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36 Cards in this Set
- Front
- Back
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a cell that contains one less than the normal number of chromosomes is called a ...
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monosomy
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extra chromosomes... extra member to a normal pair
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trisomy
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segment of one chormosome breaks off and attaches to another chromosome
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translocation
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trisomy 21
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down syndrome
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a trisomy of every pair
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triploidy
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are caused by a mutation or change in a single gene on a chromosome or the matched gene pair on both chromosomes
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single gene defects
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inherited diseases caused by absence or defficiency in metabolism
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inborn errors of metabolism (IEM)
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s/s of congenital hypothyroidism
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prolonged jaundice
constipation umbilical hernia quiet and good baby |
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inability to metabolize the enzyme phenylalanine
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PKU
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what is the deficient enzyme in PKU
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phenylalanine hydroxylase
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absent amino acid from missed metabolism of phenylalanine
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tyrosine
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products of tyrosine
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epinephrine
melanin thyroxine |
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suspect PKU when child has ..
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blonde hair
blue eyes fair skin |
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complications of PKU
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neurological disorders
schizoid behavior defective myelinization |
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test for PKU
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Guthrie blood test
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normal Phenylalanine value
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1.6 mg/dL (2-6 mg/dL)
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defects in chromosomal NUMBER primarily in germ cells during meiosis
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NONDISJUNCTION (meiosis)
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all abnormal cells in the final stage = nondisjunction
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primary
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some normal cells in the final stage = nondisjunction
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secondary
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failure of chromosome pairs to separate properly during cell division that occurs AFTER fertilization during early cell division
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nondisjunction (mitosis)
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when some cells have 46 chromosomes and other cells have extra copy
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Mosaic cells
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what to remember with nondisjunction?
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the earllier the non-disjuncion, the less chance for normal cells
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a chromosome abnormality caused by rearrangement of parts between nonhomologous chromosomes.
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translocation
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risk factor: maternal age stats for Down syndrome
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1:400 = 35 years
1:110 = 40 years |
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Carriers of both normal and abnormal chromosomes
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mosaics
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most common physical problems with Down syndrome
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congenital septal defects
Respiratory tract infections hi-risk of leukemia congenital hypothyroidism |
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a gamete (i.e., a sperm or egg cell) is produced with an extra copy of chromosome 21; the gamete thus has 24 chromosomes. When combined with a normal gamete from the other parent, the embryo now has 47 chromosomes, with three copies of chromosome 21.
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nondisjunction Down syndrome (nonfamilial)
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cause of 1–2% of the observed Down syndromes.[25]
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mosaicism
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aka familial Down syndrome
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translocation Down syndrome
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is a genetic disorder in which a person has three copies of genetic material from chromosome 13, instead of the usual two copies. Rarely, the extra material may be attached to another chromosome (translocation).
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trisomy 13
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If a pair of sex chromosomes fails to separate during the formation of an egg (or sperm), this is referred to as
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nondisjunction
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is caused by a missing or incomplete X chromosome.
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Turner's syndrome (45 chromosomes)
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is typically caused by what is called nondisjunction. If a pair of sex chromosomes fails to separate during the formation of an egg (or sperm)
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sex chromosome disorder
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is a form of chromosomal variation characterized by the presence of an extra X chromosome in each cell of a human female.
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superfemale (triple x syndrome)
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Each affected person usually has one affected parent. There is a 50% chance that a child will inherit the mutated gene. Only one mutated copy of the gene will be necessary for a person to be affected
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autosomal dominant
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An affected person usually has unaffected parents who each carry a single copy of the mutated gene (and are referred to as carriers). Two copies of the gene must be mutated for a person to be affected
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autosomal recessive
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