8/15 - Genetic Disorders Flashcards
human genetic disorders are broadly classified into what categories
- mutations in SINGLE genes w/ large effect disorders
- chromosomal disorders
- complex multigenic disorders
what mutations cause the disease or predispose to the disease and are typically not present in normal peopl
mutations in single genes w/ large effects
what mutations and their associated disorders are highly penetrant (presence of mutation is associated w/ disease in large proportion of individuals)
mutations in single genes w/ large effects
what mutation usually follow Mendelian pattern of inheritance
mutations in single genes w/ large effects
what specific DNA mutations cause large effect in gene mutation
deleted, inserted, and substituted
chromosomal disorders arise from structural or numerical alterations in what??
autosomes and sex chromosomes
what disorder is uncommon but associated with high penetrance
chromosomal disorders
how do chromosomal disorders specifically cause mutation
- single chromosome mutation - deletion, duplication, inversion
- insertion
- translocation
what sis the most common genetic disorder of the three
complex multigenic disorders
what causes complex multigenic disorders
interactions btwn multiple variant forms of genes and environmental factors
variations in genes are common within population and are also called ___
polymorphism
in complex multigenic disorders, does each variant gene confer a small increase in disease risk, and no single susceptibility to genes is necessary or sufficient to produce the disease
YES
what is a permanent change in the DNA
mutation
mutations affect ___ cells and are transmited to the progeny and can give rise to ___ diseases
germ; inherited
mutations that affect ___ cells do not cause hereditary diseases but are important in the genesis of cancers and congenital malformations
SOMATIC cells
A ___ is a change in which a single
base is substituted with a different base
point mutation
sickle cell anemia is an example of what mutation
point mutation (valine is substituted for glutamic acid)
types of gene mutations
- point mutations within coding sequences
- mutations within noncoding sequences
- deletions and insertions
- trinucleotide repeat mutations
point mutations or deletions involving regulatory sequences may interfere with what
binding of transcript factors
thalassemia is an example of what mutation
mutations within noncoding sequences (interfer w/ binding of transcript factors)
what is a noncoding, intervening sequence of DNA within a gene
intron
small deletions and insertions involving the coding sequence effect ___
the encoded proteins
cystic fibrosis is an example of what mutation
deletion
fragile X syndrome is an example of what mutation
insertion and trinucleotide repeat mutations
what is characterized by amplification of sequence of three nucleotides
trinucleotide repeat mutations
almost all affected sequences in trinucleotide repeat mutations share what nucleotide
guanine (G) and cytosine (C)
what disease and what is this example of:
there are 250 to 4000 tandem repeats of the sequence CGG within a gene called familial mental retardation 1 (FMR1); this prevents normal expression of FMR1 gene, giving rise to mental retardation
fragile X syndrome - example of trinucleotide repeat mutations
Virtually all Mendelian disorders are the result
of mutations in ___ that have large
effects
single genes
T/F: most mutations in autosomal genes produce partial expression in HOMOZYGOTE and full expression in HETEROZYGOTE
FALSE!
most mutations in autosomal genes produce partial expression in HETEROZYGOTE and full expression in HOMOZYGOTE
mutations involving single genes typically follow what three patterns of inheritance
- autosomal dominant
- autosomal recessive
- X-linked
