Genetic Mutations
This first term refers to a non-pathologic change in DNA whereas the second term refers to a pathological change.
What is a genetic variant versus mutation?
This test is a low resolution cytogenetic technique using a microscope for visual assessment of the gross number and structure of chromosomes. It can be used to detect aneuploidy (changes in the number of chromosomes).
What is Karyotyping?
This aneuploidy is the most common genetic cause of intellectual disability.
What is Down Syndrome (Trisomy 21)
This term refers to the smallest possible variation in DNA.
What is a single nucleotide polymorphism (SNP)?
This genetic test can detect sub-microscopic sized Copy Number Variants (deletions and duplications) anywhere in the genome by sending hundreds to thousands of probes across the entire genome in a single test. This technique identifies a more precise estimate of the size of deletions and duplications.
What is Chromosomal microarray?
This is the most common trinucleotide repeat and a genetic condition known to be associated with Autism Spectrum Disorder.
What is Fragile X Syndrome?
This term describes a large number of base pair variations/mutations within the DNA.
What is Copy Number Variant (CNV)?
This genetic test reads every base pair throughout the entire genome including these protein-coding-regions and these other non-protein-coding regions of the genome.
What is whole genome sequencing, exons, and introns respectively?
This term describes a Copy Number Variant (CNV) that results in duplication or deletion of an entire chromosome.
(Bonus: This is the most common clinical example of a deletion of an entire chromosome)
What is aneuploidy?
(Bonus: What is Turner Syndrome = 45X?)
A genetic variant/mutation is considered "rare" when present in less then this percent of the population.
What is less then 1% of the population?
This is a cytogenetic test where a large fluorescent probe is directed towards a specific genetic region of interest and compared to a second probe which is directed to another part of the chromosome to be used as a control. (Hint: you need to know exactly where to look to find an abnormality using this test)
What is FISH (Fluorescence In Situ Hybridization)?
These two genetic tests are considered standard of care workup for a new diagnosis of autism spectrum disorder.
What are Fragile X test and Chromosomal Microarray?
This is the minimum number of base pair variations/mutations necessary for a Copy number variant to be detected.
What is equal to or greater then 1,000 base pairs?
Fragile X testing uses PCR or Southern Blot to detect this minimum number of this trinucleotide repeat on this gene of this chromosome.
What are greater then 200 CGG trinucleotide repeats of the FMR1 gene on the X chromosome?
This genetic disorder, caused by this mutation, results in a well established phenotype including dysmorphic facies, cardiac anomalies, hypocalcemia, and early onset psychosis.
What is DiGeorge syndrome (aka: Velocardiofacial syndrome)? It is caused by deletion of chromosome 22q11.2 and has a high association with schizophrenia.
Note: This disorder has variable expressivity: some individuals have minimal symptoms whereas others can be moderate to severe