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54 Cards in this Set
- Front
- Back
Aneuploidy is generally caused by...
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Maternal Non Disjunction
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What are symptoms of down's syndrome?
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hypotonia, rounded head with 3rd fontanelle, flat nasal bridge, protruding tongue, epicantric folds in eyes, single palmer crease in hands, congenital heart defects, 15-20% increased risk for having leukemia, increased risk for Alzheimer’s disease
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What are the causes of Down's syndrome?
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95% meiotic nondisjunction; 4% Robertsonian Translocation; 1% mitotic nondisjunction (higher functioning) – some cells are 46 chromosomes, some are 47 = mosaicism
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What is Edward's syndrome?
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Trisomy 18
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What are the clinical features of Edward's syndrome?
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reduced birth weight, hypertonia, distinctive hands (clenched and overlapping digits), rocker bottom feet, facial malformations (recessed chin/jaw, low set malformed ears, malformed heart, prominent occiput)
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What trisomy is Patau's Syndrome?
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Trisomy 13
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What are the clinical features of Patau's syndrome?
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CNS malformations, presence of single forebrain hemisphere/lobe, cleft lip/palate, microphtalmia – often blind, polydactyl, also has rocker bottom feet and clenched fist like Edward’s
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What is a Robertsonian Translocation?
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Fusion of long arms of 2 acrocentric chromosomes
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What are the common chromosomes associated with Robertsonian Translocation?
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Chromosomes 13, 14, 15, 21, 22 – 13q14q and 14q21q are common
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What cannot Array Comparative Genomic Hybridization detect?
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Cannot detect inversions or balanced rearrangements
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What is the usual cause of Sex Chromosome Disorders?
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Paternal Non Disjunction in Meiosis II
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What are clinical features of Klinefleter's XXY?
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tall, thin, long legs; at puberty – hypogonadism, underdeveloped secondary sex characteristic, gynecomastial (development of mammy gland), infertile, decrease verbal comprehension and ability
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What are the clinical features of Turner's Syndrome?
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webbed neck, lymphedema of hands and feet, short stature, infertile, severe cognition skills but IQ is average or above, deficiency in spatial perception and fine motor skills
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What's the treatment for Turner's syndrom?
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growth hormones and estrogen
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What is Camptomelic Dysplasia?
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Autosomal dominant disorder with lethal bone/cartilage malformations
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How can you be an XY female?
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Delete SRY
2 copies of DAX 1 1 copy of SOX 9 |
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How can you be an XX male?
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Presence of SRY on X due to recombination
2 copies of SOX 9 - an overproduction of SOX 9 causes a suppression of SRY |
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What is the most common defect in Congenital Adrenal Hyperplasia?
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Deficiency in 21 Hydroxylase - necessary for cortisol production.
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What are the causes for Male Pseudohermaphroditism?
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Deficiency 5-alpha reductase, Androgen Insensitivity Syndrome
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What are Paralogs?
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Genes expressed in the same region of the body such as A13 and D13
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What 3 HOX Genes mutations have been Identified?
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A1, A13, D13
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What are the phenotypes for A1 mutation?
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horizontal gaze and deafness, variable facial weakness, hypoventilation, vascular malformations, autism, no abducens cranial nerve and absence of inner ear structure
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What are the clinical features of a Sonic Headhog Mutation?
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Holoprosencephaly – failure of midface/forebrain to develop, single forebrain hemisphere, cleft lip/palate, hypotelorism (eyes close together)
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What is mutated in Type I and III of Wardenburg Shah Syndrome?
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PAX3
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Which form is the milder form of Wardenburg Shah Syndrome and what gene does it affect
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Type II - MITF
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What happens in a mutation of PAX 6?
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Aniridia = absense of iris
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What causes Rubenstein-Taybi Syndrome?
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Mutations in CBP, Can't Bind CREB, can't activate transcription
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What is the Phenotype of Rubenstein-Taybi?
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mental retardation, broad thumbs/toes, hirsutism (excessive hair), cryptoorhidism (undescended testes), congenital heart defects, downslanting palpebral fissure, hypoplastic maxilla, prominent nose
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What is a LOD Score?
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Z=log10 (likelihood data are linked at a given theta/likelihood data are unlinked, theta=.5)
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What are the significant values for LOD scores?
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Positive Z = suggestive of linkage
Z > 3 : 2 loci are linked Z<-2 : 2 loci are unlinked |
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What is the mutation in sickle cell anemia?
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mutation in Beta chain gene, Glutamine is changed to Valine, lose a restrictive enzyme site
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What is the problem with blood transfusion for people with Sickle Cell Anemia?
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Iron Overload
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What are thalassemias?
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decrease rate of synthesis/stability of one or more Hb Chains leading to imbalance in relative amounts of alpha and beta chain
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What is the phenotype of some one with PKU?
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mental retardation, eczema, hypopigmentation
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What are the 3 types of PKU?
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PKU, variant PKU and Non-PKU hyperphenylalanemia
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What was the most common underlying deficiency in children that had SIDS?
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MCAD - Fatty acid Disorder
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What is deficient in Tay-Sachs?
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hexosaminadase A
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What disorder is related to Cherry Red Spot?
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Tay-Sachs
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What are the symptoms of Cystic Fibrosis?
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malodorous stools, colic, “salty baby” chronic cough, frequent upper respiratory tract infections
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What is the test for CF?
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sweat chloride level. Normal 20mmol/L, CF = 75mmol/L
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What is Osteogenesis Imperfecta?
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brittle bone disease” - Problems with ossification; inherited disorder of type I collagen with wider range of clinical heterogeneity from lethal form to increase in fracture frequency
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List the types of OI in order from mildest to most severe
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Type I is mildest (usually loss of 1 chain) followed by III/IV and II is most devastating
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What is the repeating unit is a collagen chain?
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(Gly-X-Y), X is usually proline, and Y is hydroxyproline/hydroxylysine
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What is gene is mutated with Marfan's Syndrome?
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Fibrillin 1
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How do people with Marfan's Syndrome usually die?
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Cardiovascular Problems
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95% of Acondroplasiacs is due to what receptor?
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G380R
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What is one of the largest genes in the X chromosome?
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Dystrophin
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Why do people with hemophilia bleed a lot?
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Factors 8 and 9 play a role in converting prothrombin to thrombin which is involved in the final step in converting fibrinogen fibrin. Can’t create fibrin clot
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What enzyme is related to Fava Beans and what does this enzyme do?
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This is the 1st enzyme in hexose monophophate shunt that generates NADPH which detoxifies oxidants by generating reduced glutathione
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What is the deficiency in Lesch Nyan Syndrome?
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Deficiency in hypoxanthing guanine phosphoriboxyl transferase (HPRT) which is used as a feedback enzyme to shutdown puring production like adenosine and guanine
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What is genetic anticipation?
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As genes are passed down:
Age of onset of disorder decreases Severity increases Incidence of disease increases |
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What happens in Fragile X? As in what is the gene? Where is it located? And what does this cause?
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Fragile X mental retardation gene 1 – FMR1, CGG repeat in 5’ UTR
Hypermethlation causes transcriptional silencing, closed chromatin, RNA polymerase cannot access gene, no FMR1 made |
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What repeat causes Huntington's Disease?
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CAG
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Why are the symptoms of Myotonic Dysplasia?
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muscle hypoplasia, severe mental retardation, moderate facial weakness, myotonia, cataracts
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