genetic testing and counseling Flashcards
assortative mating
mating of people that have the same phenotype results in more of the phenotype to be present
-i.e. within the Deaf community, when two deaf individuals mate this results in more deaf people being born
linguistic homogamy
mating between individuals that have the same language as native signers
-prime example if within the Deaf community and using ASL
founder effect
has common ancestors
-consanguinity creates a small gene pool, there will be carriers and then an individual will need 2 bad identical genes
population bottleneck
reduction in population size, which enhances the effects of gene drift
gene drift
random fluctuations in the numbers of gene variants in a population
balanced polymorphism
being heterozygous for a certain disease leads to protection from other diseases
-being homozygous for the disease (with showing phenotype or not) does not protect you
how to identify affected individuals
-perinatal history (what happens in the first month of life)
-speech and language milestones
-history of poor motor development
-family history
-physical examination
-audiologic examination
-laboratory tests
-endocrine function
-electrocardiagram
-radiology
know factors within the perinatal history
low birth weight, time spent in NICU, certain infection, use of ototoxic medication or hypoxia
know factors within family history
family history of HL or deafness (in particular within young age), consanguinity, progressive HL
screening vs. diagnostic
screening - identity’s people with a high risk of having a specific genetic disorder
diagnostic - confirm or exclude a known/suspected genetic disorder
genetic testing involves …
detailed clinical and family history and a comprehensive examination of the patient and family if necessary
process of diagnosing a child with HL
NBHS, confirmation of HL, getting a family history, ENT/audiology/genetic evaluation, then molecular testing if applicable
best way to genetically diagnose a child with HL
-testing for GJB2 due to it being the most common
-otoSCOPE (can test for 152 genes known to cause HL and other syndromes; genetic anomalies)
-fluorescence in situ hybridization (identifies chromosome structures ; chromosomal anomalies)
how to test for mitochondrial mutations
DNA sample for genetic testing can be obtained from any tissue
-families with a maternal line of inheritance, individuals from high risk families, individuals from high risk ethnic groups and all infants admitted to the NICU should be tested
what to do when diagnosing a child with HL
detailed family history, consider genetic etiology, rule out syndromic HL, DNA testing for GJB2/6 genes and temporal bone imaging to rule out EVA
