Genetic Bone Disorders Flashcards
What is DNA composed of?
Nitrogen
Phosphorous
Sugar
What are the 2 categories of bases?
Purines
Pyramidines
What are the nuleotide bases in DNA?
Adenine
Guanine
Cytosine
Thymine
What is a genome?
Pair of matched chromosomes
General inheritance pattern of a METABOLIC condition?
Recessive
General inheritance pattern of a STRUCTURAL CONDITION?
Dominant
What is aneuploidy?
Loss or gain of entire chromosome
Name the 4 cell cycles
G1 - Initial growth
S - DNA replication/synthesis
G2 - Gap
M - Mitosis
What type of inheritance pattern seen in single gene aberrations?
Mendelilan Inheritance
Autosomal dominant - how many children affected?
50% 2/4
Autosomal recessive - how many children affected>
25% 1/4
What is the ONLY X linked Dominant Ortho condition?
Hypophasphataemic Rickets
Name 3 X linked recessive Ortho conditions? XLR
- Duchenne’s
- Hemophilia
- SED Tarda
DHS
Name 4 autosomal dominant (AD) conditions?
- Achondroplasia
- OI
- NF
- Marfan Syndrome
MOAN
What mutation is responsible for achondroplasia?
FGF receptor 3
Most common orthopedic issues with Achondroplasia?
Spinal stenosis - lumbar and foramen magnum
What it the pathophysiology behind Osteogenesis Imperfecta?
Defect in Type 1 collagen
COL1A1 COL1A2 genes - code for alpha chains 1 and 2 of collagen
Severity depends on amount of mutations and % of abnormal chains
What is the main path in NF 1
Defect in Neurofibromin = tu supressor gene
What are Mucopolysaccharidoses?
Group of 13 metabolic syndromes
Caused by malfunctioning/ absence of lysosomal enzymes - which breakdown GAG
What are the manifestations of Mucopolysaccharidoses?
Dwarfism
Atlanto-occiptal instability
What is the pathophysiology behind Duchennes?
Absence of dystrophin protein
Progressive replacement of muscle with fibrous/fatty tissue
Orthopedic manifestations of Duchennes?
Calf pseudohypertrophy
Scoliosis
Equinovarus foot deformity
Joint contractures
Difference between Duchenne’s and Beckers?
Beckers = decreased dystrophin protein instead of absent
Hemophilia types and coagulation factor involved?
A - 8
B - 9
What is Ehlers-Danlos syndrome?
Connective tissue disorder
Type V collagen
What is Marfan Syndrome?
Connective tissue disorder
Fibrillin defect
Ortho manifestations of NF
Scoliosis
Rib humps
What is the classification system for OI + most common type?
Sillence
Type 1
