19 April 2010
Maple Syrup Urine Disease
I. General Information
-Maple Syrup Urine disease is an inherited disorder in which the body does not and is unable to process certain protein building block called amino acids leucine, isoleucine, and valine. -To treat this disease the infected would have to have a protein-free diet. Fluids, sugars and possibly fats are given through a vein (IV). II. Nature of this Mutation
-Symptoms of this mutation include avoiding food, coma, feeding difficulties, lethargy, seizures, urine that smells like maple syrup, vomiting. -The nature of this mutation is more of a point mutation in the BCKDHA, BCKDHB, DBT, and DLD genes. These genes have the instructions for the making of proteins, and so if a mutation (addition, deletion, substitution) occurs the result will eliminate the function of the protein complex, preventing normal breakdown of amino acids. III. How it is related to Meiosis and Fertilization
-“Maple syrup urine disease is inherited in an autosomal recessive manner. At conception, each sib of an affected individual has a 25% chance of being affected, a 50% chance of being unaffected and a carrier, and a 25% chance of being unaffected and not a carrier. Once an at-risk sib is known to be unaffected, the risk of his/her being a carrier is 2/3”(Strauss). This represents a Monohybrid Cross.
[pic]This relates to meiosis and fertilization because the passing of the traits to the four daughter haploid cells from the diploid parents. It happens just as a punnet square one child has a chance of being affected, another has a chance of being unaffected and not carrier, and two have a chance of being unaffected but a carrier. IV. The relation between natural selection and the occurrence of MSUD - MSUD is related to natural selection because the Infants that have homozygous dominant are selected against and they will die at a young age....