lecture chromsomes and human genetics fall 2013
DESCRIPTION
Chromosomes human geneticsTRANSCRIPT
![Page 1: Lecture Chromsomes and Human Genetics Fall 2013](https://reader034.vdocuments.mx/reader034/viewer/2022051411/5460baf7af79593a708b5523/html5/thumbnails/1.jpg)
Chromosomes andChromosomes andHuman GeneticsHuman Genetics
![Page 2: Lecture Chromsomes and Human Genetics Fall 2013](https://reader034.vdocuments.mx/reader034/viewer/2022051411/5460baf7af79593a708b5523/html5/thumbnails/2.jpg)
Chromosomes & Cancer Chromosomes & Cancer
• Some genes on chromosomes control Some genes on chromosomes control cell growth and divisioncell growth and division
• If something affects chromosome If something affects chromosome structure at or near these loci, cell structure at or near these loci, cell division may spiral out of controldivision may spiral out of control
• This can lead to cancerThis can lead to cancer
![Page 3: Lecture Chromsomes and Human Genetics Fall 2013](https://reader034.vdocuments.mx/reader034/viewer/2022051411/5460baf7af79593a708b5523/html5/thumbnails/3.jpg)
Philadelphia ChromosomePhiladelphia Chromosome
• First abnormal chromosome to be First abnormal chromosome to be
associated with a cancerassociated with a cancer
• Reciprocal translocationReciprocal translocation
• Causes chronic myelogenous Causes chronic myelogenous
leukemia (CML)leukemia (CML)
![Page 4: Lecture Chromsomes and Human Genetics Fall 2013](https://reader034.vdocuments.mx/reader034/viewer/2022051411/5460baf7af79593a708b5523/html5/thumbnails/4.jpg)
Genes Genes
• Units of information about heritable Units of information about heritable
traitstraits
• In eukaryotes, distributed among In eukaryotes, distributed among
chromosomeschromosomes
• Each has a particular locus Each has a particular locus – Location on a chromosomeLocation on a chromosome
![Page 5: Lecture Chromsomes and Human Genetics Fall 2013](https://reader034.vdocuments.mx/reader034/viewer/2022051411/5460baf7af79593a708b5523/html5/thumbnails/5.jpg)
Homologous Homologous ChromosomesChromosomes
• Homologous autosomes are Homologous autosomes are identical in length, size, shape, and identical in length, size, shape, and gene sequencegene sequence
• Sex chromosomes are nonidentical Sex chromosomes are nonidentical but still homologousbut still homologous
• Homologous chromosomes Homologous chromosomes interact, then segregate from one interact, then segregate from one another during meiosisanother during meiosis
![Page 6: Lecture Chromsomes and Human Genetics Fall 2013](https://reader034.vdocuments.mx/reader034/viewer/2022051411/5460baf7af79593a708b5523/html5/thumbnails/6.jpg)
AllelesAlleles
• Different molecular forms of a geneDifferent molecular forms of a gene
• Arise through mutationArise through mutation
• Diploid cell has a pair of alleles at Diploid cell has a pair of alleles at
each locuseach locus
• Alleles on homologous chromosomes Alleles on homologous chromosomes
may be same or differentmay be same or different
![Page 7: Lecture Chromsomes and Human Genetics Fall 2013](https://reader034.vdocuments.mx/reader034/viewer/2022051411/5460baf7af79593a708b5523/html5/thumbnails/7.jpg)
Sex ChromosomesSex Chromosomes
• Discovered in late 1800sDiscovered in late 1800s
• Mammals, fruit fliesMammals, fruit flies
– XX is female, XY is maleXX is female, XY is male
• In other groups XX is male, XY femaleIn other groups XX is male, XY female
• Human X and Y chromosomes function Human X and Y chromosomes function
as homologues during meiosisas homologues during meiosis
![Page 8: Lecture Chromsomes and Human Genetics Fall 2013](https://reader034.vdocuments.mx/reader034/viewer/2022051411/5460baf7af79593a708b5523/html5/thumbnails/8.jpg)
Karyotype Preparation - Karyotype Preparation - Stopping the Cycle Stopping the Cycle
• Cultured cells are arrested at Cultured cells are arrested at metaphase by adding colchicinemetaphase by adding colchicine
• This is when cells are most This is when cells are most condensed and easiest to identifycondensed and easiest to identify
![Page 9: Lecture Chromsomes and Human Genetics Fall 2013](https://reader034.vdocuments.mx/reader034/viewer/2022051411/5460baf7af79593a708b5523/html5/thumbnails/9.jpg)
Karyotype PreparationKaryotype Preparation
• Arrested cells are broken openArrested cells are broken open
• Metaphase chromosomes are Metaphase chromosomes are fixed and stainedfixed and stained
• Chromosomes are photographed Chromosomes are photographed through microscopethrough microscope
• Photograph of chromosomes is Photograph of chromosomes is cut up and arranged to form cut up and arranged to form karyotype diagramkaryotype diagram
![Page 10: Lecture Chromsomes and Human Genetics Fall 2013](https://reader034.vdocuments.mx/reader034/viewer/2022051411/5460baf7af79593a708b5523/html5/thumbnails/10.jpg)
1 2 3 4 5 6 7 8 9 10 11 12
13 14 15 16 17 18 19 20 21 22 XX (or XY)
Karyotype DiagramKaryotype Diagram
![Page 11: Lecture Chromsomes and Human Genetics Fall 2013](https://reader034.vdocuments.mx/reader034/viewer/2022051411/5460baf7af79593a708b5523/html5/thumbnails/11.jpg)
Sex Sex DeterminatioDetermination n
X
X Y
X
XX
XY
XX
XY
X X
Y
X
x
x
eggs sperm
female(XX)
male(XY)
![Page 12: Lecture Chromsomes and Human Genetics Fall 2013](https://reader034.vdocuments.mx/reader034/viewer/2022051411/5460baf7af79593a708b5523/html5/thumbnails/12.jpg)
The Y ChromosomeThe Y Chromosome
• Fewer than two dozen genes Fewer than two dozen genes
identifiedidentified
• One is the master gene for male sex One is the master gene for male sex
determination determination – SRY gene (sex-determining region of Y)SRY gene (sex-determining region of Y)
• SRY present, testes formSRY present, testes form
• SRY absent, ovaries formSRY absent, ovaries form
![Page 13: Lecture Chromsomes and Human Genetics Fall 2013](https://reader034.vdocuments.mx/reader034/viewer/2022051411/5460baf7af79593a708b5523/html5/thumbnails/13.jpg)
Effect of YEffect of YChromosomeChromosome
10 weeks
Y present
Y absent
7 weeks
birth approaching
appearance of structuresthat will give rise toexternal genitalia
appearance of “uncommitted” duct system
of embryo at 7 weeks
Y present
Yabsent
testis
ovary
testes ovaries
![Page 14: Lecture Chromsomes and Human Genetics Fall 2013](https://reader034.vdocuments.mx/reader034/viewer/2022051411/5460baf7af79593a708b5523/html5/thumbnails/14.jpg)
Androgen DeprivationAndrogen Deprivation
• The “Guevedoces” of the Dominican The “Guevedoces” of the Dominican RepublicRepublic
• Reports from isolated villages asserted Reports from isolated villages asserted that that ”children appearing to be ”children appearing to be girls turned into men at puberty.”girls turned into men at puberty.” (Urological Sciences Research (Urological Sciences Research Foundation)Foundation)
• http://www.usrf.org/news/010308-http://www.usrf.org/news/010308-guevedoces.htmlguevedoces.html
![Page 15: Lecture Chromsomes and Human Genetics Fall 2013](https://reader034.vdocuments.mx/reader034/viewer/2022051411/5460baf7af79593a708b5523/html5/thumbnails/15.jpg)
Male Pseudohermaphrodites Male Pseudohermaphrodites
• ““These children appeared to be girls These children appeared to be girls at birth, but at puberty these 'girls' at birth, but at puberty these 'girls' sprout muscles, testes, and a penis. sprout muscles, testes, and a penis. For the rest of their lives they are For the rest of their lives they are men in nearly all respects …. Their men in nearly all respects …. Their underlying pathology was found to underlying pathology was found to be a deficiency of the enzyme, 5-be a deficiency of the enzyme, 5-alpha Reductase. “alpha Reductase. “
![Page 16: Lecture Chromsomes and Human Genetics Fall 2013](https://reader034.vdocuments.mx/reader034/viewer/2022051411/5460baf7af79593a708b5523/html5/thumbnails/16.jpg)
MapMap
![Page 17: Lecture Chromsomes and Human Genetics Fall 2013](https://reader034.vdocuments.mx/reader034/viewer/2022051411/5460baf7af79593a708b5523/html5/thumbnails/17.jpg)
From the American Journal of From the American Journal of Medicine Medicine (Am. L. Med. 62: 170-191, 1977)(Am. L. Med. 62: 170-191, 1977)
![Page 18: Lecture Chromsomes and Human Genetics Fall 2013](https://reader034.vdocuments.mx/reader034/viewer/2022051411/5460baf7af79593a708b5523/html5/thumbnails/18.jpg)
From the American Journal of From the American Journal of Medicine Medicine (Am. L. Med. 62: 170-191, 1977)(Am. L. Med. 62: 170-191, 1977)
![Page 19: Lecture Chromsomes and Human Genetics Fall 2013](https://reader034.vdocuments.mx/reader034/viewer/2022051411/5460baf7af79593a708b5523/html5/thumbnails/19.jpg)
From the American Journal of From the American Journal of Medicine Medicine (Am. L. Med. 62: 170-191, 1977)(Am. L. Med. 62: 170-191, 1977)
• 6. And for the rest of their lives, the 6. And for the rest of their lives, the guevedoces resemble the other Dominican guevedoces resemble the other Dominican men in all respects except:men in all respects except:* Beard growth is scanty.* Beard growth is scanty.* There is no hairline recession.* There is no hairline recession.* None has acne.* None has acne.* The prostate remains small* The prostate remains small
![Page 20: Lecture Chromsomes and Human Genetics Fall 2013](https://reader034.vdocuments.mx/reader034/viewer/2022051411/5460baf7af79593a708b5523/html5/thumbnails/20.jpg)
The X ChromosomeThe X Chromosome
• Carries more than 2,300 genesCarries more than 2,300 genes
• Most genes deal with nonsexual Most genes deal with nonsexual traitstraits
• Genes on X chromosome can be Genes on X chromosome can be expressed in both males and femalesexpressed in both males and females
![Page 21: Lecture Chromsomes and Human Genetics Fall 2013](https://reader034.vdocuments.mx/reader034/viewer/2022051411/5460baf7af79593a708b5523/html5/thumbnails/21.jpg)
Genetic AbnormalityGenetic Abnormality
• A rare, uncommon version of a traitA rare, uncommon version of a trait
• PolydactylyPolydactyly
– Unusual number of toes or fingersUnusual number of toes or fingers
– Does not cause any health problemsDoes not cause any health problems
– View of trait as disfiguring is subjectiveView of trait as disfiguring is subjective
![Page 22: Lecture Chromsomes and Human Genetics Fall 2013](https://reader034.vdocuments.mx/reader034/viewer/2022051411/5460baf7af79593a708b5523/html5/thumbnails/22.jpg)
New Bond Girl Proud of New Bond Girl Proud of Her 'Little Oddity‘ Her 'Little Oddity‘ by Jonathan by Jonathan Crow | October 7 , 2008Crow | October 7 , 2008
“Gemma Arterton … has proven herself to be exceptional not only for her English Rose beauty, but also because she was born with six fingers on each hand.”
![Page 23: Lecture Chromsomes and Human Genetics Fall 2013](https://reader034.vdocuments.mx/reader034/viewer/2022051411/5460baf7af79593a708b5523/html5/thumbnails/23.jpg)
Genetic DisorderGenetic Disorder
• Inherited conditions that cause mild Inherited conditions that cause mild
to severe medical problemsto severe medical problems
• Why don’t they disappear?Why don’t they disappear?– Mutation introduces new rare allelesMutation introduces new rare alleles
– In heterozygotes, harmful allele is In heterozygotes, harmful allele is
masked, so it can still be passed on to masked, so it can still be passed on to
offspring offspring
![Page 24: Lecture Chromsomes and Human Genetics Fall 2013](https://reader034.vdocuments.mx/reader034/viewer/2022051411/5460baf7af79593a708b5523/html5/thumbnails/24.jpg)
Autosomal Recessive Autosomal Recessive Inheritance PatternsInheritance Patterns
• If parents are If parents are
both both
heterozygous, heterozygous,
child will have child will have
a 25% chance a 25% chance
of being of being
affected affected Figure 12.10aPage 204
![Page 25: Lecture Chromsomes and Human Genetics Fall 2013](https://reader034.vdocuments.mx/reader034/viewer/2022051411/5460baf7af79593a708b5523/html5/thumbnails/25.jpg)
GalactosemiaGalactosemia
• Caused by autosomal recessive alleleCaused by autosomal recessive allele
• Gene specifies a mutant enzyme in the Gene specifies a mutant enzyme in the pathway that breaks down lactosepathway that breaks down lactose
In-text figurePage 204
galactose-1-phosphate
enzyme 2
lactose galactose
enzyme 1
+glucose
galactose-1-phosphate
enzyme 3
intermediatein glycolysis
![Page 26: Lecture Chromsomes and Human Genetics Fall 2013](https://reader034.vdocuments.mx/reader034/viewer/2022051411/5460baf7af79593a708b5523/html5/thumbnails/26.jpg)
One Common Ancestor One Common Ancestor Behind Blue EyesBehind Blue Eyes• People with blue eyes have a single, People with blue eyes have a single,
common ancestor, according to new common ancestor, according to new research. research.
• A team of scientists has tracked down A team of scientists has tracked down a genetic mutation that leads to blue a genetic mutation that leads to blue eyes. The mutation occurred between eyes. The mutation occurred between 6,000 and 10,000 years ago. Before 6,000 and 10,000 years ago. Before then, there were no blue eyes.then, there were no blue eyes.
• http://www.livescience.com/health/080131-blue-eyes.htmlhttp://www.livescience.com/health/080131-blue-eyes.html
![Page 27: Lecture Chromsomes and Human Genetics Fall 2013](https://reader034.vdocuments.mx/reader034/viewer/2022051411/5460baf7af79593a708b5523/html5/thumbnails/27.jpg)
from Beals et al., An Introduction to Anthropology, 1965
Percentage Frequency of Light Eyes in and Near Europe
![Page 28: Lecture Chromsomes and Human Genetics Fall 2013](https://reader034.vdocuments.mx/reader034/viewer/2022051411/5460baf7af79593a708b5523/html5/thumbnails/28.jpg)
Danish geneticist Hans Danish geneticist Hans Eiberg in the journal Eiberg in the journal Human Human GeneticsGenetics• ““Originally, Eiberg says, everyone in the Originally, Eiberg says, everyone in the
world had brown eyes. But the mutation world had brown eyes. But the mutation acts as a switch that shuts off the OCA2 acts as a switch that shuts off the OCA2 gene, which controls the eye's production gene, which controls the eye's production of melanin. Melanin is the pigment that of melanin. Melanin is the pigment that gives color to eyes and hair.”gives color to eyes and hair.”
• http://www.spiegel.de/international/http://www.spiegel.de/international/world/0,1518,532346,00.htmlworld/0,1518,532346,00.html
![Page 29: Lecture Chromsomes and Human Genetics Fall 2013](https://reader034.vdocuments.mx/reader034/viewer/2022051411/5460baf7af79593a708b5523/html5/thumbnails/29.jpg)
““Inbred Mutants”Inbred Mutants”
“Brad Pitt's squinting a bit in the light of the flashbulbs, but he has blue eyes. A new study suggests he shares a common ancestor with all the world's other blue-eyed denizens.”
Pitt, Diaz, and Sinatra
![Page 30: Lecture Chromsomes and Human Genetics Fall 2013](https://reader034.vdocuments.mx/reader034/viewer/2022051411/5460baf7af79593a708b5523/html5/thumbnails/30.jpg)
HeteroHeterochromiachromia
• Heterochromia is an ocular condition Heterochromia is an ocular condition in which one iris is a different color in which one iris is a different color from the other iris (complete from the other iris (complete heterochromia), or where the part of heterochromia), or where the part of one iris is a different color from the one iris is a different color from the remainder (partial heterochromia or remainder (partial heterochromia or sectoral heterochromia). sectoral heterochromia).
http://en.wikipedia.org/wiki/Eye_color
![Page 31: Lecture Chromsomes and Human Genetics Fall 2013](https://reader034.vdocuments.mx/reader034/viewer/2022051411/5460baf7af79593a708b5523/html5/thumbnails/31.jpg)
Complete and Sectoral Complete and Sectoral HeterochromiaHeterochromia
http://en.wikipedia.org/wiki/Eye_color
![Page 32: Lecture Chromsomes and Human Genetics Fall 2013](https://reader034.vdocuments.mx/reader034/viewer/2022051411/5460baf7af79593a708b5523/html5/thumbnails/32.jpg)
Causes of HeterochromiaCauses of Heterochromia
• Chimeras and Waardenburg Chimeras and Waardenburg syndromesyndrome
• Injury or medicationInjury or medication
![Page 33: Lecture Chromsomes and Human Genetics Fall 2013](https://reader034.vdocuments.mx/reader034/viewer/2022051411/5460baf7af79593a708b5523/html5/thumbnails/33.jpg)
DuplicationDuplication
• Gene sequence that is repeated Gene sequence that is repeated
several to hundreds of times several to hundreds of times
• Duplications occur in normal Duplications occur in normal
chromosomeschromosomes
• May have adaptive advantageMay have adaptive advantage– Useful mutations may occur in copyUseful mutations may occur in copy
![Page 34: Lecture Chromsomes and Human Genetics Fall 2013](https://reader034.vdocuments.mx/reader034/viewer/2022051411/5460baf7af79593a708b5523/html5/thumbnails/34.jpg)
DuplicationDuplication
normal chromosome
one segment repeated
three repeats
![Page 35: Lecture Chromsomes and Human Genetics Fall 2013](https://reader034.vdocuments.mx/reader034/viewer/2022051411/5460baf7af79593a708b5523/html5/thumbnails/35.jpg)
InversionInversion
A linear stretch of DNA is reversed A linear stretch of DNA is reversed
within the chromosomewithin the chromosome
segments G, H, I become inverted
In-text In-text figurefigurePage 206Page 206
![Page 36: Lecture Chromsomes and Human Genetics Fall 2013](https://reader034.vdocuments.mx/reader034/viewer/2022051411/5460baf7af79593a708b5523/html5/thumbnails/36.jpg)
TranslocationTranslocation
• A piece of one chromosome becomes A piece of one chromosome becomes attached to another nonhomologous attached to another nonhomologous chromosomechromosome
• Most are reciprocalMost are reciprocal
• Philadelphia chromosome arose from Philadelphia chromosome arose from a reciprocal translocation between a reciprocal translocation between chromosomes 9 and 22chromosomes 9 and 22
![Page 37: Lecture Chromsomes and Human Genetics Fall 2013](https://reader034.vdocuments.mx/reader034/viewer/2022051411/5460baf7af79593a708b5523/html5/thumbnails/37.jpg)
Philadelphia ChromosomePhiladelphia Chromosome
http://gslc.genetics.utah.edu/units/disorders/karyotype/reciprocal.cfm
![Page 38: Lecture Chromsomes and Human Genetics Fall 2013](https://reader034.vdocuments.mx/reader034/viewer/2022051411/5460baf7af79593a708b5523/html5/thumbnails/38.jpg)
Philadelphia KaryotypePhiladelphia Karyotype
http://gslc.genetics.utah.edu/units/disorders/karyotype/reciprocal.cfm
![Page 39: Lecture Chromsomes and Human Genetics Fall 2013](https://reader034.vdocuments.mx/reader034/viewer/2022051411/5460baf7af79593a708b5523/html5/thumbnails/39.jpg)
In-text figurePage 206
TranslocationTranslocation
one chromosome
a nonhomologouschromosome
nonreciprocal translocation
In-text In-text figurefigurePage 206Page 206
![Page 40: Lecture Chromsomes and Human Genetics Fall 2013](https://reader034.vdocuments.mx/reader034/viewer/2022051411/5460baf7af79593a708b5523/html5/thumbnails/40.jpg)
DeletionDeletion
• Loss of some segment of a chromosomeLoss of some segment of a chromosome
• Most are lethal or cause serious disorderMost are lethal or cause serious disorder
![Page 41: Lecture Chromsomes and Human Genetics Fall 2013](https://reader034.vdocuments.mx/reader034/viewer/2022051411/5460baf7af79593a708b5523/html5/thumbnails/41.jpg)
AneuploidyAneuploidy
• Individuals have one extra or Individuals have one extra or less chromosome less chromosome
• (2(2nn + 1 or 2 + 1 or 2nn - 1) - 1)
• Major cause of human Major cause of human reproductive failurereproductive failure
• Most human miscarriages are Most human miscarriages are aneuploids aneuploids
![Page 42: Lecture Chromsomes and Human Genetics Fall 2013](https://reader034.vdocuments.mx/reader034/viewer/2022051411/5460baf7af79593a708b5523/html5/thumbnails/42.jpg)
PolyploidyPolyploidy
• Individuals have three or more of Individuals have three or more of each type of chromosome (3each type of chromosome (3nn, 4, 4nn))
• Common in flowering plantsCommon in flowering plants
• Lethal for humansLethal for humans– 99% die before birth99% die before birth
– Newborns die soon after birthNewborns die soon after birth
![Page 43: Lecture Chromsomes and Human Genetics Fall 2013](https://reader034.vdocuments.mx/reader034/viewer/2022051411/5460baf7af79593a708b5523/html5/thumbnails/43.jpg)
NondisjunctionNondisjunction
n + 1
n + 1
n - 1
n - 1chromosome alignments at metaphase I
nondisjunction at anaphase I
alignments at metaphase II anaphase II
Figure 12.17Page 208
![Page 44: Lecture Chromsomes and Human Genetics Fall 2013](https://reader034.vdocuments.mx/reader034/viewer/2022051411/5460baf7af79593a708b5523/html5/thumbnails/44.jpg)
Down SyndromeDown Syndrome
• Trisomy of chromosome 21Trisomy of chromosome 21
• Mental impairment and a variety of Mental impairment and a variety of additional defectsadditional defects
• Can be detected before birthCan be detected before birth
• Risk of Down syndrome increases Risk of Down syndrome increases dramatically in mothers over age 35dramatically in mothers over age 35
![Page 45: Lecture Chromsomes and Human Genetics Fall 2013](https://reader034.vdocuments.mx/reader034/viewer/2022051411/5460baf7af79593a708b5523/html5/thumbnails/45.jpg)
Trisomy 21Trisomy 21
![Page 46: Lecture Chromsomes and Human Genetics Fall 2013](https://reader034.vdocuments.mx/reader034/viewer/2022051411/5460baf7af79593a708b5523/html5/thumbnails/46.jpg)
Non-disjunctionNon-disjunction
![Page 47: Lecture Chromsomes and Human Genetics Fall 2013](https://reader034.vdocuments.mx/reader034/viewer/2022051411/5460baf7af79593a708b5523/html5/thumbnails/47.jpg)
Karotype Trisomy 21Karotype Trisomy 21
![Page 48: Lecture Chromsomes and Human Genetics Fall 2013](https://reader034.vdocuments.mx/reader034/viewer/2022051411/5460baf7af79593a708b5523/html5/thumbnails/48.jpg)
Mother’s AgeMother’s Age
Age = 35
Incidence/100
0births
![Page 49: Lecture Chromsomes and Human Genetics Fall 2013](https://reader034.vdocuments.mx/reader034/viewer/2022051411/5460baf7af79593a708b5523/html5/thumbnails/49.jpg)
Boy with Down’s SyndromeBoy with Down’s Syndrome
![Page 50: Lecture Chromsomes and Human Genetics Fall 2013](https://reader034.vdocuments.mx/reader034/viewer/2022051411/5460baf7af79593a708b5523/html5/thumbnails/50.jpg)
Turner SyndromeTurner Syndrome
• Inheritance of only one X (XO)Inheritance of only one X (XO)
• 98% spontaneously aborted98% spontaneously aborted
• Survivors are short, infertile femalesSurvivors are short, infertile females– No functional ovariesNo functional ovaries
– Secondary sexual traits reducedSecondary sexual traits reduced
– May be treated with hormones, surgeryMay be treated with hormones, surgery
![Page 51: Lecture Chromsomes and Human Genetics Fall 2013](https://reader034.vdocuments.mx/reader034/viewer/2022051411/5460baf7af79593a708b5523/html5/thumbnails/51.jpg)
MonosomyMonosomy(Having only one X chromsome (Having only one X chromsome per cell)per cell)
![Page 52: Lecture Chromsomes and Human Genetics Fall 2013](https://reader034.vdocuments.mx/reader034/viewer/2022051411/5460baf7af79593a708b5523/html5/thumbnails/52.jpg)
Turner’s SyndromeTurner’s Syndrome
![Page 53: Lecture Chromsomes and Human Genetics Fall 2013](https://reader034.vdocuments.mx/reader034/viewer/2022051411/5460baf7af79593a708b5523/html5/thumbnails/53.jpg)
Klinefelter SyndromeKlinefelter Syndrome
• XXY conditionXXY condition
• Results mainly from nondisjunction in Results mainly from nondisjunction in mother (67%)mother (67%)
• Phenotype is tall malesPhenotype is tall males– Sterile or nearly soSterile or nearly so– Feminized traits (sparse facial hair, Feminized traits (sparse facial hair,
somewhat enlarged breasts)somewhat enlarged breasts)– Treated with testosterone injectionsTreated with testosterone injections
![Page 54: Lecture Chromsomes and Human Genetics Fall 2013](https://reader034.vdocuments.mx/reader034/viewer/2022051411/5460baf7af79593a708b5523/html5/thumbnails/54.jpg)
KlinefelterKlinefelter
http://www.tokyo-med.ac.jp/genet/index-e.htmo
![Page 55: Lecture Chromsomes and Human Genetics Fall 2013](https://reader034.vdocuments.mx/reader034/viewer/2022051411/5460baf7af79593a708b5523/html5/thumbnails/55.jpg)
XYY ConditionXYY Condition
• Taller than average malesTaller than average males
• Most otherwise phenotypically Most otherwise phenotypically normalnormal
• Some mentally impairedSome mentally impaired
• Once thought to be predisposed to Once thought to be predisposed to criminal behavior, but studies now criminal behavior, but studies now discreditdiscredit
![Page 56: Lecture Chromsomes and Human Genetics Fall 2013](https://reader034.vdocuments.mx/reader034/viewer/2022051411/5460baf7af79593a708b5523/html5/thumbnails/56.jpg)
Phenotypic TreatmentsPhenotypic Treatments
• Symptoms of many genetic disorders Symptoms of many genetic disorders
can be minimized or suppressed bycan be minimized or suppressed by– Dietary controlsDietary controls
– Adjustments to environmental Adjustments to environmental
conditionsconditions
– Surgery or hormonal treatmentsSurgery or hormonal treatments
![Page 57: Lecture Chromsomes and Human Genetics Fall 2013](https://reader034.vdocuments.mx/reader034/viewer/2022051411/5460baf7af79593a708b5523/html5/thumbnails/57.jpg)
Genetic ScreeningGenetic Screening
• Large-scale screening programs Large-scale screening programs detect affected persons detect affected persons
• Newborns in United States Newborns in United States routinely tested for PKUroutinely tested for PKU– Early detection allows dietary Early detection allows dietary
intervention and prevents brain intervention and prevents brain impairmentimpairment
![Page 58: Lecture Chromsomes and Human Genetics Fall 2013](https://reader034.vdocuments.mx/reader034/viewer/2022051411/5460baf7af79593a708b5523/html5/thumbnails/58.jpg)
Prenatal DiagnosisPrenatal Diagnosis
• AmniocentesisAmniocentesis
• Chorionic villus samplingChorionic villus sampling
• FetoscopyFetoscopy
• All methods have some risksAll methods have some risks
![Page 59: Lecture Chromsomes and Human Genetics Fall 2013](https://reader034.vdocuments.mx/reader034/viewer/2022051411/5460baf7af79593a708b5523/html5/thumbnails/59.jpg)
AmniocentesisAmniocentesis
![Page 60: Lecture Chromsomes and Human Genetics Fall 2013](https://reader034.vdocuments.mx/reader034/viewer/2022051411/5460baf7af79593a708b5523/html5/thumbnails/60.jpg)
Pedigree AnalysisPedigree Analysis
![Page 61: Lecture Chromsomes and Human Genetics Fall 2013](https://reader034.vdocuments.mx/reader034/viewer/2022051411/5460baf7af79593a708b5523/html5/thumbnails/61.jpg)
Preimplantation DiagnosisPreimplantation Diagnosis
• Used with in-vitro fertilizationUsed with in-vitro fertilization
• Mitotic divisions produce ball of 8 cellsMitotic divisions produce ball of 8 cells
• All cells have same genesAll cells have same genes
• One of the cells is removed and its genes One of the cells is removed and its genes
analyzedanalyzed
• If cell has no defects, the embryo is If cell has no defects, the embryo is
implanted in uterusimplanted in uterus
![Page 62: Lecture Chromsomes and Human Genetics Fall 2013](https://reader034.vdocuments.mx/reader034/viewer/2022051411/5460baf7af79593a708b5523/html5/thumbnails/62.jpg)
Preimplant DiagnosisPreimplant Diagnosis
http://www.layyous.com/book/book%20images/Untitled-196b.jpg