Genetics Exam 2: Chapter 10 (Collagen Disorders)

What is Osteogenesis Imperfecta (OI)?

genetic collagen disorder resulting in fragile bones

What type of collagen is affected by the mutation in OI?

type 1 collagen

What is the inheritance pattern of OI?

autosomal dominant

What is OI Type 1?

reduced normal amounts of normal collagen

What happens in OI Type 1?

fractures occur due to minor trauma, blue-tinged coloration of sclera

What is OI Type 2?

no normal collagen produced, most severe form

What happens in OI Type 2?

bone fractures and skeletal malformations occur in prenatal period, lethal

What is OI Type 3?

collagen produced is abnormal

What happens in OI Type 3?

fractures present at birth, short stature, muscle weakness, restrictive pulmonary disease

What is OI Type 4?

abnormal collagen is produced but functions better than other types of OI

What happens in OI Type 4?

scleral coloration is normal, less fractures and deformities

How is OI managed?

fracture prevention, physical therapy, braces, movement aids

What is Ehlers-Danlos Syndrome (EDS)?

group of inherited disorders that occur as a result of mutations in the genes responsible for collagen formation or modification

What is the most common inheritance pattern of EDS?

autosomal dominant

What is the mutation in Classical EDS?

mutated type 1 or 5 collagen, autosomal dominant

What is seen in classical EDS?

hyperextensible joints, stretchy skin, chronic joint pain

What is the mutation in hypermobility EDS?

no specific collagen mutation, autosomal dominant

What is seen in hypermobility EDS?

hypermobile joints, chronic joint pain, extensible skin

What is the mutation in Vascular EDS?

mutation of type 3 collagen, autosomal dominant

What is seen in vascular EDS?

thin walls of arteries and intestines, severe disease with early death

What is the mutation in Kyphoscoliosis EDS?

mutation in a gene responsible for modifying collagen, autosomal recessive

What is seen in Kyphoscoliosis EDS?

laxity of all joints, spinal curvature, severe disease with early death

How is EDS managed?

no current cure, manage symptoms, protect joints

What is Marfan Syndrome (MFS)?

connective tissue disorder where there is a mutation in fibrin, preventing its interaction with collagen and elastin

What is the inheritance pattern of MFS?

autosomal dominant

What gene is altered in MFS?

FBN1

What is seen with MFS?

connective tissue is unstable and weak, becomes overstretched

What is the most common cause of premature death in MFS?

cardiovascular complications

What are manifestations of MFS?

tall stature, loose joints, spinal curvature, chest deformities

What complications are commonly seen with MFS?

flat cornea, myopia, widened aorta, aortic aneurysm

How is MFS managed?

yearly cardiology evaluation, maintain controlled blood pressure, healthy weight