890 likes | 1.31k Views
Genetic Conditions and Birth Defects. Camila Vieira Shanahan, MS, CGC Genetic Counselor Fullerton Genetics Center February 17, 2012. Outline. Prenatal Exposures Types of Genetic Conditions Multifactorial disorders Chromosomal disorders Single gene disorders Mitochondrial disorders
E N D
Genetic Conditions and Birth Defects Camila Vieira Shanahan, MS, CGC Genetic Counselor Fullerton Genetics Center February 17, 2012
Outline • Prenatal Exposures • Types of Genetic Conditions • Multifactorial disorders • Chromosomal disorders • Single gene disorders • Mitochondrial disorders • Genetics Clinic
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.
With every pregnancy, the chance for a baby to be born with a birth defect is… 3-5%
Maintaining a healthy lifestyle is important during pregnancy
Which of the following can cause more harm to a fetus? • Cigarettes • Crack/Cocaine • Heroin • Alcohol
“Alcohol causes more damage to the developing fetus than any other substance, including marijuana, heroin, and cocaine.” Institute of Medicine, 1996
Effects of Alcohol • Consumption of alcohol during pregnancy can have devastating effects on the baby • No amount of alcohol is okay
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
Characteristic FAS Facial Features Source: www. niaaa.nih.gov/ Source: www.come-over.to/FASCRC/
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
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
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
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
Pregnancy Exposure ProgramFullerton Genetics Center (800) 532-6302
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
Types of genetic diseases • Multifactorial disorders • Chromosomal disorders • Single gene disorders • Mitochondrial disorders
Multifactorial Disorders • No clear inheritance pattern • Recurrence risk difficult to estimate • Combination of genetic and environmental factors
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
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
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
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
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!
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
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
Cleft Lip and Palate Bilateral Unilateral
Other multifactorial disorders • Asthma • Diabetes • Cardiovascular disease • Cancer
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
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
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
Sperm = 23 Egg = 23 Fertilized egg = 46
Collecting cells for chromosome analysis • Blood • Tissue • Chorionic villi sampling (CVS) • Amniocentesis
Types of genetic diseases • Multifactorial disorders • Chromosomal disorders • Single gene disorders • Mitochondrial disorders
Chromosome disorders • Extra chromosome • Missing chromosome • Rearranged chromosomes • Extra or missing piece of chromosome
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