Genetics- General Principles Flashcards
Neurological comorbidities of Down Syndrome
- Intellectual disability
- Early onset Alzheimer Disease
Cardiac comorbidities of Down Syndrome
- Complete Atrioventricular Septal Defect
- VSD
- ASD
GI comorbidities of Down Syndrome?
- Duodenal Atresia (Double-bubble sign): occurs when a portion of the duodenum doesn’t form, resulting in blockage that stops food or fluid from leaving the baby’s stomach
- Hirschsprung Disease (Congenital Megacolon): Absences of ganglion cells in a segment of the bowel causing decreased peristalsis which results in loss of ability to move stool through the intestine.
Endocrine comorbidities of Down Syndrome?
- Hypothyroidism (High TSH, Low T4)
- Type 1 Diabetes Mellitus (Autoimmune reaction that destroys beta-cells in pancreas therefore causing decreased insulin production)
- Obesity
- Short Stature
Oncologist comorbidities of Down Syndrome?
Acute Leukemia
Orthopedic comorbidities of Down Syndrome?
Atlantoaxial instability: Excessive movement at the junction between the atlas (C1) and axis (C2) as a result of bony of ligamentous abnormality
Disease characterized by 45, XO
Turner’s Syndrome
(Remember they have Streak ovaries)
-Increased risk of Ovarian germ cell tumors
Disease characterized by 47, XXY
Klinefelter Syndrome (Tall, gynecomastia, small and firm testes, small penis, sparse pubic hair, abnormal body proportions like long legs and short trunk)
-Increased risk of extragonadal germ cell tumors
Homodimeric calcium-binding protein that is a marker for:
- Neural crest derivation (melanocytes and Schwann cells)
- Langerhans cells
- Dendritic cells
S-100
X-linked disorder characterized by easy bruising and excessive bleeding due to a deficiency in coagulation factor VIII
Hemophilia A
Location and function of enhancers?
Location: May be located upstream, downstream, or within introns of the gene
Function: Increase rate of transcription
Location and function of Silencers?
Location: May be located upstream, downstream, or within introns of the gene
Function: Decrease rate of transcription by binding repressor proteins
Location and function of the promoter region?
Location: 25 or 75 bases upstream from their associated genes
Function: Initiate transcription
Ribosome synthesis occurs primarily in what cell structure?
Nucleolus
Enzyme that repairs single-strand breaks in duplex DNA during DNA replication and repair?
DNA ligase
Enzyme that unwinds DNA at the replication fork
Helicase
Nuclear transcription factors that directly bind DNA via a leucine zipper motif
c-Jun and c-Fos
Percentage of expression in offspring for Autosomal dominant conditions when 1 parent is affected?
50%
- Huntington Disease
- Marfan Syndrome
- MEN
- Neurofibramatoses
- Achondroplasia (gain-of-function mutation in FGFR3 gene)
Percentage of expression in offspring of Autosomal Recessive conditions when both parents are carriers?
25% chance the child will have disease because of getting 2 alleles
75% chance child will have 1 or more allele (be careful cause questions can ask it this way)
- Cystic Fibrosis
- Hemochromatosis
- Sickle Cell Anemia
- Classical Galactosemia
Mutation resulting in a single base SUBSTITUTION that results in the placement of an incorrect amino acid in a protein sequence?
Missense Mutation
Mutation resulting from DELETION/addition of a number of bases not divisible by 3 in the coding region of a gene. This dramatically changes the protein structure and often results in the formation of a stop codon.
Frameshift Mutation
Mutation that introduces a premature stop codon in a coding region, resulting in the production of a truncated protein?
Non-sense Mutation
Mutation resulting from a single base substitution that does not change the amino acid. Has no effect on protein formation or function.
Silent Mutation
Important Mitochondrial Inherited Diseases?
- Leber Hereditary Optic Neuropathy: leads to bilateral vision loss
- Myoclonic Epilepsy: myoclonic seizures and myopathy associated with exercise. Skeletal muscle biopsy shows irregularly shaped muscle fibers (ragged red fibers)
- Mitochondrial encephalomyopathy: Presents with lactic acidosis and stroke-like episodes (MELAS)
