human genetics concepts and applications ninth edition ricki lewis copyright ©the mcgraw-hill...
TRANSCRIPT
![Page 1: Human Genetics Concepts and Applications Ninth Edition RICKI LEWIS Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display](https://reader036.vdocuments.us/reader036/viewer/2022070308/551c24a6550346ad4f8b5d09/html5/thumbnails/1.jpg)
Human GeneticsConcepts and Applications
Ninth Edition
RICKI LEWIS
Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display
PowerPoint® Lecture Outlines Prepared by Johnny El-Rady, University of South Florida
6 Matters of Sex
![Page 2: Human Genetics Concepts and Applications Ninth Edition RICKI LEWIS Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display](https://reader036.vdocuments.us/reader036/viewer/2022070308/551c24a6550346ad4f8b5d09/html5/thumbnails/2.jpg)
2
SEX Determination
Maleness or femaleness is determined at conception
Humans are monoecious: meaning that each person can make one type of gamete either eggs or sperm
Dioecious organisms can make both types of gametes in the same body
![Page 3: Human Genetics Concepts and Applications Ninth Edition RICKI LEWIS Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display](https://reader036.vdocuments.us/reader036/viewer/2022070308/551c24a6550346ad4f8b5d09/html5/thumbnails/3.jpg)
3
Sex Chromosomes Determine Gender
Human males are the heterogametic sex with different sex chromosomes, (XY)
Human females are the homogametic sex (XX)
In other species sex can be determined in many ways
- For example, in birds and snakes, males are homogametic (ZZ), while females are heterogametic (ZW)
![Page 4: Human Genetics Concepts and Applications Ninth Edition RICKI LEWIS Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display](https://reader036.vdocuments.us/reader036/viewer/2022070308/551c24a6550346ad4f8b5d09/html5/thumbnails/4.jpg)
4
In grasshoppers, the female contains 24 chromosomes and is XX while the male contains 23 chromosomes and is XO
![Page 5: Human Genetics Concepts and Applications Ninth Edition RICKI LEWIS Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display](https://reader036.vdocuments.us/reader036/viewer/2022070308/551c24a6550346ad4f8b5d09/html5/thumbnails/5.jpg)
5
X and Y Chromosomes
X chromosome
- Contains > 1,500 genes
- Larger than the Y chromosome
- Acts as a homolog to Y in males
Y chromosome
- Contains 231 genes
- Many DNA segments are palindromes and may destabilize DNA Figure 6.2
![Page 6: Human Genetics Concepts and Applications Ninth Edition RICKI LEWIS Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display](https://reader036.vdocuments.us/reader036/viewer/2022070308/551c24a6550346ad4f8b5d09/html5/thumbnails/6.jpg)
6
Anatomy of the Y Chromosome
Figure 6.3
Pseudoautosomal regions (PAR1 and PAR2)
- 5% of the chromosome
- Contains genes shared with X chromosome
Male specific region (MSY)
- 95% of the chromosome
- Contains majority of genes including SRY and AZF (needed for sperm production)
![Page 7: Human Genetics Concepts and Applications Ninth Edition RICKI LEWIS Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display](https://reader036.vdocuments.us/reader036/viewer/2022070308/551c24a6550346ad4f8b5d09/html5/thumbnails/7.jpg)
7
SRY Gene
Encodes a transcription factor protein
Controls the expression of other genes
Stimulates male development
Developing testes secrete anti-Mullerian hormone and destroy female structures
Testosterone and dihydrotesterone (DHT) are secreted and stimulate male structures
![Page 8: Human Genetics Concepts and Applications Ninth Edition RICKI LEWIS Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display](https://reader036.vdocuments.us/reader036/viewer/2022070308/551c24a6550346ad4f8b5d09/html5/thumbnails/8.jpg)
8
Abnormalities in Sexual Development
Pseudohermaphroditism = Presence of male and female structures but at different stages of life
- Androgen insensitivity syndrome = Lack of androgen receptors
- 5-alpha reductase deficiency = Absence of DHT
- Congenital adrenal hyperplasia = High levels of androgens
![Page 9: Human Genetics Concepts and Applications Ninth Edition RICKI LEWIS Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display](https://reader036.vdocuments.us/reader036/viewer/2022070308/551c24a6550346ad4f8b5d09/html5/thumbnails/9.jpg)
9
Abnormalities in Sexual Development
The degree to which pseudohermaphroditism disturbs the individual depends as much on society as it does on genetics.
In the Dominican Republic in the 1970s, 22 young girls reached the age of puberty and began to transform into boys.
![Page 10: Human Genetics Concepts and Applications Ninth Edition RICKI LEWIS Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display](https://reader036.vdocuments.us/reader036/viewer/2022070308/551c24a6550346ad4f8b5d09/html5/thumbnails/10.jpg)
10
Abnormalities in Sexual Development
They had a form of 5-alpha reductase deficiency that was fairly common due to consanguinity ( relatives having children with relatives).
The parents were happy that they had had sons after all, and so these special adolescents were given their own gender nave at age 12.
![Page 11: Human Genetics Concepts and Applications Ninth Edition RICKI LEWIS Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display](https://reader036.vdocuments.us/reader036/viewer/2022070308/551c24a6550346ad4f8b5d09/html5/thumbnails/11.jpg)
11Figure 6.4
Figure 6.4
![Page 12: Human Genetics Concepts and Applications Ninth Edition RICKI LEWIS Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display](https://reader036.vdocuments.us/reader036/viewer/2022070308/551c24a6550346ad4f8b5d09/html5/thumbnails/12.jpg)
12
Table 6.1
![Page 13: Human Genetics Concepts and Applications Ninth Edition RICKI LEWIS Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display](https://reader036.vdocuments.us/reader036/viewer/2022070308/551c24a6550346ad4f8b5d09/html5/thumbnails/13.jpg)
13
Sex Ratios
The proportion of males to females in a human population
Calculated by # of males / # of females multiplied by 1,000
Primary sex ratio – At conception
Secondary sex ratio – At birth
Tertiary sex ratio – At maturity
Sex ratios can change markedly with age
![Page 14: Human Genetics Concepts and Applications Ninth Edition RICKI LEWIS Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display](https://reader036.vdocuments.us/reader036/viewer/2022070308/551c24a6550346ad4f8b5d09/html5/thumbnails/14.jpg)
14
Sex Ratios
Sex ratios can be altered intentionally by a society
- Example: China’s one-child policy has led to a scarcity of females
Figure 6.5
![Page 15: Human Genetics Concepts and Applications Ninth Edition RICKI LEWIS Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display](https://reader036.vdocuments.us/reader036/viewer/2022070308/551c24a6550346ad4f8b5d09/html5/thumbnails/15.jpg)
15
In China by the year 2020, 20 million men will find themselves without female partners as a result of the nations “ one-child” policy
The average number of births per woman fell from 5.4 in 1971 to 1.8 in 2001.
There is about 117 boys born for every 100 girls.The Chinese government is now promoting a “Care for Girls” program
which awards housing subsidies and scholarships to families with children
![Page 16: Human Genetics Concepts and Applications Ninth Edition RICKI LEWIS Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display](https://reader036.vdocuments.us/reader036/viewer/2022070308/551c24a6550346ad4f8b5d09/html5/thumbnails/16.jpg)
16
At the other end of the human life cycle, sex ratio favors females in most populations.
For people over the age of 65 in the United States there is a ratio of 75 men for every 100 women
![Page 17: Human Genetics Concepts and Applications Ninth Edition RICKI LEWIS Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display](https://reader036.vdocuments.us/reader036/viewer/2022070308/551c24a6550346ad4f8b5d09/html5/thumbnails/17.jpg)
17Figure 6.6
Sex Determination in Humans
Figure 6.6
![Page 18: Human Genetics Concepts and Applications Ninth Edition RICKI LEWIS Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display](https://reader036.vdocuments.us/reader036/viewer/2022070308/551c24a6550346ad4f8b5d09/html5/thumbnails/18.jpg)
18
Inheritance related to sex
Genes located exclusively on the x chromosome are called sex-linked
Genes that occur only on the Y chromosome can produce their effects only in males and are called Holandric genes
The mechanisms where a given trait is limited to one sex is called sex-limited and fi dominance of a given allele depends on the sex of the bearer is called sex-influenced.
![Page 19: Human Genetics Concepts and Applications Ninth Edition RICKI LEWIS Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display](https://reader036.vdocuments.us/reader036/viewer/2022070308/551c24a6550346ad4f8b5d09/html5/thumbnails/19.jpg)
19
Y-linked Traits
Genes on the Y chromosome are said to be Y-linked
Y-linked traits are very rare
Transmitted from male to male
No affected females
Currently, identified Y-linked traits involve infertility and are not transmitted
![Page 20: Human Genetics Concepts and Applications Ninth Edition RICKI LEWIS Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display](https://reader036.vdocuments.us/reader036/viewer/2022070308/551c24a6550346ad4f8b5d09/html5/thumbnails/20.jpg)
20
X-linked Traits ( we will do some examples on the board
Possible genotypes
X+X+ Homozyogus wild-type female
X+Xm Heterozygous female carrier
XmXm Homozygous mutant female
X+Y Hemizygous wild-type male
XmY Hemizygous mutant male
![Page 21: Human Genetics Concepts and Applications Ninth Edition RICKI LEWIS Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display](https://reader036.vdocuments.us/reader036/viewer/2022070308/551c24a6550346ad4f8b5d09/html5/thumbnails/21.jpg)
21
X-linked Recessive Inheritance
![Page 22: Human Genetics Concepts and Applications Ninth Edition RICKI LEWIS Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display](https://reader036.vdocuments.us/reader036/viewer/2022070308/551c24a6550346ad4f8b5d09/html5/thumbnails/22.jpg)
22
X-linked Recessive Traits
Examples:
- Ichthyosis = Deficiency of an enzyme that removes cholesterol from skin
- Color-blindness = Inability to see red and green colors ( only about 0.4 % are girls)
- Hemophilia = Disorder of blood-clotting
![Page 23: Human Genetics Concepts and Applications Ninth Edition RICKI LEWIS Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display](https://reader036.vdocuments.us/reader036/viewer/2022070308/551c24a6550346ad4f8b5d09/html5/thumbnails/23.jpg)
23Figure 6.7
Figure 6.7
![Page 24: Human Genetics Concepts and Applications Ninth Edition RICKI LEWIS Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display](https://reader036.vdocuments.us/reader036/viewer/2022070308/551c24a6550346ad4f8b5d09/html5/thumbnails/24.jpg)
24Figure 6.8
Figure 6.8
![Page 25: Human Genetics Concepts and Applications Ninth Edition RICKI LEWIS Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display](https://reader036.vdocuments.us/reader036/viewer/2022070308/551c24a6550346ad4f8b5d09/html5/thumbnails/25.jpg)
25
X-linked Dominant Inheritance
![Page 26: Human Genetics Concepts and Applications Ninth Edition RICKI LEWIS Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display](https://reader036.vdocuments.us/reader036/viewer/2022070308/551c24a6550346ad4f8b5d09/html5/thumbnails/26.jpg)
26
X-linked Dominant Traits
Incontinentia pigmenti
A newborn girl with IP has yellow, pus filled vesicles on her limbs, the lesions become warty and eventually give way to brown splotches that remain for life
Figure 6.9
![Page 27: Human Genetics Concepts and Applications Ninth Edition RICKI LEWIS Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display](https://reader036.vdocuments.us/reader036/viewer/2022070308/551c24a6550346ad4f8b5d09/html5/thumbnails/27.jpg)
27
X-linked Dominant Traits
Congenital generalized hypertrichosis
Produces many extra hair follicles, and more denser more abundant upper body hair. An affected man would pass the trait to all his daughter, but non of his sons. Why?Figure 6.10
![Page 28: Human Genetics Concepts and Applications Ninth Edition RICKI LEWIS Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display](https://reader036.vdocuments.us/reader036/viewer/2022070308/551c24a6550346ad4f8b5d09/html5/thumbnails/28.jpg)
28
Solving Genetic Problems
Steps to follow:
1) Look at the inheritance pattern
2) Draw a pedigree
3) List genotypes and phenotypes and their probabilities
4) Assign genotypes and phenotypes
5) Determine how alleles separate into gametes
6) Use Punnett square to determine ratios
7) Repeat for next generation
![Page 29: Human Genetics Concepts and Applications Ninth Edition RICKI LEWIS Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display](https://reader036.vdocuments.us/reader036/viewer/2022070308/551c24a6550346ad4f8b5d09/html5/thumbnails/29.jpg)
29
Sex-Limited Traits
Traits that affect a structure or function occurring only in one sex
The gene may be autosomal or X-linked
Examples:
- Beard growth
- Milk production
- Preeclampsia in pregnancy
![Page 30: Human Genetics Concepts and Applications Ninth Edition RICKI LEWIS Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display](https://reader036.vdocuments.us/reader036/viewer/2022070308/551c24a6550346ad4f8b5d09/html5/thumbnails/30.jpg)
30
Sex-limited characteristics do some examples on board
Genotype male chickens female HH Hen feathered Hen feathered
Hh Hen feathered Hen feathered
hh cock-feathered Hen feathered
![Page 31: Human Genetics Concepts and Applications Ninth Edition RICKI LEWIS Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display](https://reader036.vdocuments.us/reader036/viewer/2022070308/551c24a6550346ad4f8b5d09/html5/thumbnails/31.jpg)
31
Sex-Influenced Traits
Traits in which the phenotype expressed by a heterozygote is influenced by sex
Allele is dominant in one sex but recessive in the other
Example:
- Pattern baldness in humans
- A heterozygous male is bald, but a heterozygous female is not
![Page 32: Human Genetics Concepts and Applications Ninth Edition RICKI LEWIS Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display](https://reader036.vdocuments.us/reader036/viewer/2022070308/551c24a6550346ad4f8b5d09/html5/thumbnails/32.jpg)
32
Sex influenced traits
Baldness: do some problems on the board
Genotype Men women
BB bald Bald
Bb bald not
bb not not
![Page 33: Human Genetics Concepts and Applications Ninth Edition RICKI LEWIS Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display](https://reader036.vdocuments.us/reader036/viewer/2022070308/551c24a6550346ad4f8b5d09/html5/thumbnails/33.jpg)
33
X Inactivation
Females have two alleles for X chromosome genes but males have only one
In mammals, X inactivation balances this inequality and one X chromosome is randomly inactivated in each cell
The inactivated X chromosome is called a Barr body
![Page 34: Human Genetics Concepts and Applications Ninth Edition RICKI LEWIS Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display](https://reader036.vdocuments.us/reader036/viewer/2022070308/551c24a6550346ad4f8b5d09/html5/thumbnails/34.jpg)
34
X Inactivation
X inactivation occurs early in prenatal development
It is an example of an epigenetic change
- An inherited change that does not alter the DNA base sequence
The XIST gene encodes an RNA that binds to and inactivates the X chromosome
![Page 35: Human Genetics Concepts and Applications Ninth Edition RICKI LEWIS Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display](https://reader036.vdocuments.us/reader036/viewer/2022070308/551c24a6550346ad4f8b5d09/html5/thumbnails/35.jpg)
35
Barr Bodies
Were discovered in 1940s in female cats but not male
Barr body is the inactive X chromosome in a female somatic cell,
![Page 36: Human Genetics Concepts and Applications Ninth Edition RICKI LEWIS Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display](https://reader036.vdocuments.us/reader036/viewer/2022070308/551c24a6550346ad4f8b5d09/html5/thumbnails/36.jpg)
36
![Page 37: Human Genetics Concepts and Applications Ninth Edition RICKI LEWIS Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display](https://reader036.vdocuments.us/reader036/viewer/2022070308/551c24a6550346ad4f8b5d09/html5/thumbnails/37.jpg)
37Figure 6.12Figure 6.11
![Page 38: Human Genetics Concepts and Applications Ninth Edition RICKI LEWIS Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display](https://reader036.vdocuments.us/reader036/viewer/2022070308/551c24a6550346ad4f8b5d09/html5/thumbnails/38.jpg)
38Figure 2.3
X Inactivation Animation
Please note that due to differing operating systems, some animations will not appear until the presentation is viewed in Presentation Mode (Slide Show view). You may see blank slides in the “Normal” or “Slide Sorter” views. All animations will appear after viewing in Presentation Mode and playing each animation. Most animations will require the latest version of the Flash Player, which is available at http://get.adobe.com/flashplayer.
![Page 39: Human Genetics Concepts and Applications Ninth Edition RICKI LEWIS Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display](https://reader036.vdocuments.us/reader036/viewer/2022070308/551c24a6550346ad4f8b5d09/html5/thumbnails/39.jpg)
39
X Inactivation
A female that expresses the phenotype corresponding to an X-linked gene is a manifesting heterozygote
X inactivation is obvious in calico cats
LOOK AT KEY ON HOW TO SOLVE THESE PROBLEMS
Figure 6.12
![Page 40: Human Genetics Concepts and Applications Ninth Edition RICKI LEWIS Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display](https://reader036.vdocuments.us/reader036/viewer/2022070308/551c24a6550346ad4f8b5d09/html5/thumbnails/40.jpg)
40
X inactivation
Theoretically, X inactivation evens out the sexes for expression of X-linked genes.
In actuality, a female may not be equivalent, in gene expression, to a male because she has two cell populations, where the male has only one
![Page 41: Human Genetics Concepts and Applications Ninth Edition RICKI LEWIS Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display](https://reader036.vdocuments.us/reader036/viewer/2022070308/551c24a6550346ad4f8b5d09/html5/thumbnails/41.jpg)
41
X inactivation
A situation in which being heterozygote for an X-linked gene is harmful is craniofrontonasal syndrome. Males and homzygous females have asymmetrical facial features
Heterozygous females have much more sever phenotypes with very abnormal faces resulting from abnormal fusing of skull bones
![Page 42: Human Genetics Concepts and Applications Ninth Edition RICKI LEWIS Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display](https://reader036.vdocuments.us/reader036/viewer/2022070308/551c24a6550346ad4f8b5d09/html5/thumbnails/42.jpg)
42
Rett Syndrome: Curious inheritance pattern
Nearly always affects femalesOne symptom is that the girls do strange things with their hands__ uncontrollably taping objects, clapping , repeatedly put hands to mouth and wring their handsThis is dominant and in 99% of cases is not passed from parent to child but arises anew
![Page 43: Human Genetics Concepts and Applications Ninth Edition RICKI LEWIS Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display](https://reader036.vdocuments.us/reader036/viewer/2022070308/551c24a6550346ad4f8b5d09/html5/thumbnails/43.jpg)
43
Genomic Imprinting
The phenotype of an individual differs depending on the gene’s parental origin
Genes are imprinted by an epigenetic event: DNA methylation
- Methyl (CH3) groups bind to DNA and suppress gene expression in a pattern determined by the individual’s sex
![Page 44: Human Genetics Concepts and Applications Ninth Edition RICKI LEWIS Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display](https://reader036.vdocuments.us/reader036/viewer/2022070308/551c24a6550346ad4f8b5d09/html5/thumbnails/44.jpg)
44
Imprints are erased during meiosis
- Then reinstituted according to the sex of the individual
Figure 6.13
![Page 45: Human Genetics Concepts and Applications Ninth Edition RICKI LEWIS Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display](https://reader036.vdocuments.us/reader036/viewer/2022070308/551c24a6550346ad4f8b5d09/html5/thumbnails/45.jpg)
45
Importance of Genomic Imprinting
Function of imprinting isn’t well understood, but it may play a role in development
Research suggests that it takes two opposite sex parents to produce a healthy embryo
- Male genome controls placenta development
- Female genome controls embryo development
Genomic imprinting may also explain incomplete penetrance
![Page 46: Human Genetics Concepts and Applications Ninth Edition RICKI LEWIS Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display](https://reader036.vdocuments.us/reader036/viewer/2022070308/551c24a6550346ad4f8b5d09/html5/thumbnails/46.jpg)
46
Imprinting and Human Disease
Two distinct syndromes result from a small deletion in chromosome 15
- Prader-Willi syndrome
- Deletion inherited from father
- Angelman syndrome
- Deletion inherited from mother
The two syndromes may also result from uniparental disomy
![Page 47: Human Genetics Concepts and Applications Ninth Edition RICKI LEWIS Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display](https://reader036.vdocuments.us/reader036/viewer/2022070308/551c24a6550346ad4f8b5d09/html5/thumbnails/47.jpg)
47
Deletion on chromosome 15 reveals imprinting
Imprinting and Human Disease
Figure 6.16
![Page 48: Human Genetics Concepts and Applications Ninth Edition RICKI LEWIS Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display](https://reader036.vdocuments.us/reader036/viewer/2022070308/551c24a6550346ad4f8b5d09/html5/thumbnails/48.jpg)
48
![Page 49: Human Genetics Concepts and Applications Ninth Edition RICKI LEWIS Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display](https://reader036.vdocuments.us/reader036/viewer/2022070308/551c24a6550346ad4f8b5d09/html5/thumbnails/49.jpg)
49
Turner Syndrome
Called the XO syndrome
1 in 2,500 female births
99% of affected fetuses die in utero
Features include short stature, webbing at back of neck, incomplete sexual development (infertile), impaired hearing
Individuals who are mosaics may have children
No bar bodies in cells
![Page 50: Human Genetics Concepts and Applications Ninth Edition RICKI LEWIS Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display](https://reader036.vdocuments.us/reader036/viewer/2022070308/551c24a6550346ad4f8b5d09/html5/thumbnails/50.jpg)
50
XYY Syndrome
Also known as Jacobs syndrome
1 in 1,000 male births
96% are phenotypically normal
Modest phenotypes may include great height, acne, speech and reading disabilities
Studies suggesting increase in aggressive behaviors are not supported
![Page 51: Human Genetics Concepts and Applications Ninth Edition RICKI LEWIS Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display](https://reader036.vdocuments.us/reader036/viewer/2022070308/551c24a6550346ad4f8b5d09/html5/thumbnails/51.jpg)
51
Triplo-X
Called the XXX syndrome
1 in 1,000 female births
Few modest effects on phenotype include tallness, menstrual irregularities, and slight impact on intelligence
X-inactivation of two X chromosomes occurs and cells have two Barr bodies
May compensate for presence of extra X
![Page 52: Human Genetics Concepts and Applications Ninth Edition RICKI LEWIS Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display](https://reader036.vdocuments.us/reader036/viewer/2022070308/551c24a6550346ad4f8b5d09/html5/thumbnails/52.jpg)
52
Klinefelter Syndrome
Called the XXY syndrome
1 in 500 male births
Phenotypes include:
- Incomplete sexual development
- Rudimentary testes and prostate
- Long limbs, large hands and feet
- Some breast tissue development
Most common cause of male infertility
![Page 53: Human Genetics Concepts and Applications Ninth Edition RICKI LEWIS Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display](https://reader036.vdocuments.us/reader036/viewer/2022070308/551c24a6550346ad4f8b5d09/html5/thumbnails/53.jpg)
53
XXYY Syndrome
Likely arises due to unusual oocyte and sperm
Associated with more severe behavioral problems than Klinefelter syndrome
- AAD, obsessive compulsive disorder, learning disabilities
Individuals are infertile
Treated with testosterone
![Page 54: Human Genetics Concepts and Applications Ninth Edition RICKI LEWIS Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display](https://reader036.vdocuments.us/reader036/viewer/2022070308/551c24a6550346ad4f8b5d09/html5/thumbnails/54.jpg)
54
XYY Syndrome
Also known as Jacobs syndrome
1 in 1,000 male births
96% are phenotypically normal
Modest phenotypes may include great height, acne, speech and reading disabilities
Studies suggesting increase in aggressive behaviors are not supported