A man in his early 30s suddenly developed weakness in hishands and neck, followed weeks later by burning musclepain—all symptoms of late-onset muscular dystrophy. Hisinternist ordered genetic tests to determine whether he had oneof the most common adult-onset muscular dystrophies—myotonicdystrophy type 1 (DM1) or myotonic dystrophy type 2 (DM2). Thetests detect mutations in the DMPK and CNBP genes, the onlygenes known to be associated with DM1 and DM2. While awaitingthe results of the gene tests, the internist explained that thedisease-causing mutations in these genes do not result in changesto the coding sequence. Rather, myotonic dystrophies resultfrom increased, or expanded, numbers of tri- and tetranucleotiderepeats in the 3 untranslated region of the DMPK or CNBP genes.The doctor went on to explain that the presence of RNAs withexpanded numbers of repeats leads to aberrant alternative splicingof other mRNAs, causing widespread disruption of cellular pathways.This discussion raises a number of interesting questions. What role might the expanded tri- and tetranucleotide repeatsplay in the altered splicing?
DNA and RNA
Deoxyribonucleic acid (DNA) is usually called the blueprint of life. Deoxyribose is a monosaccharide that has a key function in the synthesis of deoxyribonucleic acid. One less oxygen-containing hydroxyl group occurs in deoxyribose sugar. Nucleic acid, deoxyribonucleic acid, is one of the natural components. Deoxyribonucleic acid is a double-stranded molecule. Watson and Crick postulated the double-stranded model of the helix. A deoxyribonucleic acid is a molecular group that carries and transmits genetic information from parents to offspring. All eukaryotic and prokaryotic cells are involved.
DNA as the Genetic Material
DNA, or deoxyribonucleic acid, is a long polymeric nucleic acid molecule discovered in the late 1930s. It is a polymer; a long chain-like molecule made up of several monomers connected in a sequence. It possesses certain characteristics that qualify it as a genetic component. Certain organisms have different types of nucleic acids as their genetic material - DNA or RNA.
Genetics
The significant branch in science which involves the study of genes, gene variations, and the organism's heredity is known as genetics. It is also used to study the involvement of a gene or set of genes in the health of an individual and how it prevents several diseases in a human being. Thus, genetics also creates an understanding of various medical conditions.
DNA Replication
The mechanism by which deoxyribonucleic acid (DNA) is capable of producing an exact copy of its own is defined as DNA replication. The DNA molecules utilize a semiconservative method for replication.
A man in his early 30s suddenly developed weakness in his
hands and neck, followed weeks later by burning muscle
pain—all symptoms of late-onset muscular dystrophy. His
internist ordered genetic tests to determine whether he had one
of the most common adult-onset muscular dystrophies—myotonic
dystrophy type 1 (DM1) or myotonic dystrophy type 2 (DM2). The
tests detect mutations in the DMPK and CNBP genes, the only
genes known to be associated with DM1 and DM2. While awaiting
the results of the gene tests, the internist explained that the
disease-causing mutations in these genes do not result in changes
to the coding sequence. Rather, myotonic dystrophies result
from increased, or expanded, numbers of tri- and tetranucleotide
repeats in the 3 untranslated region of the DMPK or CNBP genes.
The doctor went on to explain that the presence of RNAs with
expanded numbers of repeats leads to aberrant alternative splicing
of other mRNAs, causing widespread disruption of cellular pathways.
This discussion raises a number of interesting questions.
What role might the expanded tri- and tetranucleotide repeats
play in the altered splicing?
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