Section 6 Flashcards
Genome
Organism’s genetic material
Gene
Set of nucleotides
Genes instruct for
Protein synthesis
Basic unit of inheritance
Gene
Allele
Alternative form of gene
Hereditary
Transmitted to offspring
Hereditary aka
Familial
Genetic
Perinatal
Last tri and 1st month after birth
Neonate
First 4 weeks
Infant
First year after birth
Congenital
Present at birth
4 categories of genetic disorders
- Single gene mutations
- Multifactorial inheritance
- Chromosomal abnormalities
- Atypical inheritance
8% of pediatric hospitalizations
Single gene disorders
3 types of single gene disorders
Autosomal dominant
Autosomal recessive
X-linked recessive
5 MC autosomal dominant disorders
- Familial hypercholesterolemia
- Polycystic kidney disease
- Hereditary spherocytosis
- Marfan syndrome
- Huntington syndrome
5 MC autosomal recessive disorders
- Sickle cell anemia
- Cystic fibrosis
- Tay-Sachs disease
- PKU
- Glycogen storage Disease
2 MC X-linked diseases
Duchesse muscular Dystrophy
Hemophilia A
Autosomal dominate has a ____ onset
Delayed
___ can cause spontaneous condition in regards to autosomal dominate disorders
Sporadic mutations
Autosomal dominant affects
Structural proteins
Membrane receptors
Autosomal dominant can display ____ and ____
Reduced penetrance
Variable expressivity
Reduced penetrance
Have mutation, but no physical manifestations
Variable expressivity
Same mutation expressed differently in individuals
Example of variable expressivity
Nevus vs cutaneous neurofibromas
Largest group of Mendelian disorders
Autosomal recessive
Autosomal recessive has ___ onset and ____
Early
Complete penetrance
Autosomal recessive is rarely
Sporadic
Autosomal recessive disrupts enzymes, causing
Altered metabolism
X-linked recessive, ___ are asymptomatic carriers and ___ have 50% chance of getting it
Females
Males
Multifactorial inheritance
Genetic + environmental risks
Marfan syndrome is
Autosomal dominant
Marfan syndrome results from mutation in ___ and is ____ familial and ___ sporadic
FBN1 mutation (fibrillin 1 gene)
85%
15%
Fibrillin
Structural glycoprotein made from fibroblasts
The disorder of fibrillin in marfan results in
Irregular CT
Bilateral lens subluxations aka
Ectopia lentis
Atlantoaxial instability and basilar invagination is observed in ____ patients with marfan syndome
30-50%
Wrist sign observed in Marfans
Thumb/index fingers overlap when wrapped around wrist
Steinberg Sign observed in Marfans
Adduction of thumb past 5th digit
Protrusio acetabuli observed in Marfans
Acetabulum protrudes medially
Thoracolumbar scoliosis observed in Marfans
> 20 degrees lateral curve
Dolichocephaly
Elongated face
Dural ectasia observed in Marfans
Scalloping of dorsal vertebral body due to widening of Spinal canal
60-90% of patients
Symptoms of Marfan’s Syndrome
- Ectopia lentis
- Ruptured aorta
- Floppy valve syndrome
- Atlantoaxial instability and basilar invagination
- Long limbs
- Arachnodactyly
- Pectus deformities
- Wrist sign
- Steinberg sign
- Protrusio acetabuli
- Pes planovalgus
- Dolichocephaly
- High arched dental palate
- Dural ectasia
Ehlers Danlos Syndrome is
Autosomal dominant
1/200,000
Ehlers danlos syndrome is a defect in ___, which decreases tensile strength
Collagen
Symptoms of ehlers danlos syndrome
Hyperextensible skin
Hyper mobile joints
Familial hypercholesterolemia is
Autosomal dominant
1/500
Heterozygous familial hypercholesterolemia is a ____ increase in LDL, and has a ___ onset
2-3X
Adulthood
Xanthomas
Cholesterol deposits on tendons
Homozygous familial hypercholesterolemia is a ___ increase in LDL and has a ___ onset
5X
Childhood
More serious, and often lethal, familial hypercholesterolemia
Homozygous
Familial hypercholesterolemia is due to a mutated
LDLR gene
Mutated LDLR gene causes impaired ___, which increases ____ and ____
LDL Transport and catabolism
LDL in plasma
Vascular deposits
Treatment for familial hypercholesterolemia
Statins
Lifestyle modifications
Cystic fibrosis is
Autosomal recessive
1/3200 Caucasians
____ is mutated in CF
CFTR gene
Mutated CFTR gene causes ____ Transport
Low Cl ion transport
Low Cl transport can result in
Viscous secretions
Salty sweat
MC cause of death in CF
Cor pulmonale
Cor pulmonale
R sided heart failure due to lungs
___ also common in CF
Pancreatic insufficiency
Males with CF can be infertile due to
Absent vas deferens
Chronic lung infections in CF due to
Low mucociliary clearance
Pancreatic insufficiency in CF due to
Ductal obstruction
Fibrillin is a component of
Microfibrils of ECM
Marfan’s syndrome most likely to affect 3 tissue types
Osseous skeletal tissue
Eyes
Cardiovascular tissue
Floppy valve syndrome MC in
Mitral valve
MC autosomal dominant Mendelian disorder
Familial hypercholesterolemia
Risks of familial hypercholesterolemia
Premature atherosclerotic plaques
Coronary artery disease
MI risk
Ductal obstruction in pancreas from CF prevents ___ resulting in ____
Pancreatic zymogens from reaching small intestine
Malabsorption
PKU is ____ and how common
Autosomal recessive
1/10,000
Main problem with PKU
Mutated phenylalanine hydroxylase
Can’t metabolize phenylalanine
People with PKU have light skin and hair pigmentation due to
Lack of tyrosine, which is precursor to melanin
Phenylalanine can be ___ if not metabolized
Neurotoxic
___ of people with PKU never talk, and ___ never walk
2/3
1/3
Maternal PKU
Mother with PKU must modify diet before conception to prevent microcephaly or cardiac malformations since phenylalanine crosses placenta and is teratogenic
Benign hyperphenylalanine
Modest PKU
No neurological damage
Alkaptonuria (AKU) aka
Black urine disease
AKU is
Autosomal recessive
AKU is a mutation in
Homogentisic oxidase
People with AKU have an inability to metabolize ____ and ___, causing ___ to accumulate
Tyrosine and phenylalanine
Homogentisic acid
Symptoms of AKU
Dark urine
Bark blue or black CT
Arthritis in joints
Destruction of heart valves
Galactosemia is
Autosomal recessive
Galactosemia is due to
GALT mutation
GALT
Galactose-1-phosphate-uridyltransferase
___ and ___ accumulates in galactosemia
Galactose and galactose -1-phosphate
Symptoms of galactosemia
Failure to thrive Neuronal and liver damage Cataracts Vomiting Diarrhea Poor weight gain
Treatment for galactosemia
Discontinue lactose
Restrict lactose in first 2 years
Lysosomal Storage Diseases (LSD) are
Autosomal recessive
LSDs result in excessive storage of metabolites due to
Lack of lysosomal catabolism
PKU most common in
Scandinavian descent
Distinct sign of PKU
Musty or mousy urine odor
Ochronosis
Dark pigments in CT
Features of Lysosomal Storage Diseases
Early onset
CNS damage
Hepatosplenomegaly
Cellular dysfunction, often fatal
Types of LSD
- Tay- Sachs
- Gaucher
- Mucopolysaccharidosis
Types of mucopolysaccaridosis
- Hurler
2. Hunter
Tay-Sachs has mutated ___, resulting in ___ accumulated in brain/spinal cord
Hexosaminidase A enzyme
Gangliosides
____ are 1 in 30 carriers for Tay-Sachs
Ashkenazi Jews
Symptoms of Tay-Sachs
Intellectual disability
Flaccidity
Cherry red central macula
Treatment for Tay-Sachs
NONE
Gaucher Disease has mutated ___, resulting in ____ accumulating
Glucocerebrosidase gene
Glucocerebrosides
Treatment for Gaucher Disease
Lifeline enzyme replacement therapy
Type 1 Gaucher Disease
MC
Less severe
Ashkenazi Jews
Type 2 and 3 Gaucher Disease
More severe
Neuro disturbances
Distinct characteristics of Gaucher Disease
Wrinkled tissue paper cytoplasm
Erlenmeyer flask deformity
Gaucher Disease
Low RBC = ___
Low WBC = ____
Low platelets = ____
Anemia; fatigue
Infections
Bruising
Mucopolysaccharidosis (MPS) deficiency in ___, causing ___ to accumulate
ECM breakdown enzymes
GAGS
Signs of MPS
Intellectual disability Gargoylism Arterial deposits Clouding of cornea Hepatosplenomegaly
Hurler syndrome inheritance
Auto. Recessive
Hurler syndrome deficiency
Alpha -L-iduronidase
Lethal by age 6-10
Hurler syndrome
Hurler syndrome is ____ severe than hunter syndrome
More
Hunter syndrome inheritance
X-linked
Hunter syndrome deficiency
L-iduronate sulfatase
___ and ___ accumulate in both Hurler and Hunter Syndrome
Heparan sulfate
Dermatan sulfate
Glycogen storage diseases are due to suppressed ____, causing ___ to accumulate
Glycogen catabolism
Glycogen
Glycogen storage Disease inheritance
Autosomal recessive
Types of glycogen storage Disease
- Von Gierke Disease
- McArdle Disease
- Pompe disease
Von Gierke Disease causes decreased
Liver glycolysis
Glycogen storage Disease
Von Gierke = ___
McArdle disease = ___
Hepatic
Myopathic
Deficiency in Von Gierke Disease
Glucose 6 phosphatase
McArdle Disease deficiency
Muscle phosphorylase
McArdle Disease can result in
Rhabdomyolysis
Pompe Disease deficiency
Lysosomal acid maltase
Pompe Disease lethal by
Age 2
Rhabdomyolysis
Rapid skeletal muscle destruction
Signs of rhabdomyolysis
Muscle pain Myoglobinuria Confusion Weakness Renal failure
Combined frequency of LSD
1 in 5,000
Type 1 Gaucher Disease aka
Chronic neuronopathic form
Type ___ is more severe than type ___ (Gaucher Disease)
2; 3
Gaucher Disease types 2 and 3 at risk for developing
Parkinson’s disease
Gaucher cells
Glucocerebrosides accumulation in macrophages
People with Von Gierke Disease predisposed for developing
Gout
Xanthomas of skin
Bleeding tendencies
Rhabdomyolysis can be due to
Trauma
Intense physical exercise
MC cause of death in rhabdomyolysis
Renal failure due to myoglobin obstructing glomeruli