Medical Genetics

Question 1

Aneuploidy

Answer 1

A missing or extra chromosome. (Diagnosed via CMA or Karyotype)

Question 2

Copy Number Variant

Answer 2

Gain or loss of several genes. AKA chromosomal deletions/duplications. (Diagnosed on CMA)

Question 3

Point Mutation

Answer 3

A genetic variant (single gene mutation) that causes disease (pathogenic)

Question 4

Benign Polymorphism

Answer 4

A genetic variant that does not cause disease (not pathogenic)

Question 5

Single Nucleotide Polymorphisms (SNPs)

Answer 5

Variations from the reference genome at a single nucleotide. May occur in coding or non-coding regions. May or may not be pathogenic (usually isn’t).

Question 6

Whole Genome Sequencing

Answer 6

Sequences the ENTIRE genome, including non-coding region. Detects Mendelian disease-causing variants.

Question 7

Whole Exome Sequencing

Answer 7

Sequences only the coding region of the genome (1%). Can detect most point mutations.

Question 8

Genome-Wide Association Studies (GWAS)

Answer 8

Research test used to “tease out” contribution of small genetic factors in multifactorial disease. Looks at SNPs across the whole genome. NOT used for polygenetic disease

Question 9

Multifactorial Disease vs Polygenetic Disease

Answer 9

Multiple SNPs AND the environment cause disease vs ONLY multiple SNPs cause disease

Question 10

Can Multifactorial or Polygenetic diseases be detected with genetic testing?

Answer 10

NO

Question 11

What do Karyotypes/Complete Microarrays (CMAs) test for?

Answer 11

Chromosomal disorders/ Aneuploidy

Question 12

What does DNA sequencing (with del/dup analysis) test for?

Answer 12

SNPs

Question 13

What does a Next Generation DNA Sequencing Panel test for?

Answer 13

A phenotype caused by many genes (ie. Cardiomyopathy is caused by 80+ genes)

Question 14

What does Whole Exome Sequencing test for?

Answer 14

Used to test phenotypes thought to be Mendelian, but no suspected singe gene OR for a limited differential of genes.

Question 15

Epigenetics

Answer 15

The study of how genes are EXPRESSED.

Question 16

Recurrence Risk

Answer 16

How likely a disease will reoccur in future generations of children birthed by disease-carrying parents. (3%) NOT MENDELIAN

Question 17

Mendelian Inheritance

Answer 17

RARE. Disease due to change in 1 gene. Most genetic diseases are non-mendelian.

Question 18

What type of tissues are affected in mitochondrial DNA mutations?

Answer 18

Tissues high in energy (ie. brain, heart, muscle)

Question 19

Haploinsufficiency

Answer 19

1 functional copy of a gene is lost leading to disease/abnormality.

Question 20

Types of Non-Mendelian Inheritance

Answer 20

1. Multifactorial
2. Mitochondrial
3. Complex Gene and Epigenetic DIsorders
4. Polygenetic

Question 21

Both types of inheritance (Mendel/Non-Mendel) can be tracked in a…

Answer 21

Family History Pedigree (Family Tree)

Question 22

Genotype-phenotype correlation

Answer 22

The relationship between the genes (genotype) and what is expressed (phenotype)

Question 23

The 3 causes of genetic mutations

Answer 23

1. Exposure to mutagenic agens
2. Inheritance
3. Spontaneous/De novo

Question 24

Main Types of Genetic Mutations:

Answer 24

1. Nonsense
2. Missense
3. Duplication
4. Deletion
5. Frameshift
6. Insertion

Question 25

General steps of DNA Replication (4)

Answer 25

1. Unwinding 2. Breaking apart at bases 3. Addition of new bases 4. Rewinding

Question 26

3 Steps of Transcription

Answer 26

1. Initiation 2. Elongation 3. Termination