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A hereditary carrier (genetic carrier or just carrier), is a person or other organism that has inherited a recessive allele for a genetic trait or mutation but usually does not display that trait or show symptoms of the disease. Carriers are, however, able to pass the allele onto their offspring, who may then express the genetic trait.
Asymptomatic carriers can be categorized by their current disease state. [5] When an individual transmits pathogens immediately following infection but prior to developing symptoms, they are known as an incubatory carrier. Humans are also capable of spreading disease following a period of illness.
Females with this disease are almost exclusively unaffected, obligate carriers. The mutations can be passed on to offspring by mothers and fathers, but the phenotype is only expressed in males that inherit the mutation. [7] All daughters of a hemophiliac father are obligate carriers of the disease.
Disease carrier could refer to: Asymptomatic carrier , a person or organism infected with an infectious disease agent, but displays no symptoms Genetic carrier , a person or organism that has inherited a genetic trait or mutation, but displays no symptoms
X-linked recessive inheritance. X-linked recessive inheritance is a mode of inheritance in which a mutation in a gene on the X chromosome causes the phenotype to be always expressed in males (who are necessarily hemizygous for the gene mutation because they have one X and one Y chromosome) and in females who are homozygous for the gene mutation, see zygosity.
When the father alone is the carrier of a defective gene associated with a disease or disorder, he too will have the disorder. His children will inherit the disorder as follows: Of his daughters: 100% will have the disorder, since all of his daughters will receive one copy of his single X chromosome.
Koch's postulates of disease. Koch's four postulates are: [5] The microorganism must be found in abundance in all organisms suffering from the disease but should not be found in healthy organisms. The microorganism must be isolated from a diseased organism and grown in pure culture.
[13] [15] [16] Penetrance can also be age-dependent, meaning signs or symptoms of disease are not visible until later in life. For example, Huntington disease is an autosomal dominant condition, but up to 25% of individuals with the affected genotype will not develop symptoms until after age 50. [ 17 ]