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AD inheritance
| Term | Definition |
|---|---|
| Disease that affects every generation | Dominant |
| Disease affects mostly males | X linked |
| Father gave disease to son | Autosomal Dominant |
| All the daughters of a male affected are also affected | X linked dominant |
| Penetrance | the probability of individuals with a particular genotype manifesting with the condition |
| Expressivity | the extent of expression of a given genotype at the phenotypic level, e.g., the extent of disease manifestation |
| Example of Expressivity | Patients with Marfan syndrome present with highly variable manifestations of the disease |
| Pleiotropy | one gene contributes to multiple phenotypic effects, e.g., affects multiple organ systems |
| Examples or pleiotropy | phenylketonuria, Marfan syndrome, sickle cell disease |
| Compound heterozygosity | If the same gene on both chromosomes is altered due to differently mutated alleles, the affected gene may lose its function despite the mutation not being homozygous. |
| Anticipation | describes when a disease increases in severity over several generations or manifests earlier with each generation. Often occurs in trinucleotide repeat disorders |
| Example of Anticipation | Huntington disease |
| Allelic heterogeneity | Different mutations in the same allele result in the same phenotype. |
| Example of Allelic Heterogeneity | most single-gene related disorders, e.g., G6PD deficiency, familial hypercholesterolemia, β-thalassemia |
| Locus heterogeneity | Mutations in genes at different loci cause the same phenotype. |
| Examples of Allelic Heterogeneity | osteogenesis imperfecta, albinism |
| Autosomal Dominant Disorders | Achondroplasia, DiGeorge Syndrome, Familial Hypercholesterolemia, Huntington disease, Li-Fraumeni Syndrome, Malignant Hyperthermia, Myotonic Dystrophy, Neurofibromatosis Type I, Osteogenesis Imperfecta, Retinoblastoma, Von Hippel-Lindau Syndrome |
| NF1 | AD Neurofibromas (benign fleshy tumors) in the skin or, Café-au-lait spots , optic gliomas, lisch nodules, Scoliosis, sphenoid dysplasia HTN, renovascular, at Chromosome 17, Neurofibromin |
| About 50% cases are due to new mutations in | NF1 |
| Familial Hypercholesterolemia | AD cause of Coronary Heart Disease (CHD). A number of single gene forms (allelic heterogeneity). LDL receptor gene which recognizes apoprotein B-100 is mapped to chromosome 19. |
| Huntington Disease | AD due to CAG repeat expansion in the HD gene on chromosome 4. Causes damage in brain from accumulation of huntingtin protein. After 50 progressive dementia, and aggressive behavior, depression. elevated dopamine levels, and reduced GABA and acetylcholine |
| Osteogenesis Imperfecta (OI) | AD congenital disorder of type 1 collagen chromosome 17. Blue sclera. Curved bones. Brittle teeth |
| Von Hippel-Lindau syndrome | AD tumors arising in multiple organs hemangioblastomas, which are blood vessel tumors of the brain, spinal cord, and eye. chromosome 3. MutRenalCnsPancreatic |
| VHL gene provides instructions for | the VCB-CUL2 complex. This complex targets other proteins to be broken down (degraded) by the cell when they are no longer needed. |
| Tuberous Sclerosis | AD Mutation in either TSC1 or TSC2 Altered hamartin-tuberin complex Benign tumors (Hamartomas) |
| Polycystic kidney disease | AD in dominant chromosome 16 or 4 altered polycystin 1 or 2 gene onset in adulthood. bilateral flank masses |
| Cystic Fibrosis | AR. CFTR defect. bilateral flank masses |
| Commonest Mutation of CF in all ethnic groups is | a 3 bp deletion : Loss of phenylalanine residue at position 508 |
| Trypsinogen test for newborns or sweat test | used to test CF |
| TAY-SACHS DISEASE | (AR) Neurological degenerative disease. Severe mental retardation and physical deterioration. Onset during infancy (about 6 months) - death by 2 ~ 3 yrs. |
| mutation at the HEX A gene locus (Chromosome 15) ganglioside GM2, increases and degenerates central nervous system Cherry-red spot in the back of their eyes | Tay-sachs disease |
| Hemochromatosis | missense mutation (Cys282Tyr - replaces cysteine at position 282 with a tyrosine in the HFE gene) Disease caused by iron (hemosiderin) deposition hemosiderosis. Cirrhosis, Diabetes mellitus and skin pigmentation |
| testicular atrophy and increased risk of hepatocellular carcinoma. Ferritin hi, iron hi, TIBC low transferrin saturation, Late onset | Hemochromatosis |
| Alpha-1 Antitrypsin Defficiency | made mainly in the liver. Gets trapped and leads to liver disease. lack of Alpha-1 in the blood leads to lung disease |
Created by:
splashgreen
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