Patterns Of Inheritance Flashcards
Normally appear with equal frequency in both sexes (unless penetrance differs in males and females)
AUTOSOMAL RECESSIVE
→ appear only when a person inherits two alleles for the trait, one from each parent
AUTOSOMAL RECESSIVE
[AUTOSOMAL RECESSIVE]
Whenever both parents are heterozygous, approximately _____________ of the offspring are expected to express trait, but this ratio will not be obvious unless the family is large.
1/4
When an affected person mates with
someone outside the family (aa x AA), usually
none of the children will display the trait,
although all will be carriers (heterozygous)
Autosomal Recessive
[Term]
Mating between closely related people is
called _________
consanguinity
[True or False]
In autosomal recessive:
Only when a person inherits two alleles for the trait, one from each parent
True
[Tay-Sachs Disease]
→ children with Tay-Sachs disease appear healthy at birth but become listless and weak at about what age?
6 months age
[Determine the Disease]
→ gradually, their physical and neurological conditions worsen, leading to blindness, deafness, and eventually death at 2 to 3 years of age
Tay-sachs disease
→ the disease results from the accumulation of a lipid called GM2 ganglioside in the brain
Tay-sachs disease
→ a normal component of brain cells, GM2 ganglioside is usually broken down by an enzyme called ___________________ but children with Tay-Sachs disease lack this enzyme
Hexosaminidase A
[Determine the Deficiency]
→ ↑ chylomicrons
→ increased chylomicrons lead to Familial Chylomicronemia
Lipoprotein Lipase Deficiency
→ increased chylomicrons lead to ___________________
Familial Chylomicronemia
→ significantly reduced levels of HighDensity Lipoprotein (HDL)
→ caused by lack of ABCA1 gene (can be found in chromosome 9)
Tangier’s Disease
[TANGIER’S DISEASE]
→ caused by lack of _________ gene (can be found in chromosome 9)
ABCA1 gene
appear in both sexes with equal frequency, and both sexes are capable of transmitting these traits to appear to their offspring
Autosomal DOminant
[TRUE OR FALSE]
Autosomal dominant traits do NOT skip generations
→ exceptions to this rule arise when people acquire the trait of a new mutation or when the trait has reduced penetrance
True
blood cholesterol is greatly elevated owing to a defect in cholesterol transport
Familial Hypercholesterolemia
→ ____________ is an essential component of cell membranes and is used in the synthesis of bile and salts and several hormones.
cholesterol
This disease is usually considered an autosomal dominant disorder because heterozygotes are deficient in LDL receptors
→ in these people, too little cholesterol is removed from the blood, leading to elevated blood levels of cholesterol and increased risk of coronary artery disease
Familial Hypercholesterolemia
Familial Hypercholesterolemia is due to a defect in the gene (located on human chromosome ____________ ) that normally codes for LDL receptor.
19
[TRUE OR FALSE]
→ people heterozygous for familial hypercholesterolemia have blood LDL levels that are twice normal and usually have heart attacks by the age of 45.
False, should be 35 years old
→ traits appear more frequently in males because males need inherit only a single copy of the allele to display the trait, whereas females must inherit two copies of the allele, one from each parent, to be affected
X-linked Recessive
→ tends to skip generation
→ traits are not passed from father to son, because a son inherits his father’s Y chromosome, not his X
X-linked recessive
→ also called CLASSICAL HEMOPHILIA
this disease results from the absence of a protein necessary for blood clot
Hemophilia A
[HEMOPHILIA A]
→ results from abnormal or missing factor __________, one of the proteins in the clotting cascade
Factor VIII
→ appear in males and females, although they often affect more females than males
→ males inherit an X-linked dominant trait only from his mother- the trait is not passed from father to son
X-Linked DOminant
→ a female on the other hand, inherits an X - chromosome from both her mother and father; so, females can receive an X-linked trait from either parent
X-linked Dominant
→ also called Familial Vitamin D-resistant rickets
Hypophosphatemia
→ people with this trait have features that superficially resemble those produced by rickets: bone deformities, stiff spine and joints, bowed legs, and mild growth deficiencies
Familial Vitamin D-resistant rickets
Classify: HYPOPHOSPHATEMIA
X-linked Dominant
Classify: HEMOPHILIA A
X-linked recessive
Classify: FAMILIAL HYPERCHOLESTROLEMIA
Autosomal dominant
Classify: Tangier’s Disease
Autosomal Recessive
Classify: Lipoprotein lipase deficiency
Autosomal Recessive
Classify: Tay-Sachs Disease
Autosomal Recessive
Classify: HYPERTRICHOSIS PINNAE AURIS
Y-linked Dominant
→ exhibit a specific, easily recognized pattern of inheritance
→ only males are affected, and the trait is passed from father to son
Y-LINKED DOMINANT
[True or False]
→ if a man is affected, all his male offsprings should also be affected
→ Y-linked traits do not skip generations
Both statements are true
- Appears in both sexes with equal frequency
- Traits tends to skip generations
- Affected offsprings are usually born to unaffected parents
- When both parents are heterozygous , approximately ¼ of the offsprings will be affected
- Appears more frequently among the children of consanguine marriages
Give the summary of main points for Autosomal Recessive
- Appears in both sexes with equal frequency
- Both sexes transmit the trait to their offspring
- Does not skip generation
- Affected offspring must have an affected parent, unless they possess a new mutation
- When one parent is affected (heterozygous) and the other parent is unaffected, approximately ½ of the offspring will be affected
- Unaffected parents do not transmit the trait
Give summary of main points for Autosomal Dominant
- More males than females are affected
- Affected sons are usually born to unaffected mothers; thus, the trait skip generations
- A carrier (heterozygous) mother produces approximately ½ affected sons
- Is never passed from father to son
- All daughters of affected fathers are carriers
Give summary for X-linked recessive
- Both males and females are affected; often more females than males are affected
- Does not skip generations. Affected sons must have an affected mother; affected daughters must have either an affected mother or affected father
- Affected fathers will pass that trait to their daughters
- Affected mothers (if heterozygous) will pass the trait on to ½ of their sons and ½ of their daughters
Give summary for X-Linked Dominant
- Only males are affected
- Is passed from father to ALL SONS
- Does not skip generation
Give summary for Y linked
