Anderson-Fabry disease is a rare genetic pathology that is part of a group of ailments known as lysosomal storage disorders caused by alterations (mutations) of the alpha galactosidase gene. These alterations cause a reduction in the production of an enzyme called alpha-galactosidase A.
People with Fabry disease have a lack, dysfunction, or total congenital absence of alpha-galactosidase A. As a result, a fatty substance (a lipid called ceramide trihexoside (CTH), also known as globotriaosylceramide), that in another way would be decomposed by this enzyme accumulates in the cells lysosomes. Over time this accumulation causes damage to the cells, tissues and walls of the blood vessels, causing the onset of the symptoms of the disease.
If left untreated, vital organs such as the kidneys, heart and brain eventually begin to deteriorate and serious, sometimes life-threatening, complications can arise.
Fabry disease occurs in two types: the classic form, with early symptoms and involvement of multiple organs, and the late onset form, which mainly affects only one organ. However, there are also intermediate and atypical cases.
Who Can Get Fabry Disease?
It has been estimated that Fabry disease affects one of 40,000 to 120,000 newborns of both sexes and all ethnicities. The symptoms of the classic form may begin in childhood, although most appear during adolescence or in young adults.
How is Fabry Disease Inherited?
The gene responsible for Fabry disease is located on the X chromosome -one of the two chromosomes that determine the sex of an individual- and it is transmitted from one of the parents (the carrier) to their children. This means that there are differences between the way in which Fabry disease affects men and women, and also in the way it is transmitted to their children.
Men only have one X chromosome. So, if this chromosome contains the defective gene linked to Fabry’s disease, will have a very high probability of developing the symptoms of Fabry disease. Because of the way in which Fabry disease is inherited, men cannot transmit this disease to their sons. However, all of their daughters will have a copy of the defective gene.
Women have two X chromosomes; only one of them can have a copy of the defective gene. The symptoms in women can be variable, from extremely mild to as severe as in men, but their symptoms usually appear at a later age than in men.
Women with Fabry disease have a 50 percent chance of transmitting the defective gene to their children, regardless of they are boys or girls.
Genes: Transmitters of characters to Offspring
Nowadays we know that the characters are transmitted thanks to genes. A gene is a segment of DNA that encodes a protein.
The characters that are expressed in an individual depend on their genes. Sometimes a character depends on a single gene and in other cases it depends on several genes acting together.
Is Fabry Disease a Dominant or Recessive Trait?
A gene can have several alternative forms (called alleles), each one with a different DNA sequence and expressing the same trait differently.
An example of this is found in the color of the eyes. In humans, the color of the eyes depends on several genes and each one of them has several alleles. The color of a person’s eyes will depend on the combination of alleles of the genes involved in that trait.
Some of these alleles express themselves with greater “intensity” than others, masking their presence. For example, the allele of brown eyes masks that of blue eyes. The genes that are expressed with greater intensity are called dominant genes, while those that are not expressed in the presence of a dominant allele are considered recessive alleles or recessive genes.
Fabry disease is inherited recessively linked to the X chromosome, which means that the gene that causes the disease is on the X chromosome. In men (who only have one X chromosome) one copy of the mutated gene is enough to cause the symptoms. Because women have two copies of the X chromosome in their cells, one copy of the mutated gene usually produces less severe or does not cause any symptoms.
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