chromosome 4 has the genetic mutation for huntington's disease.
chromosome 4 has the genetic mutation for huntington's disease.
what chromosome has the genetic mutation for huntington's disease?
chromosome 4
the mutation in collagen type 1 (col1 a1, col1 a2) causes di-1. it is similar to the systemic condition dental features known as osteogenesis imperfect. di-2, di-3 and dd-2 share the same genetic mutation of dentin sialophosphoprotein, that is located on chromosome 4. they are autosomal-dominant diseases with complete penetrance and variable expressivity. due to the same genetic mutation, these diseases would often result in overlapping clinical and radiographic features. therefore, prevailing theories suggests that di-2, di-3 and dd-2 are categorized as a single disease entity with variable severity of expression. however, the causes of dd-1 have yet to be theorized.
dentin dysplasia
the sex-linked x chromosome disorder manifests almost exclusively in males, even though the genetic mutation causing the disorder is located on the x chromosome and can be inherited from the mother by male children or from either mother or father by female children. this is because the trait is recessive, meaning that only one correctly-functioning copy of the blood clotting factor gene is necessary for normal clotting. females have two x chromosomes, and hence redundant copies of the blood clotting factor gene located on them. a female who inherits a mutated copy on one x chromosome has also inherited a second x chromosome from the other parent that is likely to carry a non-mutated copy of the gene, capable of directing appropriate clotting. such a female, with normal clotting but possessing a single mutated copy of the gene, is called a carrier. males only possess a single x chromosome, inherited from their mother, having received a y chromosome from their father instead of a second x. if their sole x chromosome contains the haemophilia mutation they possess no second copy to provide for normal function, as in carrier females. each child of a carrier will have a 50% chance of inheriting their mother's mutation, of being a haemophiliac (sons) or carrier (daughters). the daughter of a male haemophiliac will always inherit his mutation, while a son cannot ever inherit it. a female will only be affected with haemophilia in the rare circumstance that she inherits mutated x chromosomes from both a haemophiliac father and a carrier mother. no case of such double inheritance is known among queen victoria's descendants.
haemophilia in european royalty