Patho-Genetic Disorders Flashcards
___ cell mutations do not cause hereditary diseases however are impt in carcinogenesis
Somatic cell mutations
Altered dna codes for a different amino acid
Missense mutation
“Miss different”
Altered dna codes for same amino acid
Silent mutation
Altered dna codes for a stop codon
Nonsense mutation
Occurs if the number of base pairs involved is not a multiple of three
Frameshift mutation
Amplification of a sequence of three nucleotides
Trinucleotide repeat mutations
Important in genetic counseling of people with trinucleotide repeat mutations.
Anticipation
Earlier pattern of disease per generation
Trinucleotide repeat diseases
Huntington’s disease
Myotonic dystrophy
Friedrich’s ataxia
Fragile X syndrome
Name the trinucleotide repeat.
Huntington’s disease
CAG
Name the trinucleotide repeat.
Myotonic dystrophy
CTG
Name the trinucleotide repeat.
Friedrich’s ataxia
GAA
Name the trinucleotide repeat.
Fragile X syndrome
CGG
____ disorders are most often due to defects in structural genes
Autosomal dominant
Penetrance and expressivity of autosomal dominant disorders
Incomplete penetrance
Variable expressivity
Population affected by autosomal dominant disorders
Male and female all generations
Age of presentation of autosomal dominant disorders
Delayed age of onset
Usually presents after puberty
Largest category of mendelian disorders
Autosomal recessive
Autosomal recessive disorders are geberally due to
Enzyme deficiencies
Probability in autosomal recessive that an offspring will get the disease
25%
Term for the affected individual in genetics
Proband
In x linked recessive disorders, the affected male ______ the disorder to his sons
Does not transmit
In x linked recessive disorders, the affected male makes his daughters _______
Carriers
X linked recessive disorders
Bruton's aggamaglobulinemia Wiskott Aldrich syndrome Fabry's disease Fragile X G6PD Ocular albinism Lesch-Nyhan syndrome Duchenne muscular dystrophy Hunter syndrome Hemophilia
Affected heterozygous female in autosomal dominant diseases transmit to ________ sons and ______ daughters
Half
Half
The affected male parent in autosomal dominant disorders transmit ________ sons and ____ daughters
None if female parent is normal
All daughters
X linked dominant disorders
Alport’s syndrome
Vitamin d resistant (hypophosphatemic) rickets
In mitochondrial inheritance, the affected female ______ the disease to all offsprings
Transmits
Examples of diseases with mitochondrial inheritance
MELAS
leber’s hereditary optic neuropathy
Components of MELAS
Mitochondrial myopathy
Encephalomyopathy
Lactic acidosis
Stroke like symptoms
Causes of death in 30-45% of marfan’s
Aortic dissection
Cystic medial necrosis
Autosomal recessive in subtypes of ehlers danlos syndromes
VI kyphoscoliosis type
VIIc dermatosparaxsis
How do u differentiate marfan’s from ehlers danlos in clinical presentation?
Marfans has ectopia lentis, mvp and aortic dissection
____ mutations are transmitted to progeny
Germ cell mutations
Familial hypercholesterolemia
Mutation in
Gene encoding for ldl receptor
Organs affected in tay sachs disease
Cns and retina predominantly
Morphology of tay sachs
Neurons are ballooned with cytoplasmic vacuoles
Whorled configurations (onion skin layers due to gangliosides in lysosomes)
Deficiency in nieman pick disease
Sphingomyelinase
Differentiate the diff types of niemann pick disease
Type A- severe infantile form with extensive neurological involvement and organomegaly
Type B- organimegaly without CNS involvement
Type C: accumulation of cholesterol
Morphology niemann pick disease
Zebra bodies - cytoplasmic bodies resembling concentrated myelin figures
How do you differentiate niemann pick and tay sachs
Niemann pick has hepatosplenomegaly
Most common lysosomal storage disorder
Gaucher’s disease
Mutation in gauchers
Gene encoding glucocerebrosidase
