Lecture 10

Question 1

What is mitochondrial inheritance?

Answer 1

idea that mitochondria contain their own genes and transcription takes place in the mitochondria independent of the nucleus

Question 2

Where is mitochondria located?

Answer 2

in the cytoplasm- only genetically passed by mom

Question 3

What disease does mutation in the mitochondrial DNA cause?

Answer 3

Leber’s hereditary optic neuropathy - progressive vision loss in 3rd decade of life

Question 4

What pattern does mitochondrial inheritance follow?

Answer 4

pattern of x-linked inheritance– common only in males

Question 5

What is uniparental disomy?

Answer 5

an individual inherits both homologs of a chromosomes pair from only one parent

Question 6

What did mendel’s experiment establish?

Answer 6

that the phenotupe is the same whether a given allele is inherited from the mom or dad

Question 7

define imprinting

Answer 7

the process of gene silencing when a normal individual has only one transcriptionally active copy of a gene

Question 8

What is an example of a disease due to imprinting?

Answer 8

Prader- Willi syndrome

Question 9

What is Prader-Willi Syndrome

Answer 9

deletion inherited from the father of chromosome 15

Question 10

Features of PWS?

Answer 10

short stature, hypotonia (poor muscle tone), small hands and feet, obesity, mild to moderate mental retardation, hypogonadism

Question 11

What symdrom develops when a child received the chromosome 15 deletion from mom?

Answer 11

Angelman syndrome

Question 12

Characteristics of Angelman syndrome?

Answer 12

severe mental retardation, seizures, ataxic gait, perpetually smiling facial expression

Question 13

What is Angelman’s syndrome?

Answer 13

a neuro-genetic disorder characterized by intellectual and developmental delay, sleep disturbance, jerky movements, “happy puppet syndrome”

Question 14

What is the most common genetic defect leading to Angelman’s syndrome

Answer 14

defect on chromosome 15 passed from mom

Question 15

What does someone look like who has hermaphroditism?

Answer 15

ambiguous genitals, ovarian and testicular tissues present in gonadal region

Question 16

What is the genotype of someone with Hermaphroditism?

Answer 16

genotype is 46XX and one X has genes of Y chromosome due to illegitimate crossing over during meiosis 1

Question 17

What is male pseudohermaphroditism due to?

Answer 17

androgen insensitivity- testicular feminization syndrome

Question 18

What is the genotype of someone with pseudohermaphroditism?

Answer 18

46 XY with ambiguous female genitalia

Question 19

Where are the testes located in someone with pseudohermaphroditism?

Answer 19

inguinal canal- vagina ends blindly without uterus and fallopian tubes

Question 20

WHat happens to the androgen receptors in pseudohermaphroditism?

Answer 20

absent in the target organs leading to blockage of masculinizing effect- coded by X chromosome, which has suffered deletion/point mutation

Question 21

Describe female pseudohermaphroditism

Answer 21

46XX, external genitalia are virilized so that they either resemble those of a normal male or are ambiguous

Question 22

WHat is the most common cause of female pseudohermaphroditism?

Answer 22

congenital adrenal hyperplasia- autosomal recessive

Question 23

What happens in congenital adrenal hyperplasia?

Answer 23

hormone synthesis switches from the manufacture or cortisol and aldosterone to the androgen pathway leading to striking virilization of a female fetus

Question 24

What are hemoglobinopathies?

Answer 24

disorders produced by abnormalities of hemoglobin structure

Question 25

What are the alpha and beta globin proteins in hemoglobinopathies?

Answer 25

the alpha and beta proteins contained in functional hemoglobin tetramers are derived from gene clusters- alpha is on chromosome 16 and beta is on chromosome 11

Question 26

What is Thalassemias the result of?

Answer 26

abnormalities in hemoglobin synthesis that affects both alpha and beta clusters

Question 27

Symptoms of Thalassemias?

Answer 27

anemia- fatigue, pallor, breathlessness

Question 28

What is thalassemia minor?

Answer 28

individuals heterozygous for B thalassemia have thalassemia minor

Question 29

What is thalassemia major?

Answer 29

in severe situation mutations in both maternal and paternal beta globin genes lead to loss of normal amount of beta globulin protein

Question 30

What is sickle cell disease due to?

Answer 30

abnormal HB- defective gene located on chromosome 11- mutated gene is HBA, autosomal recessive

Question 31

What is sickle cell disease caused by?

Answer 31

a point mutation in hemoglobin that causes abnormal shapes of fragile RBCs which may undergo hemolysis resulting in anemia

Question 32

What is heterozygote advantage?

Answer 32

when heterozygous individuals do not have symptoms and yet are resistant to malaria

Question 33

Symptoms of someone with sickle cell?

Answer 33

hemolytic anemia, vaso-oclusive process, splenic enlargement/infarction, aplastic crisis due to B 19 infection, all lead to shortened life span

Question 34

What is homocystinuria?

Answer 34

an autosomal recessive inherited disorder in which enzyme deficiency leads to defective metabolism of methionine

Question 35

What is homocystinuria characterized by?

Answer 35

accumulation of homocysteine in serum and increased excretion of homocysteine in urine

Question 36

What does homocysteinuria lead to?

Answer 36

multi systemic dosorder of the connective tissue, muscles, CNS, and cardiovascular system- infants appear normal

Question 37

What does someone with homocysteinuria look like?

Answer 37

tall, thin built, long limbs, high-arched feet, knock-knees, mental retardation, seizures

Question 38

Medication for someone with homocysteinuria

Answer 38

vitamin B6 diet, restriction of methionine in diet

Question 39

WHat is galactosemia?

Answer 39

a metabolic disorder that affects an individual's ability to metabolize the sugar galactose properly - autosomal recessive

Question 40

What does galactosemia result in?

Answer 40

enlarged liver, cirrhosis, renal failure, cataracts, brain damage, ovarian failure

Question 41

Treatment for galactosemia

Answer 41

eliminating lactose and galactose from diet

Question 42

What is phenylketonuria

Answer 42

deficiency of enzyme phenylalanine hydroxyls

Question 43

What is phenylalanine necessary for?

Answer 43

metabolizing the amino acid phenylalanine to the amino acid tyrosine which is essential for melanin formation.

Question 44

Where is PAH gene located?

Answer 44

chromosome 12

Question 45

What will someone with phenylketonuria look like?

Answer 45

may have blond hair, blue eyes, fair skin, musty odor in sweat and urine- if not treated they may develop microcephaly, mental retardation and seizures

Question 46

Who is phenylketonuria common in ?

Answer 46

caucasians of western europe

Question 47

How is PKU detected?

Answer 47

using the HPLC test/Guthrie test

Question 48

Treatment for PKU?

Answer 48

restriction of phenylalanine rich foods (meat, chicken, fish, eggs, nuts, cheese) and supplementing with starches- potatoes, bread, pasta, corn

Question 49

What is glucose-6-phosphate dehydrogenase deficiency?

Answer 49

X linked hereditary disease characterized by low levels of glucose 6-phosphate dehydrogenase

Question 50

Who is G6PD common in?

Answer 50

african, middle east and south asian populations

Question 51

What is a beneficial effect of G6PD?

Answer 51

protects against malaria

Question 52

What is the primary symptom of G6PD?

Answer 52

mostly asymptomatic- primary symptom is non-immune hemolytic anemia

Question 53

What is hemolysis caused by?

Answer 53

infection/by some drugs, antibiotics, anti-malarials/by eating broad beans

Question 54

SYmptoms in severe cases of G6PD?

Answer 54

hemolytic anemia, kernicteus, kidney damage

Question 55

What is alkaptonuria

Answer 55

inherited condition that causes urine to turn black when exposed to air

Question 56

What is the characteristic cause of alkaptonuria?

Answer 56

buildup of dark pigment in connective tissues and skin

Question 57

Characteristics of someone with alkaptonuria?

Answer 57

develop arthritis, particularly in spine and large joints

Question 58

Where is the mutation in alkaptonuria?

Answer 58

mutation of HGD gene- cause an enzyme deficiency which is involved in phenylalanine and tyrosine metabolism which results in accumulation of acid- autosomal recessive