Bart syndrome
Encyclopedia
Bart syndrome is a genetic disorder
characterized by the association of congenital localized absence of skin
, epidermolysis bullosa
, lesions of the mouth mucosa, and dystrophic nails.
but variable expression
. This means that children of an affected parent that carries the gene have a 50% chance of developing the disorder, although the extent to which they are affected is variable.
Bart syndrome is caused by ultrastructural abnormalities in the anchoring fibrils
. Genetic linkage of the inheritance of the disease points to the region of chromosome 3 near the collagen, type VII, alpha 1 gene (COL7A1
).
Genetic disorder
A genetic disorder is an illness caused by abnormalities in genes or chromosomes, especially a condition that is present from before birth. Most genetic disorders are quite rare and affect one person in every several thousands or millions....
characterized by the association of congenital localized absence of skin
Skin
-Dermis:The dermis is the layer of skin beneath the epidermis that consists of connective tissue and cushions the body from stress and strain. The dermis is tightly connected to the epidermis by a basement membrane. It also harbors many Mechanoreceptors that provide the sense of touch and heat...
, epidermolysis bullosa
Epidermolysis bullosa
Epidermolysis bullosa is an inherited connective tissue disease causing blisters in the skin and mucosal membranes, with an incidence of 1/50,000. Its severity ranges from mild to lethal. It is caused by a mutation in the keratin or collagen gene....
, lesions of the mouth mucosa, and dystrophic nails.
Genetics
The disease is inherited by autosomal dominant transmission with complete penetrancePenetrance
Penetrance in genetics is the proportion of individuals carrying a particular variant of a gene that also express an associated trait . In medical genetics, the penetrance of a disease-causing mutation is the proportion of individuals with the mutation who exhibit clinical symptoms...
but variable expression
Expressivity
Expressivity is a term used in genetics to refer to variations in a phenotype among individuals carrying a particular genotype. The term can be used to characterize qualitatively or quantitatively the extent of phenotypic variation given a particular genotype. The term is analogous to the...
. This means that children of an affected parent that carries the gene have a 50% chance of developing the disorder, although the extent to which they are affected is variable.
Bart syndrome is caused by ultrastructural abnormalities in the anchoring fibrils
Anchoring fibrils
Anchoring fibrils extend from the basal lamina of epithelial cells and attach to the lamina reticularis by wrapping around the reticular fiber bundles. The basal lamina and lamina reticularis together make up the basement membrane...
. Genetic linkage of the inheritance of the disease points to the region of chromosome 3 near the collagen, type VII, alpha 1 gene (COL7A1
COL7A1
Collagen alpha-1 chain is a protein that in humans is encoded by the COL7A1 gene.- Function :This gene encodes the alpha chain of type VII collagen. The type VII collagen fibril, composed of three identical alpha collagen chains, is restricted to the basement zone beneath stratified squamous...
).