Lecture 6: Atypical Inheritance Flashcards
__________: a mitochondrial disorder with very severe neurological condition with progressive loss of cognitive and movement abilities typically resulting in death within two to three years
Leigh syndrome: a mitochondrial disorder with very severe neurological condition with progressive loss of cognitive and movement abilities typically resulting in death within two to three years
________\_: a mixture of mutant and wild-type mtDNA. Mitochondrial inheritance disease severity depends on the number of mutant mitochondria acquired.
Heteroplasmy: a mixture of mutant and wild-type mtDNA. Mitochondrial inheritance disease severity depends on the number of mutant mitochondria acquired.
__________: probability that a gene will have a phenotypic expression
__________: all carriers of the genotype will express the phenotype
__________:person carrying mutated gene does not express disease phenotype, hence skipped generations
Penetrance: probability that a gene will have a phenotypic expression
Complete Penetrance: all carriers of the genotype will express the phenotype
_Reduced Penetrance: t_he person carrying mutated gene does not express disease phenotype, hence skipped generations
___________\_: Person carrying a mutated gene can vary in severity of expression of disease.
- Causes are unknown but likely to be genetic or environmental factors that modify the phenotypic expression of the mutant allele
Variable Expressivity: Person carrying a mutated gene can vary in severity of expression of disease.
- Causes are unknown but likely to be genetic or environmental factors that modify the phenotypic expression of the mutant allele
A person ________\_ will not be affected by the disorder caused by the mutation because it is not present in other cells of the body
Genetic testing using blood sample will be ______\_ for the mutation
A person germline mosaicism will not be affected by the disorder caused by the mutation because it is not present in other cells of the body
Genetic testing using blood sample will be negative for the mutation
___________\_: Tendency for some disorders to begin at an earlier age and with increased severity with successive generations eg Huntington’s Disease & Myotonic Dystrophy
- mutation occurs when extra copies are made of a trinucleotide sequence normally present in low copy number
- correlation between _____________\_ and severity of disease
Anticipation: Tendency for some disorders to begin at an earlier age and with increased severity with successive generations eg Huntington’s Disease & Myotonic Dystrophy
- mutation occurs when extra copies are made of a trinucleotide sequence normally present in low copy number
- correlation between number of repeats and severity of disease
____________________:
- Autosomal _________, progressive, ultimately fatal disorder
- Symptoms comprise adult-onset personality changes, generalized motor dysfunction, and cognitive decline
- Severe atrophy of ____\_
- Movement disorder accompanied by behavioral changes including aggression, anxiety, apathy, depression, and cognitive changes affecting memory, awareness, and communication
- 100% penetrant by _____
Huntington’s Disease:
- Autosomal dominant, progressive, ultimately fatal disorder
- Symptoms comprise adult-onset personality changes, generalized motor dysfunction, and cognitive decline
- Severe atrophy of Caudate
- Movement disorder accompanied by behavioral changes including aggression, anxiety, apathy, depression, and cognitive changes affecting memory, awareness, and communication
- 100% penetrant by 70
The mutation responsible for Huntington’s is a CAG repeat (__________ Disorder)
- _____ Repeats: Normal and unaffected
- ______ Repeats: Increased Risk of developing HD
- _____ Repeats: Fully Penetrant
The mutation responsible for Huntington’s is a CAG repeat (Pollyglutamine Disorder)
- 6-35 Repeats: Normal and uneffected
- 36-39 Repeats: Increased Risk of developing HD
- 40-120 Repeats: Fully Penetrant
________________:
- A long, thin face with hollow temples, drooping eyelids and __________ in males
- cataracts, cardiomyopathy, testicular atrophy
- Difficulty relaxing contracted muscles, first noticed in _____, muscle wasting/weakness follow
- Facial muscles are affected leading to an expressionless (masklike) face.
- Death in 50s usually due to pneumonia or heart failure
Myotonic Dystrophy (DM1):
- A long, thin face with hollow temples, drooping eyelids and frontal baldness in males
- cataracts, cardiomyopathy, testicular atrophy
- Difficulty relaxing contracted muscles, first noticed in hand or jaw, muscle wasting/weakness
- Facial muscles are affected leading to an expressionless (masklike) face.
- Death in 50s usually due to pneumonia or heart failure
The mutation responsible for _________is in myotonin kinase gene (DMPK) on Chr 19 a modulator of Ca homeostasis in skeletal muscle
The mutation responsible for Myotonic dystrophy (DM1) in myotonin kinase gene (DMPK) on Chr 19 a modulator of Ca homeostasis in skeletal muscle
DM2 is clinically very similar to DM1 however does not show ______\_
DM2 is clinically very similar to DM1 however does not show congenital form
Most common cause of inherited mental retardation with incidence 1 in 4000 males, 1 in 8000 females.
Fragile X Syndrome
______\_ inheritance pattern of Fragile X
- Risk of being affected seemed to _______ going down through generations
- Found apparently normal male at top of pedigree who had several carrier daughters and normal transmitting males
- Sometimes found women with some degree of mental retardation
Atypical inheritance pattern of Fragile X
- Risk of being affected seemed to increase going down through generations
- Found apparently normal male at top of pedigree who had several carrier daughters and normal transmitting males
- Sometimes found women with some degree of mental retardation
Behavioural features of ________:
- Social anxiety and withdrawal
- Gaze aversion
- Social deficits with peers
- Deficit in attention
- Hyperactivity
- Impulsiveness
- Hyperarousal and unusual response to sensory stimuli
- Handflapping and handbiting
Behavioural features of Fragile X Syndrome:
- Social anxiety and withdrawal
- Gaze aversion
- Social deficits with peers
- Deficit in attention
- Hyperactivity
- Impulsiveness
- Hyperarousal and unusual response to sensory stimuli
- Handflapping and handbiting
_______ is most common single gene cause of autism spectrum disorders
Fragile X Syndrome is most common single gene cause of autism spectrum disorders
