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Sex-linked dominant
Inheritance - sex-linked dominant; Genetics - sex-linked dominant; X-linked dominant; Y-linked dominant
Sex-linked dominant is a rare way that a trait or disorder can be passed down through families. One abnormal gene on the X chromosome can cause a sex-linked dominant disease.
Related terms and topics include:
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Autosomal dominant
Autosomal dominant
Autosomal dominant is one of several ways that a trait or disorder can be passed down (inherited) through families. In an autosomal dominant disease,...
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Autosomal recessive
Autosomal recessive
Autosomal recessive is one of several ways that a trait, disorder, or disease can be passed down through families. An autosomal recessive disorder me...
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Chromosome
Chromosome
Chromosomes are structures found in the center (nucleus) of cells that carry long pieces of DNA. DNA is the material that holds genes. It is the bu...
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Gene
Gene
A gene is a short piece of DNA. Genes tell the body how to build specific proteins. There are about 20,000 genes in each cell of the human body. T...
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Heredity and disease
Heredity and disease
Genetics is the study of heredity, the process of a parent passing certain genes to their children. A person's appearance -- height, hair color, ski...
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Inheritance
Inheritance
Genetics is the study of heredity, the process of a parent passing certain genes to their children. A person's appearance -- height, hair color, ski...
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Sex-linked recessive
Sex-linked recessive
Sex-linked diseases are passed down through families through one of the X or Y chromosomes. X and Y are sex chromosomes. Dominant inheritance occur...
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Information
Inheritance of a specific disease, condition, or trait depends on the type of chromosome that is affected. It can be either an autosomal chromosome or a sex chromosome. It also depends on whether the trait is dominant or recessive. Sex-linked diseases are inherited through one of the sex chromosomes, which are the X and Y chromosomes.
Dominant inheritance occurs when an abnormal gene from one parent can cause a disease, even though a matching gene from the other parent is normal. The abnormal gene dominates the gene pair.
For an X-linked dominant disorder: If the father carries the abnormal X gene, all of his daughters will inherit the disease and none of his sons will have the disease. That is because daughters always inherit their father's X chromosome. If the mother carries the abnormal X gene, half of all their children (daughters and sons) will inherit the disease tendency.
For example, if there are four children (two boys and two girls) and the mother is affected (she has one abnormal X and has the disease) but the father does not have the abnormal X gene, the expected odds are:
- Two children (one girl and one boy) will have the disease
- Two children (one girl and one boy) will not have the disease
If there are four children (two boys and two girls) and the father is affected (he has one abnormal X and has the disease) but the mother is not, the expected odds are:
- Two girls will have the disease
- Two boys will not have the disease
These odds do not mean that the children who inherit the abnormal X will show severe symptoms of the disease.
References
Feero WG, Zazove P, Chen F. Clinical genomics. In: Rakel RE, Rakel D, eds. Textbook of Family Medicine . 9th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 43.
Groden J, Gocha AS, Croce CM. Human basic genetics and patterns of inheritance. In: Creasy RK, Resnik R, Iams JD, Lockwood CJ, Moore TR, Greene MF, eds. Creasy and Resnik's Maternal-Fetal Medicine: Principles and Practice . 7th ed. Philadelphia, PA: Elsevier Saunders; 2014:chap 1.
Korf BR. Principles of genetics. In: Goldman L, Schafer AI, eds. Goldman's Cecil Medicine . 25th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 40.
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Genetics - illustration
Genetics is the study of heredity and how traits are passed along from parents to offspring. Genes are contained within the chromosomes found within the egg and sperm. Each parent contributes one half of each pair or 23 chromosomes to their child, 22 autosomal and 1 sex chromosome. The inheritance of genetic diseases, abnormalities, or traits is described by both the type of chromosome the abnormal gene resides on (autosomal or sex chromosome), and by whether the gene itself is dominant or recessive.
Genetics
illustration
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Genetics - illustration
Genetics is the study of heredity and how traits are passed along from parents to offspring. Genes are contained within the chromosomes found within the egg and sperm. Each parent contributes one half of each pair or 23 chromosomes to their child, 22 autosomal and 1 sex chromosome. The inheritance of genetic diseases, abnormalities, or traits is described by both the type of chromosome the abnormal gene resides on (autosomal or sex chromosome), and by whether the gene itself is dominant or recessive.
Genetics
illustration
Review Date: 1/25/2016
Reviewed By: Chad Haldeman-Englert, MD, FACMG, Fullerton Genetics Center, Asheville, NC. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.
