EXAM 3 Medical Genetics Flashcards
X-linked recessive disorders
- duchess muscular dystrophy
- hemophilia A and B
most common hemophilia
hemophilia A
90%
what is hemophilia A associated with
factor VIII deficiency
symptoms of hemophilia A
tendency toward easy bruising and massive hemorrhage after trauma
Who does hemophilia A occur in
- males
- homozygous females
is hemophilia A common or rare
rare - about 18,000 persons in US have hemophilia; about 400 new cases each year
what kind of penetrance of hemophilia a
variable - variable effect of defective alleles
severe disease of hemophilia a
Factor VIII levels of less than 1-2% normal
what can someone experience with severe disease of hemophilia a
spontaneous bleeding into joints and muscles
moderate disease of hemophilia a
factor VIII levels of 2-5% normal
what can someone experience with moderate disease of hemophilia a
spontaneous bleeding
mild disease of hemophilia a
factor VIII levels of 5-50% normal
what does someone usually experience with mild disease of hemophilia a
bleeding following trauma or surgery
X-linked dominant disorders
- X-linked hypophosphatemia
- focal dermal hypoplasia
- CHILD syndrome
- Rett syndrome
- Fragile X syndrome
- Incontinentia pigmenti
- Lujan–Fryns syndrome
- Orofaciodigital syndrome
who is transmission of maternal inheritance
- affected women transmit to all offspring
- affected men do NOT transmit to offspring
what results in in malfunctions of the respiratory chain for oxidative phosphorylation
mitochondrial inheritance
what kind of inheritance is mitochondrial inheritance
maternal inheritance
what reflects the extent of oxidative phosphorylation in the tissue
phenotypic effects
what organs/systems are most affected by extent of oxidative phosphorylation
- CNS is most sensitive
- followed by skeletal muscle, heart muscle, kidney, liver
mitochondrial inheritance diseases
- Leber’s hereditary optic neuropathy (LHON)
- Myocolonic epilepsy and ragged red fiber disease (MERRF)
- Kearns-Sayre syndrome
loss of vision and cardiac dysrhythmia
Leber’s hereditary optic neuropathy (LHON)
central nervous system abnormalities and deficiencies of skeletal and cardiac muscle function
Myoclonic epilepsy and ragged red fiber disease (MERRF)
neuromuscular symptoms including paralysis of eye muscles, dementia, and seizures
Kearns-Sayre syndrome
complex/multifactoral disorders
chronic diseases
what 2 things are most chronic diseases affected by
both genetic and environmental factors
examples of complex inherited disorders/chronic diseases
diabetes, CVD, asthma, cancer, dyslipidemia
- number of chromosomes in body
2. number of pairs
46
23
___ indicates only one set of chromosomes
haploid
____ indicates two sets of chromosomes
diploid
_____ refers to gain or loss of single chromosomes (ex, 45 or 47 chromosomes in somatic cells
aneuploidy
alternate forms of a gene
allele
where are alleles found?
on homologous chromosomes
what are homologous chromosomes?
chromosomes that carry the same genes (ex 2 copies of chromosome 3)
homologous chromosomes that differ
heterozygous
homologous chromosomes that are the same
homozygous
what is genotype?
the combination of alleles present?
what is phenotype?
the expression pattern of a combined genotype
what is phenotype dependent on?
genotype and environment
sporadic mutations usually result in what type of disease?
autosomal dominant
in autosomal dominant disorders, what percent of children will develop the condition
50%
type of disorders that tend to affect structural proteins
autosomal dominant disorders
how many defective alleles are needed to result in disease in autosomal dominant disorders?
Only one copy of a defective allele is needed
autosomal dominant disorders- nervous system
huntington disease
neurofibromatosis
motonic dystrophy
tubercous sclerosis
autosomal dominant disorders- urinary
polycystic kidney disease
autosomal dominant disorders- GI
familial polyposis coli
autosomal dominant disorders- hematopoietic
hereditary spherocytosis
vin willebrand disease
autosomal dominant disorders- skeletal
marfan syndrome
Ehlers-danlos syndrome
osteogenesis imperfecta
achondroplasia
autosomal dominant disorders- metabolic
familial
hypercholesterolemia
acute intermittent porphyria
Marfan Syndrome % familial
70%-85% familial
Marfan Syndrome % sporatic (new mutations)
15%-30% sporatic (new mutations)
Marfan Syndrome occurs in how many people?
1:5000
Marfan Syndrome has defect in what protein?
fibrillin-1
Marfan Syndrome is Disorder in ________ tissues
connective tissues
where is fibrillin-1 found in body?
Protein product is found in extracellular matrix proteins, especially in aorta, ligaments, ciliary zonules of the lens
fibrillin-1 is Necessary for _____.
elasticity
symptoms of Marfan syndrome
Lax joints, unusually tall, long extremities, including digits, spinal deformities (kyphosis, scoliosis), pectus excavatum, ectopia lentis, MVP, aortic valve incompetence, aorta weakening
High risk of aortic dissection (especially thoracic) occurs in what autosomal dominant disease?
Marfan syndrome
Autosomal Recessive Disorders occurs when (both or one) allele/s code for the disorder
both
Autosomal Recessive Disorders Tend to result from failures in genes that code for _______.
enzymes, receptors, transporters
in Autosomal Recessive Disorders, A person who has inherited the defective gene from only one parent often is _____.
disease-free
