6092989
Description
Flashcards by Emma Allde, updated more than 1 year ago
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Created by Emma Allde
over 8 years ago
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| Question | Answer |
| Chromosomal abnormalities are responsible for ___% of spontaneous abortions; most of which are _______ | 50; trisomies |
| Why are trisomy 13, 18 and 21 the only autosomal trisomies to be born | Small chromosomes, so fewer genes in triplicate |
| What is Trisomy 13 called | Patau syndrome |
| What is the life expectancy of trisomy 13 | <1year ca. 103 days |
| What are the common abnormalities associated with Patau syndrome | heart defects, incomplete brain development, small or missing eyes, spinal defects, seizures |
| What is Trisomy 18 called | Edwards syndrome |
| What are the common abnormalities associated with Edwards syndrome | heart defects, heat defects, intestine protruding outside body, kidney malformations |
| What is the life expectancy of trisomy 18 | 18 - 95% die in utero 50% live to 2 months 5-10% will survive first year of life |
| What is the other name for Trisomy 21 | Down Syndrome |
| What serious disease/illness is associated with Trisomy 21 | acute leukaemia |
| At birth, babies with Down syndrome usually have certain characteristic signs, including: | flat facial features. small head and ears. short neck. bulging tongue. eyes that slant upward. oddly shaped ears. poor muscle tone. |
| What is the Simian crease | ○ This crease can be present of no consequence (1 in 30) ○ More likely in down syndrome |
| What is the cytogenetic nomenclature of Down Syndrome | 47, XX or XY |
| What is the life expectancy for Down syndrome | 50's (around 80%) |
| What is euploidy | The correct number of chromosomes |
| What is aneploidy | incorrect number of chromosomes |
| Aneploidy causes: | Failure of homologous chromosomes to separate during meiosis I |
| What errors happen during meiosis I to cause aneploidy | non-disjunction errors during oogenesis some cases of non-disjunction during spermatogenesis |
| What is the cytogenetic nomenclature of Klinefelter syndrome | 47, XXY |
| What are the key features of Klinefelter syndrome | • Can appear normal • Diagnosis usually made in late during adult life at the investigation of infertility • Limited development of secondary sex characteristics • Genetically male |
| What is the cytogenetic nomenclature of Turner Syndrome | 45, X |
| What is Turner's the only living example of | monosomy |
| What are the diagnostic features of Turner's syndrmoe | • Diagnosis sometimes made late during adulthood at the investigation of short stature or lack of period (amenorrhoea); no adolescent growth spurt; ova denerate in utero; limited development of secondary sexual characteristics |
| What is XYY syndrome | • Asymptomatic; • Increased growth velocity Above average height |
| What is XX male syndrome | Phenotypically male but infertile |
| How is an XX Male possible | Results from unequal combination of sex chromosomes resulting in a small tip of the Y being added on to the tip of the X This region of the Y bears the SRY (sex determining region of the Y) encoding the testis determining factor... initiates male sex determinations |
| What is the likelihood of an XX male | 1 in 20K male births |
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