Pedigree and Probability Calculations

Some health problems are passed down through families. There are different ways this can happen. To have a child born with what’s called an “autosomal recessive disease” like sickle cell disease or cystic fibrosis, both you and your partner must have a mutated (changed) gene that you pass on to your child. How Are People Affected? Almost every cell in your body contains 23 pairs of tightly wound DNA called chromosomes. You get 23 of them from your mother and 23 from your father. One pair of chromosomes decides your sex. The others contain thousands of different genes that decide every other trait you have, from hair and eye color to your risk of getting diseases. These are called autosomes. Some genes are “dominant.” You only need one from a parent to have that trait. Other genes are “recessive.” With them, you have to inherit the same gene from both parents to be affected. If one of your parents passes on a recessive gene to you that can cause disease, then you become a “carrier.” You likely won’t have any symptoms, since the other gene is normal. In fact, many people won’t know they’re a carrier without being tested. But if you and your partner both have the same mutated gene, there’s a 25% chance that your child will be born with a severe disease. Anyone can carry a recessive gene that causes illness, but some diseases are more common in certain ethnic groups. What Are Some Types of These Diseases? Common autosomal recessive disorders include: Sickle cell disease: About 1 in 12 African-American people are carriers of this disease. One in 500 African-American babies is born with it. Sickle cell causes your red blood cells to be stiff and sticky so they can’t easily move oxygen through your body. This puts you at risk for painful complications and severe infections. Cystic fibrosis (CF): People with this disorder produce very thick mucus that sticks to their lungs and harms major organs. CF also makes it hard for your body to digest and absorb food. Tay-Sachs disease: This causes intense damage to the central nervous system. It occurs most often in people whose ancestors are Ashkenazi Jews, French Canadian, Amish, or Cajun. Gaucher disease: Many of your organs and tissues can be damaged from this disease. An enlarged liver and spleen, as well as anemia, are common. Some people also have seizures and brain damage. The most severe type causes problems for babies before they’re born or in the days right after birth. Many autosomal recessive diseases will have a severe effect on the life of a child. In some cases, they may be fatal. Who Should Be Tested, and When? Screening for many autosomal recessive diseases is available. You may get tested if you have high odds of being a carrier of the disease, or if you just want to know the risk of having a child with one of these diseases. A DNA test can check to see if you and your partner carry any of the mutated genes that may cause your child to have a disease. This can be done by taking a blood sample or gently scraping cells from the inside of your mouth. If you’re already pregnant, the health of your baby can be checked. Outpatient procedures such as amniocentesis and chorionic villus sampling (CVS) check fluid or tissue from your uterus to see if your baby shows signs of one of these diseases. Newborns can also be screened for severe autosomal recessive disorders soon after birth. What If the Results Are Positive? If your results show that you could pass on an autosomal recessive disease to your baby, you may want to speak to a genetic counselor. This is someone who’s trained to know about medical problems that run in families. They can help you make sense of your test results and figure out what to do next. A genetic counselor can also help if your baby is born with an autosomal recessive disorder. They’ll be able to give you information, find doctors who can help treat your baby’s condition, and connect you with support groups. It may help you to talk with other parents whose child has the same health issue. #tickleCellAnemia #pedigree #geneticDisorder #disease #Gene #allele #PedigreeAnalysis #pedigreeAnalysisPractice #pedigreeAnalysisGenetics #pedigreeAnalysisProbability #pedigreeAnalysisAnswers #pedigreeCharts #Genetics #HowToSolvePedigreeProblems #solvePedigreeProblems #solvingPedigreeProblems #pedigreeProblemsAndSolutions #howToAnalyzePedigree #analyzingPedigree #geneticsProblems