What is the evolutionary process of Tay-Sachs disease?
Tay-Sachs disease is inherited in an autosomal recessive manner. This means that to have the disease, a person must have a mutation in both copies of the responsible gene in each cell . There is nothing either parent can do, before or during a pregnancy, to cause a child to have Tay-Sachs disease.
What is affected in Tay-Sachs disease?
Tay-Sachs disease is a rare disorder passed from parents to child. It’s caused by the absence of an enzyme that helps break down fatty substances. These fatty substances, called gangliosides, build up to toxic levels in the child’s brain and affect the function of the nerve cells.
Why does Tay-Sachs protect against tuberculosis?
The protection against TB that Tay-Sachs disease heterozygosity apparently offered remained among the Jewish people because they were prevented from leaving the ghettos. The mutant allele increased in frequency as TB selectively felled those who did not carry it and the carriers had children with each other.
What gene controls Tay-Sachs?
Variants in the HEXA gene cause Tay-Sachs disease. The HEXA gene provides instructions for making one part (the alpha subunit) of an enzyme called beta-hexosaminidase A.
Is Tay-Sachs disease dominant or recessive?
Tay-Sachs disease is inherited as an autosomal recessive disease. Recessive genetic disorders occur when an individual inherits two copies of an abnormal gene, one from each parent.
Is Tay-Sachs homozygous or heterozygous?
Tay–Sachs disease (TSD) and late-onset Tay–Sachs (LOTS) are inherited as autosomal recessive disorders. Homozygous individuals are uniformly affected, while heterozygous carriers have no disease manifestations.
How does Krabbe disease affect the body?
Krabbe (KRAH-buh) disease is an inherited disorder that destroys the protective coating (myelin) of nerve cells in the brain and throughout the nervous system. In most cases, signs and symptoms of Krabbe disease develop in babies before 6 months of age, and the disease usually results in death by age 2.
Which type of mutation is responsible for causing Tay-Sachs disease Brainly?
Tay-Sachs disease is caused by mutations in the HEXA gene . The HEXA gene provides instructions for making part of an enzyme called beta-hexosaminidase A, which plays a critical role in the brain and spinal cord.
Why does Tay-Sachs disease persist?
Tay-Sachs is caused by the absence of a vital enzyme called hexosaminidase-A (Hex-A). Without Hex-A, a fatty substance, or lipid, called GM2 ganglioside accumulates abnormally in cells, especially in the nerve cells of the brain. This ongoing accumulation causes progressive damage to the cells.
What is the link between Tay-Sachs allele and tuberculosis?
Tay-Sachs disease and resistance to tuberculosis Although controversial, it has been hypothesized that perpetuation of this allele is associated with the selective advantage it provides protection against Mycobacteria tuberculosis, the causative agent for the highly infectious disease tuberculosis.
What type of mutation causes Tay-Sachs?
Tay-Sachs disease is caused by a change (mutation) in the hexosaminidase subunit alpha (HEXA) gene. Genes provide the instructions for the basic structure of proteins, all of which that play a critical role in many functions and structure of the body.
Is Tay-Sachs a gene or chromosome mutation?
Tay-Sachs disease is an autosomal recessive condition. Sex-linked conditions are caused by genes located on a sex chromosome (X or Y). Tay-Sachs disease is caused by a gene (HEXA) located on chromosome 15, an autosome .
What kind of disease is Tay Sachs disease?
Tay-Sachs disease is a rare, inherited neurodegenerative disease. People with Tay-Sachs disease do not have enough of an enzyme called beta-hexosaminidase A. The less enzyme a person has, the more severe the disease and the earlier that symptoms appear. There are 3 forms of Tay-Sachs disease, distinguished by the general age of onset: [1] [2]
How are blood tests used to diagnose Tay Sachs?
To diagnose Tay-Sachs disease, healthcare providers do a blood test. They measure the level of hexosaminidase A in the body. In a child with classic Tay-Sachs, this protein is mostly or completely missing. People with other forms of the disease have reduced levels.
What causes muscle weakness in babies with Tay Sachs?
Babies with Tay-Sachs lack a particular enzyme, which is a protein that triggers chemical reactions in cells. The lack of the enzyme, hexosaminidase A, causes a fatty substance to collect. The buildup of this substance, GM2 ganglioside, leads to Tay-Sachs symptoms such as muscle weakness. Tay-Sachs is a genetic condition.
Is the allele for Tay Sachs on the X chromosome?
Explain one piece of evidence from the diagram which proves that the allele for Tay-Sachs disease is not on the X chromosome. (2) In a human population, one in every 1000 children born had Tay-Sachs disease. Use the Hardy-Weinberg equation to calculate the percentage of this population you would expect to be heterozygous for this gene.