Lecture 18 Flashcards
what is genetic counseling?
the process of advising individuals and families affected by or at risk for genetic disorders to help them understand and adapt to the medical psychological, and familial implications of genetic contributions to disease
what three things does the process of genetic counseling integrate?
- interpretation of familial medical history to assess the chance of disease occurrence and reoccurrence
- education about inheritance, testing, management of genetic information, prevention, and resources
- counseling to promote informed couches and adaptation to the risks of the condition
describe the inheritance pattern for an autosomal dominant disorder:
vertical transmission of disease - at least on affected individual in each generation
what is required in order to present the disease in an autosomal dominant disorder?
only one mutated copy of the gene
even though an autosomal dominant disorder is passed down through every generation, what is possible in regards to the presentation of the disorder?
the reduction of penetrance is possible - not all individuals who inherit the mutation develop the disease
what is Charcot -Marie -Tooth Syndrome?
a type of inherited neurological disorder that affects the peripheral nerves
what is achondroplasia?
a disorder of bone growth that prevents the changing of cartilage (particularly in long bones of the arms or legs) to bone
what type of inheritance pattern is an autosomal recessive disorder characterized by?
horizontal transmission - affected individual receives two mutated copies from their parents that are healthy carriers
if there is an x-linked dominant disorder, what is the probability that the disease will be passed down to the offspring?
affected father: all suns are unaffected but all daughters are affected
affected mother: 50% of all offspring affected
if there is an x-linked recessive disorder, what is the probability that the disease will be passed down to the offspring?
affected father: all sons are unaffected and all daughters are carriers
affected mother: 50% of sons are affected, and 50% of daughters are carriers
if there is a y-linked disorder, what is the inheritance pattern?
- only males affected
- affected males usually have affected fathers
- affected males will have affected sons
what is mitochondrial inheritance?
a sever disorder due to mutations in genes encoded by mitochondrial DNA
who is mitochondrial DNA transmitted by?
mothers
in some cases, genetic disorders are characterized by specific craniofacial abnormalities - what is measured after birth to screen for these?
- head circumference
- external and internal intercanthal distance (distance between orbits)
- facial characteristics
- palate evaluation
what is it called when the size of the head is more than two standard deviations under the normal measurement?
microencephaly of the occipital front circumference (OFC)
