What is the chromosome abnormality that causes Down syndrome quizlet?
Down syndrome is caused by a random error in cell division that results in the presence of an extra copy of chromosome 21.
Which of the following are characteristics of Down syndrome quizlet?
- eyes that slant upward, have oblique fissures, have epicanthic skin folds on the inner corner, and have white spots on the iris.
- low muscle tone.
- small stature and a short neck.
- a flat nasal bridge.
- single, deep creases across the center of the palms.
- a protruding tongue.
What causes Down syndrome quizlet?
The syndrome is caused by an extra copy of Chromosome 21, and in today’s Nature paper, researchers at the University of Massachusetts Medical School describe a way to “silence” that extra chromosome, meaning it’s still there but its genes don’t get “turned on,” they don’t function and cause problems.
What causes Down syndrome in pregnancy?
Down syndrome is usually caused by an error in cell division called “nondisjunction.” Nondisjunction results in an embryo with three copies of chromosome 21 instead of the usual two. Prior to or at conception, a pair of 21st chromosomes in either the sperm or the egg fails to separate.
Is Down syndrome caused by nondisjunction?
Nondisjunction of chromosome 21 is the leading cause of Down syndrome. Two risk factors for maternal nondisjunction of chromosome 21 are increased maternal age and altered recombination.
What is most likely cause of these chromosomal abnormalities?
The most common cause of chromosomal abnormalities is the age of the mother. As the mother ages, the ovum is more likely to suffer abnormalities due to longer term exposure to environmental factors. Consequently, some gametes do not divide evenly when they are forming.
Which chromosomal mutation will cause Williams syndrome?
Williams syndrome is caused by the spontaneous deletion of 26-28 genes on chromosome #7 at the time of conception. The deletion can occur in either the egg or the sperm.
Which abnormality would a patient with Down syndrome present dental quizlet?
TOOTH ANOMALIES are common in Down syndrome. Congenitally missing teeth occur more often in people with Down syndrome than in the general population. Third molars, laterals, and mandibular second bicuspids are the most common missing teeth.
What causes the most common chromosomal abnormality called trisomy 21?
Abstract. Trisomy 21 (Down syndrome) is the most common autosomal trisomy in newborns, and is strongly associated with increasing maternal age. Trisomy 21 results most commonly from maternal meiotic nondisjunction. Unbalanced translocation accounts for up to 4% of cases.
What genetic disorder is caused by having three chromosomes 21 quizlet?
Also known as Down syndrome, trisomy 21 is a genetic condition caused by an extra chromosome. Most babies inherit 23 chromosomes from each parent, for a total of 46 chromosomes. Babies with Down syndrome however, end up with three chromosomes at position 21, instead of the usual pair.
Which of the following is a physical manifestation of Down syndrome quizlet?
Common physical signs of Down syndrome include1,2: Decreased or poor muscle tone. Short neck, with excess skin at the back of the neck. Flattened facial profile and nose.