the neural tube doesn’t close at the back of the skull • Without the complete skull, the brain fails to develop • These children are born with a brain stem, but no brain • Most survive only hours or days after birth

30. Anencephaly

31. Anencephaly

32. Cleft Lip and Palate • Occurs in 1 in every 700 births • The lip and palate form sometime around 6-12 weeks of pregnancy • Surgery is done to close the lip and palate • Children usually do very well with the surgery and develop normal speech • Some studies have shown that folic acid can also be useful in preventing cleft lip and palate • More common in children of Asian descent • Has many causes, some of which are genetic and not preventable

34. Cleft Lip and Palate

35. Cleft Lip and Palate Bilateral Unilateral

36. Cleft Lip: Before & After

37. Other multifactorial disorders • Asthma • Diabetes • Cardiovascular disease • Cancer

38. Effects of Genetics • Genes also play a role in how we develop • Some birth defects are due to changes in our genes • These cannot be predicted or prevented • Examples: • Down syndrome • Some heart defects • Sickle cell disease • Cystic fibrosis

39. What is a genetic condition? • Any condition caused by a change in a gene that leads to physical and/or mental differences • May present at birth or later in life • These gene-changes can happen by chance or can be inherited

40. Background on genetics • Every human being has about 30,000 genes that determine everything from eye color to the development of our physical and biochemical systems. • Genes come in pairs, and we inherit half of our genes from each parent. • Genes are packaged on 46 chromosomes inside our cells

41. Sperm = 23 Egg = 23 Fertilized egg = 46

43. Typical male 46 XY

44. Typical female 46 XX

45. Collecting cells for chromosome analysis • Blood • Tissue • Chorionic villi sampling (CVS) • Amniocentesis

46. Types of genetic diseases • Multifactorial disorders • Chromosomal disorders • Single gene disorders • Mitochondrial disorders

47. Chromosome disorders • Extra chromosome • Missing chromosome • Rearranged chromosomes • Extra or missing piece of chromosome

48. Down syndrome 47, +21

49. Down syndrome • Facial features similar to one another • Mental retardation • Heart problems • Intestinal problems • Vision and hearing problems • Number of other birth defects and health problems

50. Turner syndrome 45, XO