Genetic Modes Of Inheritance Flashcards by Morgan C

Who do x linked disorder occur most severe in

Males

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What type of disorder is duchenne muscular dystrophy? Why type of abnormality is it?

X linked, out of frame deletion so dystrophin is not functional

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What type of disorder is Becker muscular dystrophy? Why type of abnormality is it?

X linked, in frame deletion

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What is an out of a frame mutation

Deleted message does not fit together

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What is an in frame mutation

Deleted message fits together

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What type of disorder is hemophilia?

X linked

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What happens in hemophilia

Clotting doesn’t happen as it should. Missing factor eight? A missing factor nine? B

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What is Becker muscular dystrophy

Allelic form, less severe, occurs later in life

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Clinical manifestations of duchenne muscular dystrophy

Passed away from heart and lung complications, need wheelchair by age 13, males show weakness early on, difficulty getting off the floor, calf hypertrophy

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What type of disorder is menkes syndrome/ kinky hair syndrome

X linked

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Clinical features of menkes syndrome/kinky hair syndrome

Abnormal/sparse kinky hair, hypotonic, seizures, failure to thrive, motor loss, usually die by age 3 but those who survive are disabled

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Mike menkes?

Some function of the protein still there so clinical manifestations are not as severe

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What happens to males in menkes syndrome/kinky hair syndrome

They do not reproduce

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What is haldanes syndrome in kinky hair syndrome?

Affected males do not reproduce but disease incidence stays the same every year. This means that 1/3 of cases each year are new mutations

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In what disorder is there a copper transport ATPase error leading to low copper and ceruloplasmin

Menkes disorder

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Who is most affected in X-linked recessive disorders where the mother is the carrier

Males because they only have one copy of the X. Daughters can only be carriers

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How are daughters affected in excellent recessive disorder’s where the father is affected? Sons?

all daughters are carriers and all sons are unaffected

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Is there male to male transmission in X-linked recessive disorders?

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As is there make to make transmission in x linked dominant disorders

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Where is there vertical transmission?

X linked dominant disorders

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What happens if males are affected in x linked dominant disorders

Males are not affected bc you get a miscarriage

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What type of disorder is hypophosphatemic rickets

X linked dominant male lethal

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Clinical manifestations of hypophosphatemic rickets

Bowing of lower extremities

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Clinical manifestations of aicardi syndrome

agenesis of corpus callosum, distinctive chorioretinal lacunae (lakes in retina)

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Type of disorder of aicardi syndrome

X linked dominant male lethal

Clinical manifestations of incontinentia pigmenti

Affects hair skin nails teeth (ectoderm) , seizures, cognitive delay, retinal detachment

Type of disorder of incontinentia pigmenti

X linked dominant male lethal

What disorder has 4 stages

Incontinentia pigmenti

4 stages of incontinentia pigmenti

Blistering Wart like rashes Swirling, macular, hyperpigmentation Lines of lashko, linear hypopigmentation, mimic Christmas tree

Type of disorder of rett syndrome

X linked dominant male lethal

Clinical manifestations of Rett syndrome

Microencephalopathy, regression, seizures, hand wringing

What happens with the transmission in y linked disorders

Male fathers pass to all sons

What are sex limited disorders

Disorders where it will only affect one sex such as breast cancer

What are sex influence disorders

Disorders where both sexes can have the disorder but will express it in different ways such as pattern baldness

Who passes mitochondrial inheritance on

Females only

is there a high mutation rate in mitochondrial inheritance

Yes because there is no repair mechanism

What is heteroplasmy

Some mitochondria I have mutations in some don’t. May not reach threshold so some people are asymptomatic

What is Homoplasmy

Mutations in all mitochondria so high likelihood of symptoms

What does MELAS stand for

Mitochondrial encephalopathy, lactic acidosis, stroke like episode

Symptoms of MELAS?

Seizures, headaches, vomiting, 2 to 10 years old

What type of disorder is MELAS

Mitochondrial inheritance

What type of disorder is MERRF

Mitochondrial inheritance that is heteroplasmy

What does MERRF stand for

Myoclonic epilepsy with ragged red fibers

What type of mutation is MERRF?

Point mutation

Clinical manifestations of MERRF

Ataxia, dementia

What type of disorder is LHON

Mitochondrial inheritance

What does LHON stand for

Leber hereditary optic neuropathy

Clinical manifestations of LHON

Sudden blurred vision in adulthood beginning with one eye

What type of mutation is LHON

3 Point mutations all with different penetrancd

Are more males or females affected in LHON

Males

What is penetrance

Either have the symptoms or don’t; 100% means you have all the symptoms

What is variable expressitivity

Severity of symptoms

What is vertical transmission

Inheritance is in every generation

If there is vertical transmission what type of disorder is it? What if there is no vertical transmission?

Yes- dominant | No- recessive

If there is only male to male transmission what type of disorder is it? What if it’s not?

Yes- y linked | No- not y linked

What type of disorder is it if only one sex is affected? What if not?

Yes- x linked | No- autosomal

What if affected mothers have unaffected kids?

Yes- not mitochondria | No- mitochondrial

Epigenetic factors?

methylation; some genes on at certain times and some off

Are there mutations at the nucleotide level in epigenetic factors

What type of disorder is Prader willi syndrome PWS

Genomic imprinting; deletion of paternal 15 q

What disorder has early feeding problems then hyperphagia

PWS

Clinical manifestations of PWS

Short, intellectual disability, behavioral problems, hypogonadism

MC genetic causes obesity?

PWS

What disorder is also called happy puppet

Angelman syndrome (AS)

Clinical manifestations of AS

Small head, arm flapping, ataxia, inappropriate laughter, no speech, intellectual disability

What type of disorder is Angelman syndrome

Genomic imprinting 15 q deletion of maternal

What is the chromosome difference in Beckwith Weidman syndrome (BWS)

P 11 methylation defect

Clinical manifestations of beckwith Weidman syndrome (BWS)

Overgrowth, enlarged tongue, body, and organs , body asymmetry, abdominal wall defects, hemangiomas, earlobe crease

What are the clinical manifestations of Russell silver syndrome (RSS)

Undergrowth, intrauterine growth, retardation, triangular faces, finger clinidactyly, abnormal sweating, body asymmetry

Dynamic mutations?

Repeat become unstable after certain number of repeats

Anticipations?

Larger repeats so symptoms are early onset and more severe

Premutations?

Repeat size length are more than normal but they have less than the disease state

What type of disorder is myotonic dystrophy

Autosomal dominant, triplet repeat disorder

What type of disorder is congenital myotonic dystrophy

Autosomal dominant, triplet repeat disorder with more expansions than myotonic alone

What type of disorder is Huntington disease

Autosomal dominant, Triple repeat of CAG

Clinical manifestations of myotonic dystrophy

Myotonia, Face muscle atrophy and weakness, cataracts, heart condition, low IQ

What is myotonia

Can’t release grip

Clinical manifestations of congenital myotonic dystrophy

Severe hypotonia, failure to thrive, intellectual disability

Clinical manifestations of Huntington disease

Decreased motor control, drunk movements, changing mood, memory trouble

What type of disorder is fragile X syndrome

X linked, trinucleotide repeat of FMR1 gene

What do the symptoms vary based on in fragile X syndrome

Number of repeats like pre-mutation or full mutation

Who is fragile X more common in males or females?

Females

What is the most common inherited form of intellectual disability

Fragile X syndrome

Clinical manifestations of fragile X syndrome

Long face, protruding ears, autistic behavior, intellectual disability

What causes Russell silver syndrome (RSS)

Most ppl have 11P15.5 methylation defects, others have a maternal uniparental disomy of chromosome 7, the rest is unknown