MCB 164 Project: Alport Syndrome

Ryan HamstengelIan Bateman

Symptoms

Prognosis

Genetic Characteristics

Mechanism of Action

Mechanism of Action

Experiment● Model Organism: Mus Musculus● Hypothesis: If mutated COL4A5 genes do cause Alport

syndrome, then knocking out functional COL45 genes in mice should give the same phenotype as AS positive individuals.

● Methods: Create a retroviral vector expressing a CRISPR guide RNA sequence specific to mice COL4A5 gene. Also include a CAS-9 endonuclease sequence and selectable markers; antibiotic resistance, dominant gene for black fur color.

● Inject retroviral vector into mouse ES cells and select based on antibiotic resistance. Transformed cells are then injected into a pregnant brown mouse’s blastula.

● Chimeric progeny will have black and brown fur color phenotype. Chimeric mice are then bred to produce a true homozygote in females and a hemizygous male line for mt col45.

● Assay for AS phenotype.● Conclusions: If homozygous F2 transmice have same

phenotype as AS positive individuals, then COL4A5 gene’s are necessary for AS.

Existing Treatments● The use of angiotensin blockade may diminish the rate of glomerulosclerosis and disease progression in

patients with Alport syndrome. They may reduce protein excretion and stabilize renal function. Angiotensin blockade with an ACE inhibitor or ARB is a reasonable intervention in any hypertensive patient and should be considered in normotensive patients with evidence of progressive disease or proteinuria. In case of nephrotic syndrome different protocols of immunosuppressants are used.

● Renal failure due to AS is treated by dialysis or, for some, renal transplantation in cases of terminal uremia..

● Gene therapy may one day be able to provide a cure for AS by replacing the faulty COL4A5 gene.

ReferencesKnebelmann, B., Breillat, C., Forestier, L., Arrondel, C., Jacassier, D., Giatras, I., Drouot, L, Deschenes, G., Grunfeld, J.-P.,

Broyer, M., Gubler, M.-C., Antignac, C. “Spectrum of mutations in the COL4A5 collagen gene in X-linked Alport

syndrome.” Am. J. Hum. Genet. 59: 1221-1232, 1996.

LeBleu, V., Sugimoto, H., Mundel, T., Gerami-Naini, B., Finan, E., Miller, C., Gattone II, V., Lu, L., Shield III, C., Folkman, J.,

and Kalluri, R. “Stem Cell Therapies Benefit Alport Syndrome.” J Am Soc Nephrol. 2009 November; 20(11): 2359-2370.

Chiricosta, A., Jindal, S., Metuzals, J., and Koch, B. “Hereditary Nephropathy with Hematuria (Alport's Syndrome).” Can Med

Assoc J. 1970 February 28; 102(4): 396–401.

Kashtan, C., Ding, J., Gregory, M., Gross, O., Heidet, L., Knebelmann, B., Rheault, M., and Licht, C. “Clinical practice

recommendations for the treatment of Alport syndrome: a statement of the Alport Syndrome Research Collaborative.”

Pediatr Nephrol. 2013 January; 28(1): 5–11.

Antón-Martín, P., López, C., Ramiro-León, S., Santillán Garzón, S., Santos-Simarro, F., and Gil-Fournier, B. “Alport Syndrome:

De Novo Mutation in the COL4A5 Gene Converting Glycine 1205 to Valine.” Clin Med Insights Pediatr. 2012; 6: 41–49.