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Flashcards in Heredity And Disease Deck (50):
1

Deoxyribonucleic acid

DNA

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44 of the chromosomes are called what?

Autosomes

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What are the remaining two chromosomes called?

X and Y chromosomes

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The complete chromosomal composition of the nucleus

Karyotype

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What are alleles?

Alternative forms of a gene

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Hereditary diseases or disorders are generally the result of what?

Metabolic breakdown caused by a lack of direction from a missing or compromised gene or chromosomal segment.

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What is the most common genetic disorder states?

Hemochromatosis

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This allele is usually transmitted from a parent who is heterozygous for the trait.

Autosomal dominant

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An example of an autosomal dominant disorder which involves extra fingers or toes developing.

Polydactyly

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Another disorder resulting from one defective dominant allele. Cartilage formation in the fetus is abnormal. The long bones of the arms and legs are short, the trunk of the body normal in size, the head is large and forehead prominent.

Achondroplasia

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Results from the dysfunction of the gene that normally codes for the connective tissue to protein fibrillin which is necessary for maintenance of connective tissue's in various organs, tendons, heart valves, and blood vessels. Causes skeletal changes, floppy heart valves, and ocular changes.

Marfan syndrome

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Caused by mutation in the gene encoding the receptor for low density lipoprotein (too many LDLs and body can't remove cholesterol from blood). This inefficiency results in accelerated atherosclerosis and incidence of coronary heart disease.

Family hypercholesterolemia (FH)

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Manifest themselves only when a person is homozygous for the defective allele

Autosomal recessive diseases

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An inborn error of metabolism caused by autosomal recessive allele. Person's lack a specific enzyme that converts phenylalanine to tyrosine. Results in higher levels of phenylalanine to build up in the blood and is toxic to the brain.

Phenylketonuria (PKU)

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Where are the signs and symptoms of phenylketonuria?

Patient has disorders of the nervous system, such as lack of balance, tremors, and hyperactivity, and may suffer convulsions. Person must avoid consuming phenylalanine.

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Another example of an inborn error of metabolism from autosomal recessive inheritance. Person lacks enzyme to convert galactose to glucose. Galactose accumulates in blood and interferes with development of brain, liver, and eyes.

Galactosemia

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What are the signs and symptoms of galactosemia?

If untreated, mental retardation develops. Liver becomes enlarged and cirrhotic, and ascites fluid accumulates in abdominal cavity. Intestinal distress results in vomiting and diarrhea.

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How do you treat galactosemia?

Consist of eliminating lactose from the diets or taking supplements to assist digestion and reduce symptoms.

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A severe anemia generally confined to the black population. And autosomal recessive disorder in which hemoglobin is abnormal, resulting in deformed red blood cells.

Sickle cell anemia

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What are the symptoms and signs of sickle cell anemia?

Improperly formed cells become lodged in capillaries and block circulation, causing infarcts, pain, and necrosis. Depletion of red blood cells results in severe anemia.

21

And autosomal recessive condition that primarily affects families of eastern Jewish origin. Because of an absence of an enzyme, a lipid called GM2 ganglioside accumulates in cells, especially nerve cells of the brain.

Tay-Sachs

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What are the signs and symptoms of Tay-Sachs?

Symptoms appear by six months when no new skills are learned, convulsions occur, and blindness develops. Children usually died between two and four years of age.

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An autosomal recessive disorder that is easily recognized. The skin and hair color are very white and do not darken with age.

Albinism

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What are the symptoms and signs of albinism?

People have increased risk for skin cancer and exhibit visual problems such as nearsightedness and abnormally high sensitivity to light.

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Diseases that are generally result from defective genes on the X chromosome, because the Y chromosome is small and carries very few genes.

Sex-linked inheritance

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Why do males have a better chance of getting a sex linked disease then females?

Males only have one X-chromosome, so defective recessive gene is expressed. Females can be heterozygous and will only be a carrier.

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The inability to distinguish between certain colors, is a disorder of sex linked inheritance. Person is unable to distinguish reds and greens. Corrective lenses may offer treatment.

Color blindness

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People do not bleed more profusely or bleed faster than normal; they bleed for a longer period of time. Factor VIII is usually inactive in cases of this disease.

Hemophilia

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Can we treat hemophilia?

There have been significant advances in treating hemophilia in the last decade. New genetically engineered clotting proteins is now used for treatment in some types. Research is underway to develop gene therapy.

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A genetic condition associated with mental retardation is identified by thin, threadlike strands on the long arm of the X-chromosome.

Fragile X syndrome

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What are the signs and symptoms of fragile X syndrome?

Majority of patients are mildly to moderately retarded. Men and boys are socially engaging, but have unusual style of interacting. Avoid eye contact, and slapping or hand biting is common. Unusual speech with narrow face, and protruding ears.

32

Some diseases appear in families, but the means of inheritance is not understood. Examples are families with high incidence of epilepsy, diabetes, cardiovascular problems, allergies, and familial polyposis.

Familial diseases

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Cause of these diseases does not seem to be a single gene but the effect of several genes working together

Multifactorial

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An example of a disorder caused by the presence of an extra autosomal chromosomes. Chromosome 21 is inherited in triplicate, a condition called trisomy 21.

Down syndrome

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What are the symptoms and signs of down syndrome?

I appear slanted because of extra fold of skin at the upper, medial corner of that I; Tonyas course and often protrudes; and nose is short and flat. Is usually short in stature. Life expectancy is short because of complications that accompanied the condition.

36

Caused by deletion of part of the short arm of chromosome 5. Infants have abnormally small head with a deficiency of cerebral brain tissue.

Cri du chat syndrome (cat cry syndrome)

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What are the symptoms and signs of cri du chat syndrome?

Those born alive has a week, catlike cry. Eyes are spaced far apart and children exhibit mental retardation. Infant dies usually in first five or six years.

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One of the sex chromosomes is missing, resulting in a karyotype of 45, XO, indicating the presence of 45 chromosomes with only one X chromosome.

Turner syndrome

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What are the symptoms and signs of turner syndrome?

Person appears female, but ovaries do not develop. Thus, no ovulation or menstruation, and person is sterile. Person is short of stature and has stocky build. Heart problems frequently accompanied turner syndrome. Facial deformities are often present.

40

An extra sex chromosome is present, resulting in a karyotype of 47, XXY, indicating the presence of 47 chromosomes, including two X and one Y chromosomes.

Klinefelter syndrome

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What are the symptoms and signs of Klinefelter syndrome?

Person appears to be male but has small testes and failed to mature and produce no sperm. At puberty, the breasts enlarge and female distribution of hair develops. There is little facial hair and general appearance is that of immature young adult. Person is tall and slender.

42

A person with both testes and ovaries. Is referred to as sex reversal, in which the chromosome will sex is different from the anatomic sex. Person develops anatomically female but chromosomally male.

Hermaphrodite

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How can people get an early diagnosis of genetic diseases?

Amniocentesis after the 14th week of pregnancy. Chromosomes are examined and anabiotic fluid is examined for biochemical abnormalities.

44

Are those diseases appearing at birth or shortly after, but they are not caused by genetic or chromosomal abnormality's. Usually result from some failure in development during the embryonic stage, or first two months of pregnancy.

Congenital defects

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A gap between the left and right halves of the lip or upper palate.

Cleft lip and cleft palate

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Absence of a normal opening in an organ is called

Atresia

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A complete obstruction of the intestine, resulting in vomiting, dehydration, scanty stool production, and distention of the abdomen.

Intestinal atresia

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The pyloric sphincter are hyper trophies, closing the opening between the stomach and the beginning of the small intestine nine. Shows projectile vomiting, dehydration, constipation, and weight loss.

Pyloric stenosis

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Bile ducks are blocked, causing severe jaundice to develop. Liver and spleen become greatly enlarged.

Biliary atresia

50

Review questions on page 106

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