Where is the dystrophin gene located?
The dystrophin gene is the largest gene yet identified in humans and is located in the short arm of the X chromosome, in the Xp21. 2 locus (a locus is the position of a gene on a chromosome).
What chromosome is DMD located on?
DMD is caused by mutations of the DMD gene located on the short arm (p) of the X chromosome (Xp21. 2). Chromosomes, which are present in the nucleus of human cells, carry the genetic information for each individual.
Why can’t girls get muscular dystrophy?
Because boys only have only one X-chromosome (and one Y-chromosome), they will have Duchenne if there is a mutation in the dystrophin gene. However, girls have TWO X-chromosomes, which means they have TWO dystrophin genes.
What happens to dystrophin in muscular dystrophy?
Mutations in the DMD gene alter the structure or function of dystrophin or prevent any functional dystrophin from being produced. Muscle cells without enough of this protein become damaged as muscles repeatedly contract and relax with use.
What causes MD?
In most cases, muscular dystrophy (MD) runs in families. It usually develops after inheriting a faulty gene from one or both parents. MD is caused by mutations (alterations) in the genes responsible for healthy muscle structure and function.
Can a girl have DMD?
Duchenne muscular dystrophy usually affects males. However, females are also affected in rare instances. Approximately 8% of female Duchenne muscular dystrophy (DMD) carriers are manifesting carriers and have muscle weakness to some extent.
What is dystrophin made of?
Dystrophin-glycoprotein complex (DGC). Dystrophin is a rod shape protein that links intracellular cytoskeleton network to transmembrane components of the DGC, including dystroglycan, sarcoglycans and sarcospan. Dystroglycan is composed of two subunits, α and β.
What is the role of dystrophin in the motor unit?
Dystrophin is a protein found in muscle cells. It is one of a group of proteins that work together to strengthen muscle fibers and protect them from injury as muscles contract and relax.
What is the structure of dystrophin?
Dystrophin is a rod shape protein that links intracellular cytoskeleton network to transmembrane components of the DGC, including dystroglycan, sarcoglycans and sarcospan. Dystroglycan is composed of two subunits, α and β.
How is the X chromosome related to hemophilia?
The X chromosome contains many genes that are not present on the Y chromosome. This means that males only have one copy of most of the genes on the X chromosome, whereas females have 2 copies. Thus, males can have a disease like hemophilia if they inherit an affected X chromosome that has a mutation in either the factor VIII or factor IX gene.
How is the gene for hemophilia passed down?
The mutation causes the body to produce too little factor VIII or IX. This change in a copy of the gene making factor VIII or factor IX is called a hemophilia allele. Most people who have hemophilia are born with it. It almost always is inherited (passed down) from a parent to a child.
How is the F8 gene related to hemophilia B?
Changes in the F8 gene are responsible for hemophilia A, while mutations in the F9 gene cause hemophilia B. The F8 gene provides instructions for making a protein called coagulation factor VIII. A related protein, coagulation factor IX, is produced from the F9 gene. Coagulation factors are proteins that work together in the blood clotting process.
Are there inherited mutations that cause mild hemophilia?
The mutations responsible for mild and moderate hemophilia reduce but do not eliminate the activity of one of these proteins. Another form of the disorder, known as acquired hemophilia, is not caused by inherited gene mutations.