URL of this page: https://medlineplus.gov/genetics/understanding/inheritance/riskassessment/
When a genetic disorder is diagnosed in a family, family members often want to know the likelihood that they or their children will develop the condition. This can be difficult to predict in some cases because many factors influence a person's chances of developing a genetic condition. One important factor is how the condition is inherited. For example: Autosomal dominant inheritance: A person affected by an autosomal dominant disorder Autosomal recessive inheritance: Two unaffected people who each carry one copy of the altered gene for an autosomal recessive disorder (carriers) have a 25 percent chance with each pregnancy of having a child affected by the disorder. The chance with each pregnancy of having an unaffected child who is a carrier of the disorder is 50 percent, and the chance that a child will not have the disorder and will not be a carrier is 25 percent. If only one parent is a carrier of the altered gene and the other parent does not carry the variant, none of their children will develop the condition, and the chance with each pregnancy of having an unaffected child who is a carrier is 50 percent.X-linked dominant inheritance: The chance of passing on an X-linked dominant condition differs between men and women because men have one X chromosome and one Y chromosome, while women have two X chromosomes. A man passes on his Y chromosome to all of his sons and his X chromosome to all of his daughters. Therefore, the sons of a man with an X-linked dominant disorder will not be affected, but all of his daughters will inherit the condition. A woman passes on one or the other of her X chromosomes to each child. Therefore, a woman with an X-linked dominant disorder has a 50 percent chance of having an affected daughter or son with each pregnancy.X-linked recessive inheritance: Because of the difference in sex chromosomes, the probability of passing on an X-linked recessive disorder also differs between men and women. The sons of a man with an X-linked recessive disorder will not be affected, and his daughters will carry one copy of the altered gene. With each pregnancy, a woman who carries an altered gene for X-linked recessive has a 50 percent chance of having sons who are affected and a 50 percent chance of having daughters who carry one copy of the altered gene. Females with one gene variant associated with an X-linked recessive disorder typically have no or very mild signs or symptoms of the condition.X-linked: Because the inheritance pattern of many X-linked disorders is not clearly dominant or recessive, some experts suggest that conditions be considered X-linked rather than X-linked dominant or X-linked recessive. As above, the probability of passing on an X-linked disorder differs between men and women. The sons of a man with an X-linked disorder will not be affected, but all of his daughters will inherit the altered gene and may develop signs and symptoms of the condition. A woman passes on one or the other of her X chromosomes to each child. Therefore, with each pregnancy, a woman with an X-linked disorder has a 50 percent chance of having a child with the altered gene. An affected daughter may have milder signs and symptoms than an affected son. Y-linked inheritance: Because only males have a Y chromosome, only males can be affected by and pass on Y-linked disorders . All sons of a man with a Y-linked disorder will inherit the condition from their father.Codominant inheritance: In codominant inheritance , each parent contributes a different version of a particular gene, and both versions influence the resulting genetic trait. The chance of developing a genetic condition with codominant inheritance, and the characteristic features of that condition, depend on which versions of the gene are passed from parents to their child.Mitochondrial inheritance: Mitochondria, which are the energy-producing centers inside cells, each contain a small amount of DNA. Disorders with mitochondrial inheritance result from variants in mitochondrial DNA. Although these disorders can affect both males and females, only females can pass variants in mitochondrial DNA to their children. A woman with a disorder caused by changes in mitochondrial DNA will pass the variants to all of her daughters and sons, but the children of a man with such a disorder will not inherit the variant.It is important to note that the chance of passing on a genetic condition applies equally to each pregnancy. For example, if a couple has a child with an autosomal recessive disorder, the chance of having another child with the disorder is still 25 percent (or 1 in 4). Having one child with a disorder does not “protect” future children from inheriting the condition. Conversely, having a child without the condition does not mean that future children will definitely be affected. Although the chances of inheriting a genetic condition appear straightforward, factors such as a person's family history and the results of genetic testing can sometimes modify those chances. In addition, some people with a disease-causing variant never develop any health problems or may experience only mild symptoms of the disorder. If a disease that runs in a family does not have a clear-cut inheritance pattern, predicting the likelihood that a person will develop the condition can be particularly difficult. Estimating the chance of developing or passing on a genetic disorder can be complex. Genetics professionals can help people understand these chances and help them make informed decisions about their health. Learn how to cite this page Feero WG, Zazove P, Chen F. Clinical genomics. In: Rakel RE, Rakel DP, eds. Textbook of Family Medicine. 9th ed. Philadelphia, PA: Elsevier; 2016:chap 43. Gregg AR, Kuller JA. Human genetics and patterns of inheritance. In: Resnik R, Lockwood CJ, Moore TR, Greene MF, Copel JA, Silver RM, eds. Creasy and Resnik's Maternal-Fetal Medicine: Principles and Practice. 8th ed. Philadelphia, PA: Elsevier; 2019:chap 1. Jones KL, Jones MC, Campo M. Genetics, genetic counseling, and prevention. In: Jones KL, Jones MC, Campo MD, eds. Smith's Recognizable Patterns of Human Deformation. 8th ed. Philadelphia, PA: Elsevier; 2022:chap 2. Korf BR. Principles of genetics. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 26th ed. Philadelphia, PA: Elsevier; 2020:chap 35. Page 2Updated by: Linda J. Vorvick, MD, Clinical Associate Professor, Department of Family Medicine, UW Medicine, School of Medicine, University of Washington, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team. Page 3Updated by: Linda J. Vorvick, MD, Clinical Associate Professor, Department of Family Medicine, UW Medicine, School of Medicine, University of Washington, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team. Page 4National Academy of Sciences, Institute of Medicine, Food and Nutrition Board. Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids. National Academy Press. Washington, DC, 2005. nap.nationalacademies.org/catalog/10490/dietary-reference-intakes-for-energy-carbohydrate-fiber-fat-fatty-acids-cholesterol-protein-and-amino-acids. Ramu A, Neild P. Diet and nutrition. In: Naish J, Syndercombe Court D, eds. Medical Sciences. 3rd ed. Philadelphia, PA: Elsevier; 2019:chap 16. US Department of Health and Human Services and US Department of Agriculture. 2015-2020 Dietary Guidelines for Americans. 8th ed. health.gov/dietaryguidelines/2015/resources/2015-2020_Dietary_Guidelines.pdf. Updated December 2015. Accessed August 16, 2021. Page 5USING MyPlate There are 5 major food groups that make up a healthy diet:
You should eat foods from each group every day. How much food you should eat from each group depends on your age, sex, and how active you are. MyPlate makes specific recommendations for each type of food group. GRAINS: MAKE AT LEAST HALF OF YOUR GRAINS WHOLE GRAINS
Most children and adults should eat about 5 to 8 servings of grains a day (also called "ounce equivalents"). Children age 8 and younger need about 3 to 5 servings. At least half those servings should be whole grain. An example of one serving of grains includes:
Eating whole grains can help improve your health by:
Ways to eat more whole grains:
VEGETABLES: MAKE HALF OF YOUR PLATE FRUITS AND VEGETABLES
Most children and adults should eat between 2 and 3 cups (200 to 300 grams) of vegetables a day. Children age 8 need about 1 to 1 1/2 cups (100 to 150 grams). Examples of a cup include:
Eating vegetables can help improve your health in the following ways:
Ways to eat more vegetables:
FRUITS: MAKE HALF OF YOUR PLATE FRUITS AND VEGETABLES
Most adults need 1 1/2 to 2 cups (200 to 250 grams) of fruit a day. Children age 8 and younger need about 1 to 1 1/2 cups (120 to 200 grams). Examples of a cup include:
Eating fruit can help improve your health, they may help to:
Ways to eat more fruit:
PROTEIN FOODS: CHOOSE LEAN PROTEINS Protein foods include meat, poultry, seafood, beans and peas, eggs, processed soy products, nuts and nut butters, and seeds. Beans and peas are also part of the vegetable group.
Examples of a serving include:
Eating lean protein can help improve your health:
Ways to include more lean protein in your diet:
DAIRY: CHOOSE LOW-FAT OR FAT-FREE DAIRY FOODS Most children and adults should get about 3 cups (720 milliliters) of dairy a day. Children age 2 to 8 need about 2 to 2 1/2 cups (480 to 600 milliliters). Examples of a cup include:
Eating dairy food can improve your health:
Ways to include low-fat foods from the dairy group in your diet:
OILS: EAT SMALL AMOUNTS OF HEART-HEALTHY OILS
WEIGHT MANAGEMENT AND PHYSICAL ACTIVITY MyPlate also provides information about how to lose excess weight:
You can also learn how to make better choices, such as:
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