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59 Cards in this Set
- Front
- Back
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Why does Huntington's show up at an earlier age in successive generations of an affected pedigree?
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Anticipation. Successive generations add on CAG repeats, decreasing the probable age of onset.
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In whose gametes do CAG repeat expansions occur in Huntington's?
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Expansion in Huntington's occurs in PATERNAL meiosis
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What is the inheritance pattern of Huntington's?
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Autosomal Dominant
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What enzyme is deficient in PKU?
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Phenylalanine hydroxylase
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What's the inheritance patter of PKU?
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Autosomal recessive
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What is the natural history of PKU?
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Defects due to toxic phenylalalnine levels:
* neurotoxic * mental disability * seizures * “mousy” odor * hypopigmentation |
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What X-linked dystrophy is commonly used as an example of Lyonization?
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Duchenne's Muscular Dystrophy. Improbable skewing of X-inactivation will phenotypically display in women.
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Which parent provides the mutant allele in Prader-Willi?
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The father
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Which parent provides the mutant allele in Angelman's?
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The mother
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What's the classic phenotype for
Angelman's? |
Scissoring gait.
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What is the usual cause of Trisomy 21?
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Maternal non-disjunction in Meiosis 1 due to advanced maternal age.
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What phenomenon causes 50% of Turner's patients?
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X-chromosome deficiency due to PATERNAL nondisjunction
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What is the typical cause of Klinefelter's?
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Advanced maternal age.
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A mutation in what gene is responsible for Fragile X Syndrome?
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A mutation in the FMR1 gene at fragile sites, at the terminus of the long arm of the X chromosome.
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What is the inheritance pattern of Fragile X?
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X-Linked recessive, with high female penetrance due to Lionization.
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How is Fragile X assayed?
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By Souther Blot analysis
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What x-linked disorder is one of the most common causes of mental retardation?
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Fragile X Syndrome
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What group of CAG repeat disorders affects the spinal cord and cerebellum?
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Spinal Cerebellar Ataxia
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What's the inheritance pattern of spinal cerebellar ataxia?
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Autosomal dominant with Anticipation
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What two proteins are involved with early-onset Alzheimer's?
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1) Amyloid Precursor Protein
2) Presinilin |
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What protein is involved with late-onset Alzheimer's?
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Apolipoprotien E (Chromosome 19)
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What causes Myotonic Dystrophy?
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CTG expansions on chromosome 19
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What's the inheritance pattern for Myotonic Dystrophy?
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Autosomal dominant
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What's the most common cause of Duchenne Muscular Dystrophy?
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Affected individuals almost never father children, so 1/3 of incidence is from NEW MUTATIONS
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What's the classic sign associated with a DMD-affected boy?
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Gower's Sign - tripod push up to standing. Also enlarged calves.
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What's the test for DMD?
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Direct testing on a muscle biopsy for the dystrophin protein. (PCR and Southern also.)
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What are the main mutations for breast cancer? For ovarian cancer?
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Breast: BRCA1,2; Chk2; PTEN
Ovarian: p53, ATM, HNPCC |
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What's the cause for Fanconi Anemia?
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Fanconi Anemia is a genetically heterogeneous disease of DNA repair enzymes. BRCA2, ATM implicated.
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What gene is involved with Familial Adenomatous Polyposis?
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The APC gene, involved with cell cycle progression
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What gene is involved with Ataxia Telangiectasia?
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ATM: "Ataxia Telangiectasia Mutated"
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What types of genes are involved with Hereditary Nonpolyposis Colorectal Cancer?
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Genes involved in mismatch repair.
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What's the hallmark of HNPCC?
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Microsatellite instability
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How is HNPCC diagnosed?
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By Southern blot analysis
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What causes the majority of non-inherited, sporadic colon cancers?
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Microsatellite instability or APC mutation
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What's the cause of Maple Syrup Urine Disease?
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An deficiency of an enzyme responsible for the metabolism of branch chain amino acids.
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What are the Mucopolysaccaridoses?
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Lysosomal Storage Diseases; disorders of MPS lysosomal degradation.
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What causes Marfan Syndrome?
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Defect with the Fibrillin gene (FBN) on Chromosome 15
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What's the inheritance pattern for Marfan's?
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Autosomal dominant
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What's the inheritance pattern for Factor V Leiden?
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Autosomal dominant
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What's the inheritance pattern for Hemochromatosis?
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Autosomal recessive with variable expression and penetrance
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What's the inheritance pattern of Hemophilia A?
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X Linked Recessive. (Lyonization uncommon as most Factor VIII produced in the liver)
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What's the pathology of Osteogenesis Imperfecta?
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OI is a Type 1 collagen disorder, a.k.a. "Brittle Bone Disease"
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What's the inheritance pattern of OI?
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Autosomal dominant or post-zygotic germline mutation (Germline Mosaicism)
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What is the inheritance pattern of Rett's Disease?
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X-Linked Dominant. Occurs ONLY in girls (boys die in utero). Is nearly ALWAYS de novo.
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What's the inheritance pattern of Achondroplasia?
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Autosomal dominant, with 1/3 cases being de novo mutations.
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What's the molecular pathology behind Achondroplasia?
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FGFR3 mutation, causing a problem with cartilage growth.
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What is the natural history of Tay-Sachs Disease? Inheritance pattern?
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Neurodegenerative disease. Early childhood onset. Death before puberty. Autosomal recessive.
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What possible heterozygote advantage might Tay-Sachs disease convey?
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TB resistance
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What's the molecular pathology of Tay-Sachs?
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Loss of function mutation for neuraminidase gene. Can't breakdown sphingolipids, congested lysosomes.
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What's the molecular pathology of Chronic Myelogenous Leukemia?
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Reciprocal translocation between 9 & 22. Philadelphia chromosome.
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What is the inheritance pattern of Polycystic Kidney Disease?
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Autosomal dominant is the most common form.
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What is the natural history of ADPKD?
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ADPKD has a late onset with bilateral kidney involvement. It is a systemic disease as well, with cysts forming in the liver, pancreas and meninges. Aneurisms (esp. aortic) are common as well.
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What is the textbook example of variable expressivity?
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Waardenburg syndrome (PAX3 neural crest migration probs). Deafness and/or pigmentation problems are example symptoms.
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Name three MITOCHONDRIAL genetic diseases?
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1) MERRF
2) MELAS 3) Kearns-Sayre syndrome |
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What is Beckwith-Widermann Syndrome?
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A disorder associated with chromosomal IMPRINTING. BW infants are large, hypoglycemic, and predisposed to kidney tumors.
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What is the inheritance patter of McCune-Albright syndrome?
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Autosomal Dominant, Non-Viable
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Describe the genetics of McCune-Albight syndrome.
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Non-viable early in pregnancy. De novo mutation produces a mosaic distribution pattern. Multiple ectopic endocrine tumors result.
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What is the textbook spondyloarthropathy?
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Ankylosing Spondylitis.
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What are the shared characteristics of ankylosing spondylitis?
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* Mostly affects men
* Mostly affects HLA-B27 |
