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Stickler Syndrome

Stickler Syndrome. COL2A1, COL11A1, COL11A2. Darron Fors & Dr. Robert Seegmiller Brigham Young University. My Pedigree. Me. Symptoms within my family: Cleft palate, hearing loss, osteoarthritis, hypermobile joints (double jointed), myopia. DNA Analysis Report. RESULTS:.

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Stickler Syndrome

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  1. Stickler Syndrome COL2A1, COL11A1, COL11A2 Darron Fors &Dr. Robert Seegmiller Brigham Young University

  2. My Pedigree Me Symptoms within my family: Cleft palate, hearing loss, osteoarthritis, hypermobile joints (double jointed), myopia

  3. DNA Analysis Report RESULTS: DNA sequencing of the COL11A1 gene revealed a c.4537G>A transition in exon 61. This mutation converts a codon for a triple helical domain glycine (GGT) to a serine (AGT). This mutation will result in a phenotype consistent with Stickler syndrome II. The patient is heterozygous for this mutation.

  4. Human Chromosomes • Each cell in human body has 23 pair of chromosomes in the nucleus • Number of genes in our chromosomes is about 30,000 • Genes are segments of DNA, each of which ultimately code for a protein • These proteins and other molecules produced by genes determine the traits of a living organism

  5. Collagen molecules involved in Stickler Syndrome • COL2A1 located on Chromosome 12 • COL11A1 located on Chromosome 1 • COL11A2 located on Chromosome 6

  6. Protein Synthesis • A section (gene) of DNA unwinds and the nucleotides of the DNA provide the pattern for making the messenger RNA (mRNA). • mRNA is used as instructions to piece together amino acids that form proteins • Collagen is one of these proteins

  7. Functions of COL11A1 Gene • The COL11A1 gene provides instructions for making one component of type XI collagen, called the pro-alpha1(XI) chain. Type XI collagen adds structure and strength to the connective tissues that support the body's muscles, joints, organs, and skin. Type XI collagen is normally found in cartilage. Type XI collagen is also part of the clear gel that fills the eyeball (the vitreous), the inner ear, and the center portion of the discs between the vertebrae in the spine (nucleus pulposus). • The pro-alpha1(XI) chain combines with two other collagen chains (pro-alpha2(XI) and pro-alpha1(II)) to form a procollagen molecule. These triple-stranded, ropelike procollagen molecules are then processed by enzymes in the cell. Once processed, procollagen molecules leave the cell and arrange themselves into long, thin fibrils that link to one another (cross-link) in the spaces around cells. The cross-linkages result in the formation of very strong mature type XI collagen fibers. • Type XI collagen also helps maintain the spacing and diameter of type II collagen fibrils. Type II collagen is an important component of the eye and mature cartilage tissue. The size and arrangement of type II collagen fibrils is essential for the normal structure of these tissues. (from the NIH Genetics Reference)

  8. Components of the Extracellular Matrix (ECM)

  9. Importance of types II/XI collagen • Collagen II • Principal fibrillar component of cartilage ECM • Provides cohesive properties of cartilage • Collagen XI • Essential for normal formation of collagen fibrils • Responsible for spatial organization of growth plate • Mutations • In genes encoding polypeptide subunits of collagen II and XI are responsible for several chondrodysplasias

  10. DNA Analysis Report RESULTS: DNA sequencing of the COL11A1 gene revealed a c.4537G>A transition in exon 61. This mutation converts a codon for a triple helical domain glycine (GGT) to a serine (AGT). This mutation will result in a phenotype consistent with Stickler syndrome II. The patient is heterozygous for this mutation.

  11. COL2A1 Mutations 1 2 3 4 5 1 7 6 8 1. Stickler with cleft palate 2. Osteoarthritis with mild chondrodysplasia 3. Lethal chondrodysplasia (hypochondrogenesis) 4. Stickler with severe ophthalmopathy 5. Lethal chondrodysplasia (achondrogenesis II) 6. Severe chondrodysplasia (SED) 7. Severe chondrodysplasia (SED) 8. Severe chondrodysplasia (SED congenita)

  12. What is being done in the lab? • It starts with establishing mouse models for study • Mouse models at Brigham Young University: • Disproportionate micromelia(Dmm) • Micromelia– (dwarfism) • COL2A1 mutation • chondrodysplasia(cho) • Chondro- (cartilage), dysplasia- (abnormality) • COL11A1 mutation • spondlyoepiphysealdysplasiacongenita(sedc) • Spondylo- (bones of the spine), epiphyses- (ends of long bones), dysplasia- (abnormality), congenita- (from birth) • COL2A1 mutation

  13. Dmm and cho have a similar phenotype • Endochondral bone defect —> Dwarfism • Micrognathia —>Tongue obstruction —>Cleft Palate • Small thoracic space —> Pulmonary hypoplasia

  14. My Personal Work Normal (Wild) Type Sedc Heterozygote

  15. What’s the point? • Finding anomalies between the wild type and mutant types • Points us in the right direction to address the problem • Identification of the problem at the molecular level paves the way for discovery of drug treatments • Understanding the roles of specific genes and their interaction with other genes • Essential for possible gene therapy used in the future

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