Inheritance Patterns Flashcards
45,X describes what disease?
Turner Syndrome: Characteristic physical abnormalities, such as short stature, swelling, broad chest, low hairline, low-set ears, and webbed necks. Girls with Turner syndrome typically experience gonadal dysfunction (non-working ovaries), which results in amenorrhea (absence of menstrual cycle) and sterility. Concurrent health concerns are also frequently present, including congenital heart disease, hypothyroidism (reduced hormone secretion by the thyroid), diabetes, vision problems, hearing concerns, and many autoimmune diseases. Finally, a specific pattern of cognitive deficits is often observed, with particular difficulties in visuospatial, mathematical, and memory areas
47,XXY describes what disease?
Klinefelter Syndrome: Principal effects include hypogonadism and reduced fertility. A variety of other physical and behavioural differences and problems are common, though severity varies and many XXY boys have few detectable symptoms.
Familial polydactyly (having supernumerary fingers or toes) exhibits what type of inheritance?
Autosomal Dominant
Tuberous Sclerosis (a rare multi-system genetic disease that causes hamartomas to grow in the brain and on other vital organs) exhibits what type of inheritance?
Autosomal Dominant
Diagnosis of Tuberous Sclerosis (hamartomas in CNS and skin) can be complicated clinically by:
Variable Expression
Diagnosis of Tuberous Sclerosis (hamartomas in CNS and skin) can be complicated molecularly by:
Mosaicism (Somatic or Germline)
Neurofibromatosis 1 (A developmental syndrome caused by germline mutations in neurofibromin, a gene that is involved in the RAS pathway and causes tumors along the nervous system. NF-1 often comes with scoliosis (curvature of the spine), learning difficulties, eye problems, and epilepsy) exhibits what type of inheritance?
Autosomal Dominant
Marfan syndrome (a genetic disorder of the connective tissue. People with Marfan tend to be unusually tall, with long limbs and long, thin fingers) exhibits what type of inheritance?
Autosomal Dominant
Achondroplasia (a common cause of dwarfism) exhibits what type of inheritance?
Autosomal Dominant (It occurs as a sporadic mutation in approximately 75% of cases: associated with advanced paternal age)
Defects in what gene are responsible for Marfan Syndrome (a genetic disorder of the connective tissue)?
Fibrillin
Defects in the Fibrillin gene are associated with what disease?
Marfan Syndrome: A genetic disorder of the connective tissue. The most serious complications are defects of the heart valves and aorta. It may also affect the lungs, the eyes, the dural sac surrounding the spinal cord, the skeleton and the hard palate
Defects in the Fibrillin gene of what chromosome cause Marfan syndrome (a genetic disorder of the connective tissue)?
Chromosome 15q
Defects in what gene are responsible for Achondroplasia (a common cause of dwarfism)?
FGFR3
Defects in the FGFR3 gene are associated with what disease?
Achondroplasia: A common cause of dwarfism. The disorder itself is caused by a change in the DNA for fibroblast growth factor receptor 3 (FGFR3), which causes an abnormality of cartilage formation.
Defects in the FGFR3 gene of what chromosome cause Achondroplasia (a common cause of dwarfism)?
Chromosome 4p
What are some characteristics of Autosomal Dominant inheritance?
50% of offspring of affected individuals are affected. Equal numbers of males and females affected. Vertical transmission. Unaffected members of a family do not have affected children. Variable expression is common. Decreased penetrance is possible. Isolated cases likely due to new mutation
What are some characteristics of Autosomal Recessive inheritance?
Parents are asymptomatic carriers of the condition. 25% chance of recurrence in siblings. Equal number of males and females affected. Horizontal transmission. Consanguinity is possible, especially in very rare conditions
Cystic Fibrosis (abnormal transport of chloride and sodium across an epithelium, leading to thick, viscous secretions) exhibits what type of inheritance?
Autosomal Recessive
Thousands of deleterious mutations in the CFTR gene are associate with what disease?
Cystic Fibrosis: An autosomal recessive genetic disorder that affects most critically the lungs, and also the pancreas, liver, and intestine. It is characterized by abnormal transport of chloride and sodium across an epithelium, leading to thick, viscous secretions
Mutations in what gene are associated with Cystic Fibrosis (abnormal transport of chloride and sodium across an epithelium, leading to thick, viscous secretions)?
CFTR
What is the most common mutation in Cystic Fibrosis (abnormal transport of chloride and sodium across an epithelium, leading to thick, viscous secretions)?
Delta-F508
Phenylketonuria (nonfunctional phenylalanine hydroxylase, the enzyme necessary to metabolize phenylalanine to tyrosine. Phenylalanine accumulates and is converted into phenylpyruvate, which is detected in the urine) exhibits what type of inheritance?
Autosomal Recessive
An error in the gene for what protein is associated with Phenylketonuria (phenylpyruvate detected in the urine)?
Phenylalanine hydroxylase (metabolizes phenylalanine to tyrosine
What are some characteristics of X-linked inheritance?
Incidence in males much higher than females. Heterozygous females may express the condition depending on pattern of X inactivation. Carrier females: 50% of sons affected, 50% of daughters are carriers. Affected males: all sons unaffected, all daughters are carriers (no male to male transmission). Affected males are typically related through females. Isolated cases usually due to new mutation
Duchenne Muscular Dystrophy (muscle degeneration and eventual death) exhibits what type of inheritance?
X-linked (recessive)
What disease is characterized by a mutation in the dystrophin gene?
Duchenne Muscular Dystrophy: The absence of dystrophin permits excess calcium to penetrate the sarcolemma. Water enters into the mitochondria which then burst. Mitochondrial dysfunction amplifies the stress-induced cytosolic calcium signals and an amplification of stress-induced reactive-oxygen species production. Increased oxidative stress within the cell damages the sarcolemma and eventually results in the death of the cell. Muscle fibers undergo necrosis and are ultimately replaced with adipose and connective tissue.
Duchenne Muscular dystrophy (muscle degeneration and eventual death) is characterized by a mutation in what gene?
Dystrophin: Dystrophin is responsible for connecting the cytoskeleton of each muscle fiber to the underlying basal lamina (extracellular matrix) through a protein complex containing many subunits. The absence of dystrophin permits excess calcium to penetrate the sarcolemma. Water enters into the mitochondria which then burst. Mitochondrial dysfunction amplifies the stress-induced cytosolic calcium signals and an amplification of stress-induced reactive-oxygen species production.
Massively elevated Creatine Kinase levels at birth are common before the development of symptoms for what disease?
Duchenne Muscular Dystrophy: The absence of dystrophin permits excess calcium to penetrate the sarcolemma. Water enters into the mitochondria which then burst. Mitochondrial dysfunction amplifies the stress-induced cytosolic calcium signals and an amplification of stress-induced reactive-oxygen species production. Increased oxidative stress within the cell damages the sarcolemma and eventually results in the death of the cell. Muscle fibers undergo necrosis and are ultimately replaced with adipose and connective tissue.
The most common type of mental retardation in males results from what syndrome?
Fragile X Syndrome: The most widespread single-gene cause of autism and inherited cause of mental retardation among boys
What is the location of the fragile site in Fragile X Syndrome (single-gene cause of autism and inherited cause of mental retardation)?
Xq27
Premutation alleles of Fragile X Syndrome (single-gene cause of autism and inherited cause of mental retardation) commonly have what range of tandem repeats?
55-200 repeats
Premutation alleles of Fragile X Syndrome (single-gene cause of autism and inherited cause of mental retardation) in men and women may develop into what disorder?
Fragile X-associated tremor/ataxia syndrome. FXTAS
What are the odds of men with premutation alleles of Fragile X Syndrome (single-gene cause of autism and inherited cause of mental retardation) developing FXTAS after age 50?
1 in 3
Fragile X Syndrome (single-gene cause of autism and inherited cause of mental retardation) is characterized by a mutation in what gene?
FMR1
Fragile X Syndrome (single-gene cause of autism and inherited cause of mental retardation) is characterized by triplet repeat expansion. About how many repeats in the FMR1 gene?
>200 repeats
What is the “normal” amount of triplet repeats in an island of the genome?
Less than 40.
What is the main cause of mutation in the FMR1 gene that leads to Fragile X Syndrome (single-gene cause of autism and inherited cause of mental retardation)?
Triplet Repeat Expansions.
Myotonic Dystrophy (a chronic, slowly progressing, highly variable, inherited multisystemic disease characterized by wasting of the muscles, muscular dystrophy, cataracts, heart conduction defects, endocrine changes, and myotonia) demonstrates anticipation due to what type of disorder?
Triplet Repeat Expansions.
Many disorders caused by triplet repeat expansions show ________________?
Anticipation
Huntington Disease (a neurodegenerative genetic disorder that affects muscle coordination and leads to cognitive decline and psychiatric problems) exhibits what type of inheritance?
Autosomal Dominant
Huntington Disease (a neurodegenerative genetic disorder that affects muscle coordination and leads to cognitive decline and psychiatric problems) exhibits various onset. What are the approximate age of Adult onset HD?
About 40 years old
Huntington Disease (a neurodegenerative genetic disorder that affects muscle coordination and leads to cognitive decline and psychiatric problems) exhibits various onset. What is the age for Juvenile HD? Is Juvenile HD severe?
Under 20 years old. YES, very severe.
Huntington Disease (a neurodegenerative genetic disorder that affects muscle coordination and leads to cognitive decline and psychiatric problems) exhibits various onset. What is the approximate age for late onset HD? Is late onset HD severe?
Over 50 years old. NO, this is a milder form of disease.
Does the risk of Huntington Disease (a neurodegenerative genetic disorder that affects muscle coordination and leads to cognitive decline and psychiatric problems) decrease or increase with age?
Risk decreases as age increases.
Huntington Disease (a neurodegenerative genetic disorder that affects muscle coordination and leads to cognitive decline and psychiatric problems): CAG triplet repeat in Exon 1 encodes for what?
Polyglutamine tract (a portion of a protein consisting of a sequence of several glutamine units. A tract typically consists of about 10 to a few hundred such units)
Does the polyglutamine tract or the CAG repeat cause Huntington Disease (a neurodegenerative genetic disorder that affects muscle coordination and leads to cognitive decline and psychiatric problems)?
Polyglutamine tract (a portion of a protein consisting of a sequence of several glutamine units. A tract typically consists of about 10 to a few hundred such units)
Huntington Disease (a neurodegenerative genetic disorder that affects muscle coordination and leads to cognitive decline and psychiatric problems): The CAG repeat is unstable in the male or female germline?
Male
What are the genes involved in Prader-Willi Syndrome (low muscle tone, short stature, incomplete sexual development, cognitive disabilities, problem behaviors, and a chronic feeling of hunger that can lead to excessive eating and life-threatening obesity)?
snoRNA genes
Are the maternal or paternal snoRNA genes usually imprinted?
Maternal.
If the maternal snoRNA genes are imprinted and the paternal snoRNA genes are normally expressed, how will one get Prader-Willi Syndrome (low muscle tone, short stature, incomplete sexual development, cognitive disabilities, problem behaviors, and a chronic feeling of hunger that can lead to excessive eating and life-threatening obesity)?
If the normally expressed paternal snoRNA genes are deleted.
What is the gene responsible for Angelman syndrome?
UBE3A
Are the maternal or paternal UBE3A genes usually imprinted?
Paternal.
If the paternal UBE3A genes are imprinted and the maternal UBE3A genes are normally expressed, how will one get Angelman Syndrome (a neuro-genetic disorder characterized by severe intellectual and developmental disability, sleep disturbance, seizures, jerky movements - especially hand-flapping, frequent laughter or smiling, and usually a happy demeanor)?
If the normally expressed maternal UBE3A genes are deleted.
Prader-Willi Syndrome (mental retardation, hyperphagia, obesity, hypogonadism, and hypotonia) and Angelman Syndrome (a neuro-genetic disorder) are associated with deletions in the genes of what chromosome?
Chromosome 15
