NU 545
Unit 7 Study Guide
Advanced Pathophysiology
University of South Alabama.
This document provides a focused
study guide
It summarizes key concepts, lecture highlights, and
exam-relevant material to support efficient last-minute
review. The guide is structured to help students
reinforce understanding, identify weak areas, and prepare
confidently for the assessment.
, Exam 7
Ch 4
Genes and Genetic
Down syndrome, Mental retardation, Recessive inheritance, Cystic fibrosis, Transcription,
Nondisjunction, Aneuploidy, Polyploidy, Translocation, Klinefelter syndrome, Turner syndrome,
Cri du chat, Recessive, Dominant traits, Penetrance, Expressivity, Dominance, Recessiveness
*Disorders caused by dominant and recessive traits
1) Specific chromosomal abnormality responsible for Down Syndrome (Ch. 4,
Pg. 144)
● Aneuploid cells are defined as those that do not contain a multiple of 23 chromosomes.
● An aneuploid cell containing 3 copies of one chromosome is said to be trisomic (termed
trisomy). Females have 3-X chromosomes in each cell. Most common
● Trisomy of the twenty-first chromosome is the autosome aneuploidy which causes Down
Syndrome
● The karyotype of down syndrome consists of 47 chromosomes and shows trisomy 21
● Robertsonian translocation involves the fusion of the long arm of chromosome 21 and develops
down syndrome.
2) Causes of mental retardation/intellectual disability (pg 146)
Chromosome abnormalities are the leading know cause of mental retardation.
● About 75% of individuals with spina bifida have secondary hydrocephalus, which sometimes in
turn produces mental retardation.
● Cri du chat Syndrome – disease caused by chromosomal deletion. Means “cry of the cat”
causing intellectual disability. Deletions- broken and loss DNA. Zygote has one chromosome
that’s normal and one with missing genes.
● Fragile X Syndrome – A fragile site (a number of areas on chromosomes develop microscopically
observable breaks and gaps when the cells are cultured in a folate-deficient medium) located on
the long arm of the X chromosome. Fragile X syndrome is the second most common genetic
cause of mental retardation (after Down Syndrome) effecting 1 in 4,000 males and 1 in 8,000
females. Caused by elevated number (>200) of repeated DNA sequences that are duplicated
● Phenylketonuria (PKU) genotype – child unable to metabolize amino acide. Affects infants. If
left untreated, abnormal metabolites of phenylalanine will begin to accumulate in the infant’s
brain and irreversible mental retardation will occur. By imposing dietary restrictions to limit the
intake of food containing phenylalanine, however, retardation can be prevented. Although the
child still has the PKU genotype (genes), a modification of the environment (in this case the
child’s diet) produces an outwardly normal phenotype (genes and environmental factors).
, ● Prader-Willi Syndrome – disease of imprinting. Inherited from the father. Associated with the
deletion of about 4 million base pairs (Mb) of the long arm of chromosome 15.
● Angelman Syndrome – Same 4-Mb deletion but inherited from the mother.
● Down Syndrome-Robertsonian translocation involves the fusion of the long arm of chromosome
21 and develops down syndrome.
● Wilms tumor
3) What gene abnormality causes cystic fibrosis? (Ch. 36, pg. 151/1380)
Ex-dd, homozygous. The CF gene encodes a protein product that forms chloride channels in the
membranes of specialized epithelial cells. Defective transport of chloride channels ions leads to a salt
imbalance that results in secretions of abnormally thick, dehydrated mucus.
The cystic fibrosis transmembrane conductance regulator (CFTCR) gene mutation results in the
abnormal expression of cystic fibrosis transmembrane conductance regulator (CFTCR) protein, which is a
cyclic adenosine mono-phosphate (cAMP)–activated chloride channel present on the surface of many
types of epithelial cell membranes, including those lining airways, bile ducts, the pancreas, sweat ducts,
and the vas deferens. Regulates chloride and sodium ion channels.
4) How is a recessive disease inherited? pages 151
Rare. Carriers can be high. Most common lethal in white children is cystic fibrosis. 1/25 carry a copy of an
allele causing CF. Individuals must be homozygous (dd-affected) for a recessive allele to express the
disease, the carriers are phenotypically normal. Recessive alleles are maintained in normal carriers,
survive from one generation to the next. Marriage between related individuals termed consanguinity
-“with blood” (rare) are often factors in producing recessive diseases. Ex-cystic fibrosis. Criteria for
autosomal recessive inherited-
Males and females are affected in equal proportions
Consanguinity is sometimes present
The disease is seen in siblings but usually not in their parents
On average, ¼ of the offspring of carrier parents will be affected.
How are genetic diseases inherited?
● Most genetic diseases affecting children are recessive, meaning the normally functioning gene
in a pair will override the abnormal one, if a normal gene is present.
What does it mean to be a carrier?
● A carrier is a healthy person who has one altered copy of a gene and one normally functioning
copy. Because carriers do not become ill, many families pass recessive gene mutations down
from generation to generation without ever knowing it.
*Recessive gene mutations are known as "autosomal recessive" if they occur on one of the 22 pairs of
non-sex chromosomes and "X-linked" if they occur on an X chromosome.
Autosomal recessive inheritance
, ● Autosomal recessive diseases occur when both parents are carriers of the same disease and
their child inherits an altered gene from each of them. Children of carrier parents have:
- A 25% chance of inheriting two altered genes and developing the disease.
- A 25% chance of inheriting two normally functioning genes.
- A 50% chance of inheriting only one altered gene and becoming a carrier.
X-linked recessive inheritance
● X-linked conditions like Fragile X syndrome occur when there is a gene mutation on the X
chromosome. An X-linked condition is usually inherited from a woman who is a carrier of the
condition. Carrier females have a working copy of a gene on one X chromosome and an altered
copy on the other.
● Women pass on one of their X chromosomes in each egg. When the X chromosome with the
mutation is passed on in an egg and a Y chromosome is passed on in a sperm, the resulting male
fetus will have the X-linked condition.
● Males with X-linked inheritance are generally affected and females are unaffected carriers.
However, X-linked inheritance is complex. Depending on the specific disease and mutation, an
affected boy may be symptom-free or a carrier girl may have mild symptoms
5) Characteristics of Klinefelter syndrome, Turner syndrome, Cri du chat
syndrome pg 145
→ Klinefeler syndrome(pg.145 ): Individuals with at least two X chromosomes and a Y chromosome in
each cell (47,XXXY). Because of the presence of a Y chromosome these individuals have male
appearance, but are usually sterile, about half develop female like breast (gynecomastia) small testes,
body hair is sparse, high pitched voice, elevated stature, moderate degree of mental impairment, taller
than average, 10-15pt reduction in IQ. 1 in 1000 male births. 2/3 cases are caused by nondisjunction of
the X chromosomes in the mother and the frequency rises with maternal age. Individuals with 48, XXXY
and 49, XXXXY karyotype are considered to have Klinefeler syndrome and the degree of physical and
mental impairment increases with each X chromosome and have a male appearance. (Y chromosomes
causes undifferentiated gonads to become testes/always produces a male).
Extra Y chromosome -producing 47, XYY. Individuals with this karyotype tend to be taller than average,
have 10-15 point reduction in average IQ. This chromosome predispose affected individuals to violent,
criminal behavior/behavioral disorders.
→Turner Syndrome (page 145): The presence of a single X chromosome and no homologous X or Y
chromosome ( 45, X) , resulting in a total of 45 chromosomes. Inherited from the mother. Common
cause is loss of the parentally transmitted X chromosome. It’s a low aneuploidies in newborns.
Known as 45,X, and it causes a set of symptoms known as Turner syndrome. Because they have no Y
chromosome, only females are affected, usually sterile and have gonadal streaks rather than ovaries.
Streaks of connective tissue are susceptible to cancer in mosaics fetuses who have a Y chromosome.
Characteristic signs are short stature, female genitilia abnormality, webbed neck, shield-like chest with
underdeveloped breasts, coarctation (narrowing) of the aorta, and widely spaced nipples, and
imperfectly developed ovaries, edema of the feet in newborns, sparse body hair. Impairment of spatial
and math reasoning ability. IQ typically in normal range.
Teenagers treated with estrogen to development secondary sexual characteristics and avoid
osteoporosis (maintained at a reduced level). Human growth hormone administered to increase stature.
Unit 7 Study Guide
Advanced Pathophysiology
University of South Alabama.
This document provides a focused
study guide
It summarizes key concepts, lecture highlights, and
exam-relevant material to support efficient last-minute
review. The guide is structured to help students
reinforce understanding, identify weak areas, and prepare
confidently for the assessment.
, Exam 7
Ch 4
Genes and Genetic
Down syndrome, Mental retardation, Recessive inheritance, Cystic fibrosis, Transcription,
Nondisjunction, Aneuploidy, Polyploidy, Translocation, Klinefelter syndrome, Turner syndrome,
Cri du chat, Recessive, Dominant traits, Penetrance, Expressivity, Dominance, Recessiveness
*Disorders caused by dominant and recessive traits
1) Specific chromosomal abnormality responsible for Down Syndrome (Ch. 4,
Pg. 144)
● Aneuploid cells are defined as those that do not contain a multiple of 23 chromosomes.
● An aneuploid cell containing 3 copies of one chromosome is said to be trisomic (termed
trisomy). Females have 3-X chromosomes in each cell. Most common
● Trisomy of the twenty-first chromosome is the autosome aneuploidy which causes Down
Syndrome
● The karyotype of down syndrome consists of 47 chromosomes and shows trisomy 21
● Robertsonian translocation involves the fusion of the long arm of chromosome 21 and develops
down syndrome.
2) Causes of mental retardation/intellectual disability (pg 146)
Chromosome abnormalities are the leading know cause of mental retardation.
● About 75% of individuals with spina bifida have secondary hydrocephalus, which sometimes in
turn produces mental retardation.
● Cri du chat Syndrome – disease caused by chromosomal deletion. Means “cry of the cat”
causing intellectual disability. Deletions- broken and loss DNA. Zygote has one chromosome
that’s normal and one with missing genes.
● Fragile X Syndrome – A fragile site (a number of areas on chromosomes develop microscopically
observable breaks and gaps when the cells are cultured in a folate-deficient medium) located on
the long arm of the X chromosome. Fragile X syndrome is the second most common genetic
cause of mental retardation (after Down Syndrome) effecting 1 in 4,000 males and 1 in 8,000
females. Caused by elevated number (>200) of repeated DNA sequences that are duplicated
● Phenylketonuria (PKU) genotype – child unable to metabolize amino acide. Affects infants. If
left untreated, abnormal metabolites of phenylalanine will begin to accumulate in the infant’s
brain and irreversible mental retardation will occur. By imposing dietary restrictions to limit the
intake of food containing phenylalanine, however, retardation can be prevented. Although the
child still has the PKU genotype (genes), a modification of the environment (in this case the
child’s diet) produces an outwardly normal phenotype (genes and environmental factors).
, ● Prader-Willi Syndrome – disease of imprinting. Inherited from the father. Associated with the
deletion of about 4 million base pairs (Mb) of the long arm of chromosome 15.
● Angelman Syndrome – Same 4-Mb deletion but inherited from the mother.
● Down Syndrome-Robertsonian translocation involves the fusion of the long arm of chromosome
21 and develops down syndrome.
● Wilms tumor
3) What gene abnormality causes cystic fibrosis? (Ch. 36, pg. 151/1380)
Ex-dd, homozygous. The CF gene encodes a protein product that forms chloride channels in the
membranes of specialized epithelial cells. Defective transport of chloride channels ions leads to a salt
imbalance that results in secretions of abnormally thick, dehydrated mucus.
The cystic fibrosis transmembrane conductance regulator (CFTCR) gene mutation results in the
abnormal expression of cystic fibrosis transmembrane conductance regulator (CFTCR) protein, which is a
cyclic adenosine mono-phosphate (cAMP)–activated chloride channel present on the surface of many
types of epithelial cell membranes, including those lining airways, bile ducts, the pancreas, sweat ducts,
and the vas deferens. Regulates chloride and sodium ion channels.
4) How is a recessive disease inherited? pages 151
Rare. Carriers can be high. Most common lethal in white children is cystic fibrosis. 1/25 carry a copy of an
allele causing CF. Individuals must be homozygous (dd-affected) for a recessive allele to express the
disease, the carriers are phenotypically normal. Recessive alleles are maintained in normal carriers,
survive from one generation to the next. Marriage between related individuals termed consanguinity
-“with blood” (rare) are often factors in producing recessive diseases. Ex-cystic fibrosis. Criteria for
autosomal recessive inherited-
Males and females are affected in equal proportions
Consanguinity is sometimes present
The disease is seen in siblings but usually not in their parents
On average, ¼ of the offspring of carrier parents will be affected.
How are genetic diseases inherited?
● Most genetic diseases affecting children are recessive, meaning the normally functioning gene
in a pair will override the abnormal one, if a normal gene is present.
What does it mean to be a carrier?
● A carrier is a healthy person who has one altered copy of a gene and one normally functioning
copy. Because carriers do not become ill, many families pass recessive gene mutations down
from generation to generation without ever knowing it.
*Recessive gene mutations are known as "autosomal recessive" if they occur on one of the 22 pairs of
non-sex chromosomes and "X-linked" if they occur on an X chromosome.
Autosomal recessive inheritance
, ● Autosomal recessive diseases occur when both parents are carriers of the same disease and
their child inherits an altered gene from each of them. Children of carrier parents have:
- A 25% chance of inheriting two altered genes and developing the disease.
- A 25% chance of inheriting two normally functioning genes.
- A 50% chance of inheriting only one altered gene and becoming a carrier.
X-linked recessive inheritance
● X-linked conditions like Fragile X syndrome occur when there is a gene mutation on the X
chromosome. An X-linked condition is usually inherited from a woman who is a carrier of the
condition. Carrier females have a working copy of a gene on one X chromosome and an altered
copy on the other.
● Women pass on one of their X chromosomes in each egg. When the X chromosome with the
mutation is passed on in an egg and a Y chromosome is passed on in a sperm, the resulting male
fetus will have the X-linked condition.
● Males with X-linked inheritance are generally affected and females are unaffected carriers.
However, X-linked inheritance is complex. Depending on the specific disease and mutation, an
affected boy may be symptom-free or a carrier girl may have mild symptoms
5) Characteristics of Klinefelter syndrome, Turner syndrome, Cri du chat
syndrome pg 145
→ Klinefeler syndrome(pg.145 ): Individuals with at least two X chromosomes and a Y chromosome in
each cell (47,XXXY). Because of the presence of a Y chromosome these individuals have male
appearance, but are usually sterile, about half develop female like breast (gynecomastia) small testes,
body hair is sparse, high pitched voice, elevated stature, moderate degree of mental impairment, taller
than average, 10-15pt reduction in IQ. 1 in 1000 male births. 2/3 cases are caused by nondisjunction of
the X chromosomes in the mother and the frequency rises with maternal age. Individuals with 48, XXXY
and 49, XXXXY karyotype are considered to have Klinefeler syndrome and the degree of physical and
mental impairment increases with each X chromosome and have a male appearance. (Y chromosomes
causes undifferentiated gonads to become testes/always produces a male).
Extra Y chromosome -producing 47, XYY. Individuals with this karyotype tend to be taller than average,
have 10-15 point reduction in average IQ. This chromosome predispose affected individuals to violent,
criminal behavior/behavioral disorders.
→Turner Syndrome (page 145): The presence of a single X chromosome and no homologous X or Y
chromosome ( 45, X) , resulting in a total of 45 chromosomes. Inherited from the mother. Common
cause is loss of the parentally transmitted X chromosome. It’s a low aneuploidies in newborns.
Known as 45,X, and it causes a set of symptoms known as Turner syndrome. Because they have no Y
chromosome, only females are affected, usually sterile and have gonadal streaks rather than ovaries.
Streaks of connective tissue are susceptible to cancer in mosaics fetuses who have a Y chromosome.
Characteristic signs are short stature, female genitilia abnormality, webbed neck, shield-like chest with
underdeveloped breasts, coarctation (narrowing) of the aorta, and widely spaced nipples, and
imperfectly developed ovaries, edema of the feet in newborns, sparse body hair. Impairment of spatial
and math reasoning ability. IQ typically in normal range.
Teenagers treated with estrogen to development secondary sexual characteristics and avoid
osteoporosis (maintained at a reduced level). Human growth hormone administered to increase stature.
