Genetic Disorders (Exam 2) Flashcards
What is a genotype?
Entire genetic composition
What is a phenotype?
Expression of genes
What is a chromosome?
Contains DNA
How many pairs of chromosomes does someone have?
23 pairs of chromosomes (46 chromosomes)
What is a chromosomal Karyotype?
Chromosomal map from a single cell
What is monosomy?
When one chromosome of a pair is missing
What is trisomy?
presence of an extra chromosome
What is deletion?
Part of chromosome is missing; part of genetic code has been omitted
What is translocation?
Part of chromosome has detached & reattached itself to another chromosome
What is the pathophysiology of Trisomy 21 - Down syndrome?
47XX + 21 or 47XY+21
In regards to Trisomy 21 what is non- disjunction?
- 2 chromosomes don’t separate during mitosis so end up with a 3rd chromosome on karyotype 21
In regards to Trisomy 21 what is translocation?
Chromosome stuck to other instead of going to where it should be
In regards to Trisomy 21 what is mosaicism?
- Happens later in development
- Not all cells have trisomy
As the maternal age (BLANK) the incidence of Down Syndrome (BLANK)
As the maternal age increases the incidence of Down Syndrome increases
What is the physical features of Trisomy 21 - Down syndrome?
- Small statue
- Upward slant of eyes
- Wide gap b/w toes 1 &2
- Micrognathia
- Small oral cavity resulting in protruding tongue
- Speckling of iris
- Epicanthal fold of eyes
- Saddle nose
- Small ears
- Short broad hands w/ single palmar crease
What is the neuropathology of Trisomy 21 - Down syndrome?
- Simplicity in convolutional pattern
- Reduced synaptogenesis
- Lack/delay of myelination
- Decreased # of small neurons
- Structural abnormalities of neurons
- Increased # neurofibrillary tangles & senile plaques
What is the clinical picture of Trisomy 21 Down syndrome?
- ID
- Microbrachycephaly
- Cardiopulmonary abnormalities
- Developmental delay
- other medial issues (Seizures, Leukemia, Duodenal atresia/stenosis, senile dementia)
What is the clinical picture of the musculoskeletal for an individual with Trisomy 21 - Down syndrome?
- Hypotonia
- Muscular variations
- Foot deformities
- Hip subluxation/dislocation
- Patellar instability
- Scoliosis
- A/A Instability
What is the clinical picture of the sensory deficits of Trisomy 21- Down syndrome?
- Hearing loss
- Strabismus (estropia)
- Cataracts
- Chronic otitis media
- Nystagmus
- Myopia
How is the Trisomy 21 diagnosed in pre/post natal?
- Aminocentesis
- AFP (Alpha Feto Protein)
- Observation at birth
What is the medial/ surgical treatment for Down Syndrome?
- No treatment
- Lots of medical support for compromised systems
What is the pathophysiology and incidence of Turner Syndrome?
- Patho: 45XO
- Incidence: Female only & no correlation to advanced maternal age
What are some physical features of Turner’s syndrome?
- Webbed neck
- Cubital valgus
- Dorsal edema of hands & feet
- Hypertelorism (wide set of eyes)
- Epicanthal folds
- Ptosis
- Elongated ears
- Growth retardation
What are some other system issues when a patient has Turner Syndrome?
- Congential heart disease
- Kidney malfunctions
- Hearing loss
- Decreased gustatory & olfactory
- Deficits in spatial perception & orientation
- Average intellect in most
- Sexual infantilism
What are some skeletal abnormalities of turner syndrome?
- Hip dislocation
- Foot deformities
- Osteoporosis
- Idiopathic scoliosis
What is the pathophysiology of the fragile X syndrome?
Structural abnormality of X chromosomes
What is the clinical features of a patient with fragile X syndrome?
- Large head/ears/jaw
- myopic
- V shaped palate
- Large testes
- Active/autistic
What is partial deletion of chromosome? And how is it named?
- Section of a chromosome is missing
- Often been deleted in replication process during meiosis
- Named by chromosome # & location of deletion on short or long arm (Q is long arm & P is short arm)
What are the early features of Prader Willi Syndrome?
- Hypotonia
- Expresionless
- Weak cry
- Poor feeding
- slow weight gain
- dysmorphic fascial features
What are some late features of Prader Willi Syndrome?
- Improved muscle tone with coordination & motor delays
- Persistent/compulsive appetite
- Obesity
- Hypogonadism
- Mild/mod ID
- Maladaptive behaviors
What are autosomal dominant disorders a result of?
- Abnormality or mutation in a single gene
- Abnormal or mutated gene overrides the normal allele inherited from the other parent
What is the clinical pictures of osteogenesis imperfecta?
- Types I-IV
- Brittle bones
- Hyper extensible ligaments
- Blue teeth
- Skeletal deformities
- Deafness
- Small stature
- Small limbs
What is the management of osteogenesis imperfecta?
Supportive
What is the clinical picture of tuberous sclerosis?
- Seizures
- Intellectual disabilites
- Sebaceous adenomas
What is the management of Tuberous Sclerosis?
Removal of tubers to stop seizures
What is the clinical picture of Neurofibromatosis/ von Recklinghausen Disease?
- Café au lait spots
- Neurofibroma
- ID
- Seizures
What is the clinical picture of Huntington’s Chorea?
- Movement, thinking & psychiatric disorders
- Decline in physical, mental & behavioral function
- Heart disease
What movement disorders are involved in a patient with Huntington’s Chorea?
- Involuntary jerking or writhing movements
- Muscle problems (rigidity or muscle contractions)
- Slow eye movements, saccades
- Impaired gait, posture & balance
- Difficulty with speech and/or swallowing
How is Huntington’s Chorea managed?
- Just addressing the symptoms
- Unable to prevent the physical, cognitive & behavior declines
Describe Autosomal Recessive disorder
- Allele inherited from each parent is abnormal
- Combo of 2 alleles results in disease state
- Parents do not typically have the specific type of disease
What is the clinical picture of Phenylketonuria?
Untreated causes:
- mental/growth retardation
- seizures
- Movement disorders
How is Phenylketonuria managed?
Diet
- Good prognosis too
What is the clinical picture of Sickle Cell Anemia?
- Related to anemia & thrombosis/infarction
- Severe anemia
- jaundice
- arthralgia
- aseptic necrosis of femoral head
- hemiplegia
- Cranial nerve palsies
- Pulmonary & renal dysfunction
How is sickle cell anemia managed?
Blood transfusion
What is the clinical picture of Cystic Fibrosis?
- Affects digestive & respiratory systems
How is cystic fibrosis managed?
- Replace enzyme in GI
- Clear out secretion
What is the clinical picture of Fredreich’s Ataxia?
- Ataxic gait
- Demetria of UE/LE
- speech distrubances
- Pes cavus
- Cardiomyopathies
How is Fredreich Ataxia managed?
Assistive device
What is the clinical picture of Krabbe’s Disease?
May appear normal at birth, progressive retardation, paralysis, blindness, deafness, pseudo bulbar palsy
- Fatal generally within 2 years
How is Krabbe’s Disease managed?
- Supportive care
What is the clinical picture of Tay Sachs?
- Seen at 6 months
- Loss motor
- Death usually by 5 years old
Describe X-linked recessive inheritance
- Also called sex linked inheritance
- Only affects males
- Females are carriers
- Family history (normal females & affected males)
What is the clinical picture of hemophilias?
- Hemarthrosis
- Hematoma
- Hematuria
- Hemorrhages from minor injuries
How is hemophilias managed?
- Transfusion
- Use of blood clotting factors
How is Muscular Dystrophy- Dushenne’s diagnosed?
- Increased level of creatine kinase
- Muscle biopsy
What is the clinical picture of muscular dystrophy dushenne?
- Worsening musculoskeltal
- Trandelenburg
- Scoliosis
- muscle wasting
How is spinal muscular atrophy diagnosed?
- Serum enzymes
- EMG
- Muscle biopsy
What types of spinal muscular atrophy have a decreased life expectancy?
- Type I & II
What is a “normal” Karyotype?
46, XX
or
46,XY
True or False: Turner Syndrome is only seen in females
True
What is the pathophysiology of Prader Willi Syndrome?
46XY-15q
or
46XX-15q
What is the pathophysiology of Osteogenesis Imperfecta?
Deficit in collagen synthesis
What is the pathophysiology of Tuberous Sclerosis?
Spontaneous mutation related to increased paternal age
What is the pathophysiology of Neurofibromatosis/ von Recklinghausen Disease?
Spontaneous mutation or family related
What is the pathophysiology of Huntington’s Chorea?
Progressive breakdown of nerve cells & gross atrophy of corpus striatum, neuronal degeneration in caudate nucleus/ putamen/deep nuclei & frontal cortex
What is Charcot-Marie- Tooth Disease?
Hereditary motor & sensory neuropathy or perineal muscular atrophy
What is the pathophysiology of phenylketonuria?
Absence of phenylalanine hydroxylase prevents conversion of phenylalanine to tyrosine
What is the pathophysiology of sickle cell anemia?
Chronic hemolytic anemia, sickle shaped RBCs, inheritance of HbS
What is the pathophysiology of Cystic Fibrosis?
Effects exocrine glands & sweat glands
What is the pathophysiology of Fredreich’s Ataxia?
Degeneration of posterior spinal roots, posterior spinal cord, cerebellum, dorsal & ventral degeneration of spinocerebellar tracts & lateral corticospinal tracts
What is the pathophysiology of Tay Sachs Disease?
- genetic mutation on chromosome 15q
- inability to produce hexosaminidase
- CNS degeneration
What is the pathophysiology of hemophilias?
Bleeding disorders due to inherited deficiencies or abnormalities of coagulation factors
What is the pathophysiology of Muscular Dystrophy - Duchenne’s?
- Dysfunctional dystrophin gene, dystrophin protein not functioning properly
- Muscles can compensate for a while but over time the abnormal dystrophin leads to damage to muscle cells.. leads to infiltration of connective tissue/fat into the muscle
What is pseudo hypertrophy?
Presentation of large gastrocnemius due to infiltration of fat & connective tissue
What is the pathophysiology of spinal muscular atrophy?
-Disease of anterior horn cells
- Accelerated rate of neuronal cell apoptosis
