Part 2: Autosomal Dominant Trait

5. Males transmit their Y chromosome to their sons. This means that sons will not inherit an X-linked recessive condition from their father.

The likelihood of close relatives sharing the same recessive alleles is greater than in the general population, raising the risks that a child would be homozygous recessive for a trait.

1. What is the likelihood that any of their children (sons and/or daughters) will be born with the disorder?

Autosomal recessive inheritance is the third type known to cause muscular dystrophy, whereas both parents are carriers of the defective gene. For this reason the offspring have a 25% chance of being affected with both malformed genes, resulting in them being affected. The chance increases with cousin marriages.

b. How is it caused on a genetic level? Be specific about the chromosome #, genetic mutation, dominant or recessive, and chance of inheriting the disorder.

Consanguineous means people coming from the same heritage. This is especially important when discussing recessive genetic disorders because it could affect the chances of someone occupying the disease.

This disease is genetically inherited and is a dominant characteristic, therefore unfortunately the offspring of a victim has 50% chance of inheriting the disease.

had occurred in members of 2 sibships related as first cousins once removed. Although autosomal recessive

Introduction: The gene that codes for red-green color blindness, the most common form of color blindness in humans, is found on the X chromosome. One in 12 males is color blind. In females, however, color blindness affects only about 1 in 200. Why is

Researchers identified that a gene in the X chromosome that when flawed it is the cause of MD. Dystrophin is the gene that is needed in the X chromosome to have fully functioning muscle development. MD is inherited in only the X chromosome so males have a 50% chance of inheriting the condition if the mother is a carrier, but females have a very low risk because they get an X chromosome from both mother and father. This condition is an X-linked recessive pattern. If a female inherits a mutated dystrophin gene from one of her parents, she will usually get a healthy dystrophin gene from her other parent because the father can pass the recessive gene in the X chromosomes. The female becomes a carrier just like her mother because the mutation is still in her genes . A male who mother who’s is a carrier has a 50% chance of inheriting the mutation and if they do inherit the gene they will develop the disease because they can not rely on

Autosomal recessive inheritance implies that the quality is situated on a single autosome of the autosomes. This implies men and women are similarly influenced. "Recessive" implies that two duplicates of the gene are important to have the characteristic, one acquired from each parent. An individual who has only a single recessive gene is know a "carrier" for this gene or infection, yet they don't have any medical issues from "carrying" one duplicate of the gene. Majority of the individual are not aware that they are carry a heterozygous genetic factor for an illness until they have a baby with it. [1] When mother and father have had a child with a recessive trait or illness, there is a one out of four, or 25% chance, with each consequent pregnancy,

The first generations are skipped, although Nicolas (1904-18) was a hemophiliac, neither his parents nor grandparents were. This pattern occurs in several other places of the pedigree, and indicates a recessive mode of inheritance. From the biochemical nature of the defect, scientists have determined that hemophilia is a recessive trait. All the affected individuals are sons, strongly suggesting that the defect is a sex linkage trait. Since males are hemizygous for the X chromosome, more males than females should have the phenotype of

Albinism is a recessive inherited defect in melanin metabolism in which pigment is absent from the hair, skin, and eyes (oculocutaneous albinism) or just from the eyes (ocular Albinism). Albinos tend to be children of parents who were first cousins.

X-linked recessive means that the gene causing the trait or disorder is located on the X chromosome but can be overpowered by a dominant trait. In females there is two X chromosomes one from their mother and one from their father; males have one X and one Y, the X is from their mother and the Y from their father. X linked recessive genes are expressed differently in males and females. X-linked recessive genes emerge in females only if there are two copies of the gene (one on each X chromosome). However, in males, there needs to be only one copy of an X-linked recessive gene in order for the trait or disorder to be

The same principles used to explore Dianne’s family pedigree can be applied to Jacks. As Jack’s brother has the disorder, it is safe to assume that either his father or mother has the disorder. As Jack’s father is unaffected it can be seen that the disorder did not come from him, but rather it came from Jack’s mother. Because of this, there is a 25% chance that his parents would have a boy with the disorder, 25% chance they will have a boy with no problems, a 25% chance that they will have a girl who is a carrier, and another 25% chance they will have a girl that is unaffected. As males either have the disorder or they don’t, it is clear that Jack does not have Duchenne muscular dystrophy. Because of this it is safe to say that Jack was part of the 25% of boys that do not have the disorder.