Genetics Lectures 29, 30, 31

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Lecture 29

Question Answer
First trimester testing performed between11 & 13 weeks
At what week can you start determining fetal sex15 Week (and up)
Second trimester testing performed between15 and 20 weeks.
At what week is Ultrasound performed in Non Invasive prenatal test performed to determine neural tube defects in a fetus18 weeks
By far, the leading indication for prenatal diagnosis isAdvanced Maternal Age
In the second trimester testing performed between 15 & 20 weeks, what would you find elevated which would be an indication for neural tube defectAFP
Assay the level of AFAFP (amniotic fluid alpha-fetoprotein), a fetal glycoprotein, in amniotic fluid for possible NTDs → AFP elevation is associated with an open NTD, as fetal AFP leaks from the open neural tube lesion into the amniotic fluid and then diffuses passively into maternal bloodAmniocentesis
Procedure of removing a sample of amniotic fluid transabdominally by syringe; usually performed the 15th to 16th week after the first day of the last menstrual periodAmniocentesis
In the first trimester testing performed between 11 & 13 weeks, what would you find elevated which would indicative of a trisomy (13, 18 or 21)β-hCG
The earliest invasive test that can be done for prenatal diagnosisChorionic Villus Sampling (Least Effective)
A sample of chorionic tissue is obtained transcervically (with a flexible cannula) or transabdominally (with a spinal needle), assisted by ultrasound imaging. Sample contains fetal trophoblastic cells used for DNA and chromosome analysis Usually performed between the 10th and 12th week of pregnancyChorionic Villus Sampling (Least Effective)
First-trimester screening-PAPP-A and free β-hCG are depressed below normal in all trisomies except β-hCG is elevated inDown syndrome
Second-trimester screening-MSAFP, free β-hCG , and unconjugated estriol (uE3) are measured in triple screen, or inhibin A is added for quadruple screen, all are depressed below normal in all trisomies except β-hCG and inhibin A are elevated inDown syndrome
The primary tool for diagnosing congenital heart defects.Echocardiograms
In an ultrasound using nuchal translucency (NT) what would you notice that would indicate a neural tube defectEdema
Noninvasive testing such as maternal serum screening analyzeFetal DNA circulating in maternal blood
Mutations in the TBX5 transcription factor gene.Holt-Oram Syndrome
Noninvasive testing involves screeningMaternal Serum
Noninvasive testing done in both the first-and second trimesters for prenatal testingMaternal Serum Screening
Non Invasive prenatal test performed at 16 weeks to determine neural tube defects in a fetusMaternal Serum Screen for Alpha-fetoprotein Assay (MSAFP)
AFP is usually found in fetus withNeural Tube Defects
Folic acid supplementation starting at least 1 month before conception and continuing through the first trimester reduces the incidence ofNeural Tube Defects (NTDs) by nearly 75%
Used to detect abnormalities in a fetus’s genes or chromosomes before birth-offered when there is an increased risk of having a child with a genetic condition due to mother’s age, family history, ethnicity, or ultrasound examPrenatal Testing
MSAFP, free β-hCG , and unconjugated estriol (uE3), inhibin A are measured inQuadruple Screen
MSAFP, free β-hCG , and unconjugated estriol (uE3) are measured inTriple Screen

Lecture 30 & 31

Question Answer
Mutated Ras proteins are constitutively _____ and result in uncontrolled cell growth such as is seen with bladder carcinomasActive
RET, MET & RAS GenesActivated Oncogenes
Which tumor do not invade or metastasizeAdenoma (Benign Tumors)
Which tumor is capable of invading surrounding tissue and metastasizing to other sites in the bodyAdenocarcinoma (Malignant Tumor)
BCL2 & TelomeraseAntiapoptotic Genes
FASApoptotic Genes
Cerebellar ataxia, telangiectases, immune deficiency, increased cancer incidence, chromosome instability, symptoms worsen with ageAtaxia-Telangiectasia
The normal function of the APC gene (Adenomatous polyposis coli) usually targets what oncogene for degradation which can activate C-Mycβ-Catenin
Growth deficiency, immunodeficiency, chromosome instability, and increased cancer incidenceBloom Syndrome
BRCA1 & BRCA2 Breast Cancer
B-cell tumor of the jaw common in children of equatorial Africa, is the result of a translocation between chromosomes 8 and 14, c-myc proto-oncogene on 8q24 translocated distal to the immunoglobulin heavy chain locus at 14q32Burkitt Lymphoma
t(8;14)Burkitt Lymphoma
Mutation in transcription factor MycBurkitt Lymphoma
C-myc gene (chr. 8) onto Ig Heavy chain locus (chr. 14)Burkitt lymphoma
Tumor that originate in epithelial tissue, such as cells lining the intestine, bronchi, or mammary ducts (most common)Carcinomas
What kind of genes are MSH2 & MLH1Caretaker Tumor Suppressor Genes (Hereditary Nonpolyposis Colon Cancer)
Act more indirectly by maintaining genome integrity and correcting mutations during DNA replication and cell division → include proteins involved in normal chromosome disjunction during mitosisCaretakers Tumor Suppressor Genes
Mutations in BCL-2Chronic Lymphocytic Leukemia
A form of leukemia characterized by the increased and unregulated growth of predominantly myeloid cells in the bone marrow and the accumulation of these cells in the bloodChronic Lymphocytic Leukemia
Formation of the Philadelphia chromosome translocation, t(9;22) leads toChronic Myelogenous Leukemia.
BCR (chr. 22)-ABL (chr. 9) fusion protein → constitutively active abl-kinase, leads to leukemiaChronic Myelogenous Leukemia
Mutation in cytoplasmic tyrosine kinase ABLChronic Myelogenous Leukemia
Mutations seen in at least 8 different loci including BRCA2, characterized by anemia, leukemia susceptibility, limb, kidney, and heart malformations, and chromosome instabilityFanconi Anemia
Autosomal dominant germline mutations in the both allele (2 hit) of the APC gene (Adenomatous polyposis coli)Familial Adenomatous Polyposis (FAP)
What kind of genes are RB1 & TP53Gatekeeper Tumor Suppressor Genes
Microsatellite instability can be found inHereditary Nonpolyposis Colon Cancer (HNPCC)
Inherited defects in DNA Mismatch Repair (MMR)Hereditary Nonpolyposis Colon Cancer (HNPCC)
MLH1, MSH2, and MSH6 being the most common (prototypical caretaker TSGs).Hereditary Nonpolyposis Colon Cancer (HNPCC)
Secondary mutations can occur in other TSGs including APC and the transforming growth factor β receptor II (TGFβR2) geneHereditary Nonpolyposis Colon Cancer (HNPCC)
Rb is active and regulates G1 to S Transition by inhibiting E2F therefore inhibiting gene expression in what formHypophosphorylated
Rb is Inactive and is NOT able to regulate G1 to S Transition by inhibiting E2F, which allows genes to be transcribed and active, in what formHyperphosphorylated
Directly regulate proto-oncogene function and include regulators of various cell-cycle checkpoints and mediators of programmed cell deathGatekeepers Tumor Suppressor Genes
Hereditary cancer syndrome (5% of all cancers)-the initial cancer-causing mutation is inherited through theGermline
Drug used to treat Chronic Myelogenous LeukemiaGleevec
A drug that sits in the ATP-binding pocket of the tyrosine kinase domain of the BRC-ABL fusion protein and prevents transfer of a phosphate group onto a tyrosine residue on a substrate protein.Gleevec
Cancers such as leukemia and lymphoma, spread throughout the bone marrow, lymphatic system, and peripheral bloodHematopoietic and Lymphoid Malignant Neoplasms
Mutations in the c-ras genes _______ the Ras GTPaseInactivate
Multiple "hits" to DNA are necessary to cause cancer. In children with inherited retinoblastoma, the first Rb1 mutation was inherited in the DNA, and any second mutation in the second allele would rapidly lead to cancer. In non-inherited retinoblastoma, two "hits" had to take place before a tumor could develop, explaining the difference in age of onset. This is an example ofKnudson's 2-hit Model of Carcinogenesis
Seen in rare “cancer families” → many different forms of cancer that affect a number of family members at an unusually early age due to a mutation in TP53Li-Fraumeni Syndrome
Gross chromosomal event that results in loss of the entire gene and the surrounding chromosomal region, leading to the "second hit" in a tumor suppressor gene leading to cancerLoss of Heterozygosity
What is bound to P53 causing it to be degraded and regulatedMdm2
Mutation in receptor tyrosine kinase Ret geneMultiple Endocrine Adenomatosis 2 (MEN2)
Proto-oncogene mutations seldom result in an inherited predisposition to cancer except for the example of activating mutations in the RET gene encoding a receptor tyrosine kinase leading toMultiple Endocrine Adenomatosis 2 (MEN2)
A disease process characterized by uncontrolled cellular proliferation leading to a tumorNeoplasia
Mutant allele of a proto-oncogene → facilitate transformation by stimulating proliferation or by inhibiting apoptosis. Have a dominant effect at the cellular level; a single mutant allele is sufficient to initiate the normal to malignant progressionOncogenes
Guardian of the GenomeP53
p53 is activated whenPhosphorylated
Rb1 gene defect, leading to Eye cancerRetinoblastoma
Tumor that has arisen in mesenchymal tissue, such as bone, muscle, connective tissue, or in nervous system tissueSarcomas
Sporadic (95% of all cancers) mutations occur in aSingle Somatic Cell (which divides and develops into a tumor)
Retinoblastoma "second hit" usually occurs in what cellsSomatic Cells
WT1gene defect, leading to Kidney cancerWilm’s Tumor
Skin cancers in sun-exposed areas, photosensitivity, cataracts, neurological abnormalitiesXeroderma Pigmentosum
Causes extreme sensitivity to UV radiation, severe freckling, severe sunburn and multiple skin cancers Xeroderma Pigmentosum
Lack of Nucleotide Excision RepairXeroderma Pigmentosum
UV light (pyrimidine dimmers) can’t be fixedXeroderma Pigmentosum