Diagnostic evaluation of individuals suspected of Alport syndrome include:
- Medical history and physical examination, including urinalysis and blood testing
- Detailed family history and possibly urinalyses on first- and second-degree relatives
- Hearing and vision evaluation and testing
- Renal ultrasound
- Genetic testing (through blood or saliva). Note: As of January 1, 2021, no charge or minimum charge genetic testing and counseling options are available for eligible individuals via KIDNEYCODE and Renasight. Please visit their respective websites for eligibility criteria and further details.
Urine sample analysis can uncover hematuria and/or proteinuria. Hematuria is present in 100% of males with X-linked Alport syndrome, 95% of females with X-linked Alport syndrome, 100% of males and females with autosomal recessive Alport syndrome, and most individuals with autosomal dominant Alport syndrome.
Alport syndrome produces unique changes in the walls of the blood vessels of the glomeruli that can be detected by performing electron microscopy on the kidney biopsy material. Kidney biopsies can also be tested for the presence or absence of the type IV collagen alpha-3, alpha-4 and alpha-5 chains (the protein products of the COL4A3, COL4A4, and COL4A5 genes). This information is helpful in confirming a suspected diagnosis of Alport syndrome and can often determine the genetic form of the disease.
Skin biopsy may be diagnostic when X-linked Alport syndrome is suspected. The type IV collagen alpha-5 chain is normally present in the epidermal basement membrane and a biopsy of the skin can be tested for the presence or absence of this collagen chain. Approximatey 80% of male patients and 60% of female patients with X-link Alport syndrome will show abnormal staining for the alpha-5(IV) chain in the skin. This approach is especially useful if kidney biopsy poses excessive risk, such as in patients with kidney failure and genetic testing is not feasible. Note: Because the alpha-3 and alpha-4 chains of type IV collagen are not present in the skin, this test cannot be used to diagnose autosomal forms of Alport syndrome.
Alport Syndrome & Women: New Research & Changed Thinking
According to Dr. Clifford Kashtan, one of the leading experts on Alport syndrome, “It is just as important to diagnose Alport syndrome in girls as in boys,” as early and accurate diagnosis is crucial for early intervention.
Alport families are aware that affected boys will someday develop kidney failure, but they often believe that affected girls have no risk of end stage renal disease. Women with Alport syndrome may think that they are only carriers of a mutation and have no need for regular monitoring. Over 95% of women with X-linked Alport syndrome have blood in the urine, so they have the disease. Furthermore about 75% of affected women develop persistent proteinuria at some time during their lives. Although the risk of kidney failure is much lower in females compared to men, there is a significant risk. About 20-30% of women with the X-linked form of Alport syndrome reach end-stage kidney disease by the age of 60. Females with Alport syndrome can also develop hearing loss.
Confirmation of a suspected Alport syndrome diagnosis has changed as new research comes to light. According to the National Organization for Rare Diseases, “When clinical information and family history strongly suggest a diagnosis of Alport syndrome, genetic testing, using the techniques of next generation or whole exome sequencing, can confirm the diagnosis, establish the inheritance pattern and provide useful prognostic information.”