Genetic Basis for disease Flashcards
What is genetics
study of hereditary, focused on single gene (develop treatment plans)
What is a gene?
unit of heredity
- sequence of nucleotides
- determines structure or has regulatory function in a cell
Chromosomes?
Linear arrangement of genes within the cell nucleus
- normal = 23 pairs
22 paurs of autosomes and 1 sex chromosome XX or XY
Homozygous vs. heterozygous
homo = processing pair of identical genes
hetero= different genes on a pair of chromosomes
What is genomics?
study of all genes, genetic inter-relationship and their influence on growth and development
What is congenital disorder?
abnormalities of a body structure, function, or metabolism & present at birth
1. Chromosomal disorder
2. Single gene disorder
3. Multifactorial disorder
If someone has a numerical disorders what does that mean?
(number of chromosomes) loss of chromosome = more serious (death)
euploidy
normal number of chromosomes
Aneuploidy
abnormal cells do not contain chromosomes in multiples of 23
What is the cause of Aneuploidy?
nondisjunction (abnormal in daughter cells)
- Failure of chromatid pairs to separate
- Results in unequal number of chromosomes in daughter cell
What are the 2 types of aneuploidy?
- autosomal (abnormal of chromosomes in a somatic cell 13, 18, 21
- Trisomy = when a cell contains one extra copy of any the chromosomes - Monosomy (when a cell only contains only 1 copy of any of the chromosomes instead of 2 (loss of chromosomes)) LEATHAL
What is an example of autosomal genetic disorder?
down syndrome
- facial abnormalities
- intellectual disability/low IQ, poor muscle tone, short stature, systemic disorders, mortality
- Increased risk with increased maternal age
What are the 2 examples of sex chromosome disorder?
klinefelter syndrome and turner syndrome
what is Klinefelter Syndrome? clinical manifestations?
at least 2 XX and one Y
- male appearance but female features, moderate IQ
What is turner syndrome? clinical manidestations?
x chromosome monosomy = only females with only 1 X chromosomes
- webbed neck, shield like chest, faulty ovary development, short stature, narrow aorta, some IQ impairment
What is polyploidy?
- more that 2 complete sets of chromosomes
child will die
tetraploidy - 92 chromosomes
triploidy - 69 chromosomes
tetraploidy vs. triploidy
tetraploidy - 92 chromosomes
triploidy - 69 chromosomes
What are some structural disorders?
Deletions
Duplication
Inversion
Translocation
Fragile sites
Deletions example of disorder?
loss of portion of a chromosome
- Cri Du Chat Syndrome = low birth weight, microcephaly, heat heart defects, intellectual disability
Duplication
presence of a repeated gene or gene sequence
Inversion
reversal of gene order - entire or just portion
Translocation
transfer of one part of a chromosome to another
Fragile sites example ?
chromosome parts that develop distinctive breaks and gaps
- fragile X syndrome: only effects X chromosome (only in males)
2nd most common genetic disorder
What are the 2 branches off of chromosomal disorder?
- numerical disorder
- structural disorder
What are the 3 branches off of Single gene disorders?
- autosomal dominant
- autosomal recessive
- sex chromosomes
Autosomal dominant? example?
abnormal gene is dominant and normal gene is recessive
Marfan’s Syndrome: connective tissue disorder involving skeletal, ocular, and cardiovascular systems
- Thin tall arm span is longer than there height – life threatening later in life because of their weakened aorta
Autosomal Recessive? example?
abnormal gene is recessive and normal gene is dominate
- Phenylketonuria (PKU) part of newborn screening
- Cystic Fibrosis
What is PKU?
Phenylketonuria
Inability of body to convert phenylalanine to tyrosine = elevated levels of phenylalanine (toxic to cns) & deficient tyrosine
- Accumulation in the blood and excess causes alterations in nervous system development Metabolic system disturbances
- Tests now available for detection = tests for autism, seizure disorders
What is PKU?
Phenylketonuria
Inability of body to convert phenylalanine to tyrosine = elevated levels of phenylalanine (toxic to cns) & deficient tyrosine
- Accumulation in the blood and excess causes alterations in nervous system development Metabolic system disturbances
- Tests now available for detection = tests for autism, seizure disorders
Sex chromosome disorders in single gene disorders? example?
most x link recessive - more in males b/c it take 2 copies for female
- Duchenne Muscular Dystrophy
- Fragile X Syndrome
What is the difference between sex limited and sex influenced?
Sex limited - trait only occurs in 1 gender = testicular defects … uterine defects
Sex influenced = trait only occurs more often in one gender than the other = breast cancer, balding
What is multifactorial genetic disorder?
Interaction between genetic susceptibility and environment (living environment)
- more frequently in females
What are some multifactorial genetic examples
Examples cleft lip and palate, neural tube defects, club feet, some congenital heart defects, diabetes mellitus, hypertension, some types of cancer
What is a teratogen? examples?
Enviormental problems that could harm there baby
- medication, smoking, drugs and alcohol, mothers health, radiation, malnutrition, micoorganisms
What is TORCH?
panel of tests based on living conditions for baby
- Toxoplasmosis
- other
- Rubella
- cytomegalovirus
- herpes
What is Toxoplasmosis
from cat pee, undercooked meat, unpasteurized milk
- Eye infections and intellectual disability and miscarriage
rubella?
baby will be still born
what is cytomegalovirus?
transmitted though body secretions (milk)
- Death, intellectual disability
Herpes
Herpes – can be spread during birth STI
What is the outcome of a terogen?
congenital defects
what is a recurrence risk?
probability of an individual will develop a genetic disease
What would be the transmission rate in autosomal dominant for an affected parent and normal parent?
50%risk
What would be the transmission rate in autosomal dominant for an affected parent and an affected parent
75% risk
What would be the transmission rate in autosomal recessive for an heterozygous parent and heterozygous parent =
25% risk
What would be the transmission rate in autosomal recessive for an heterozygous parent and affected parent =
50% risk
Can there be a genetic disorder in a child whos parents do not carry the gene?
yes even tho there is no history of disease in family there could a a probable new mutation in a parents genes
