Disease Description (Causes and Symptoms)
Alport syndrome is an inherited basement membrane disorder caused primarily by genetic mutations in type IV collagen (particularly COL4A5 and related genes), a major component of basement membranes. It generally affects the glomerular basement membrane (GBM) of the kidneys, the inner ear (cochlea), and the basement membranes of the eyes (cornea, lens, and retina), resulting in the following major symptoms.
- Kidneys: Recurrent hematuria (microscopic or visible) beginning in childhood or adolescence, progressive proteinuria, nephrotic syndrome-like features, and long-term progression to chronic kidney failure (end-stage renal disease, ESRD)
- Hearing: Sensorineural hearing loss (generally developing gradually after adolescence, with some cases progressing to severe hearing loss)
- Eyes: Abnormalities of the cornea, lens, retina, and other structures (changes in transparency and generalized abnormal findings), with possible reduced vision
The inheritance pattern varies, but most cases involve X-linked mutations (COL4A5), with symptoms more severe in males. Autosomal recessive and dominant forms have also been reported. Characteristic pathological findings include thinning, irregular thickening, and a "basket-weave" appearance of the GBM on electron microscopy of kidney biopsy specimens.
Treatment
There is currently no specific gene therapy commercially available that can cure Alport syndrome. Treatment aims to slow disease progression and manage complications.
Key Treatment and Management
- Blood pressure control and reduction of proteinuria: Early administration of an ACE inhibitor (e.g., enalapril, ramipril) or an ARB (e.g., losartan) has evidence supporting delayed progression of proteinuria and decline in the glomerular filtration rate (kidney function). (It may also be considered during the early microproteinuria stage.)
- Renal replacement therapy: Dialysis or kidney transplantation is required when chronic kidney failure (ESRD) progresses. Transplantation improves survival, but anti-glomerular basement membrane (anti-GBM) antibody-related nephritis may rarely occur after transplantation, so monitoring is necessary.
- Hearing and vision management: Monitor progression through regular hearing tests (audiology) and ophthalmologic examinations, and provide hearing aids or cochlear implants when necessary (in cases of severe hearing loss), along with ophthalmologic treatment.
- Genetic counseling: Assess hereditary risk within the family and recommend genetic testing for family members (important for diagnosis, preventive testing, and pregnancy planning).
- Medication and lifestyle management: Follow a low-sodium diet, manage body weight, adjust protein intake (according to the instructions of a physician or dietitian), and avoid nephrotoxic medications (e.g., NSAIDs and aminoglycoside antibiotics).
Precautions
- During pregnancy: ACE inhibitors/ARBs can cause birth defects and harm the fetal kidneys, so women planning pregnancy should consult their treating physician about medication changes and management.
- Acute changes in kidney function may occur during infections or trauma; seek medical attention immediately if symptoms occur.
- Monitoring for complications related to before and after transplantation and medication use (such as hypertension and electrolyte abnormalities) is essential.
Prognosis
- The prognosis varies depending on genotype, sex, and individual differences. Typical X-linked males often progress to ESRD in young adulthood, while female carriers generally have mild to moderate abnormalities and a better prognosis than males. Progression may be delayed through measures such as early use of ACE inhibitors.
Checklist Before an Outpatient Visit (Including Example Questions)
Items/materials to prepare or bring
- A list of current medications (including prescription and nonprescription medications and supplements)
- Previous test results (urinalysis, blood urea nitrogen/creatinine, eGFR, albumin/proteinuria levels) and recent blood pressure records (home measurement logs, if possible)
- Previous kidney biopsy report or genetic test results (if available)
- Family history information (kidney disease, hearing loss, blindness, early glomerular dysfunction, etc.)
- Hearing and vision test results (if available), along with records of when symptoms began and how they have progressed
- Symptom diary: hematuria (when it began, intermittent or persistent), edema, fatigue, changes in urine volume, etc.
Information to report to the doctor during the outpatient visit (examples)
- "My hematuria (or proteinuria) has increased recently. This is when it was first detected, and this is how it has progressed…"
- "Someone in my family has a similar kidney or hearing problem (including the relationship and age)."
- "I am planning a pregnancy (or am pregnant) and would like to discuss the medications I am taking."
Examples of General Questions to Ask the Doctor
- What are the expected effects and side effects of this medication (e.g., an ACE inhibitor/ARB)?
- How can my kidney function (or my child’s prognosis) be predicted based on the current condition?
- When should I begin preparing for more intensive treatment (such as dialysis or transplantation)?
- I am planning a pregnancy; what preparation and medication changes are needed?
- Should genetic testing be recommended for my family? If so, when is the appropriate time?
Examples of Disease-Specific Questions
- What is our family’s genotype (based on test results, if possible), and what is the probability of passing it on to our children? (Including differences according to whether the children are boys or girls)
- Are there any restrictions on an allogeneic (family) donor for transplantation? (For example, the possibility that a family donor may be a carrier)
- I currently have only microproteinuria in my urine; when is it recommended to start an ACE inhibitor?
- How should the kidneys and medications be managed during pregnancy or when planning a pregnancy?
References and Recommendations
- Regular follow-up of kidney function (blood and urine tests), blood pressure, hearing, and vision is important.
- Pursue accurate diagnosis and family management through genetic counseling and, when necessary, molecular genetic testing.
- Medical decisions (such as starting or stopping medication and preparing for transplantation) should be made in consultation with the primary physician and tailored to the individual condition.
(This material summarizes general medical information and cannot be used as a substitute for individual medical care. Please consult the treating specialist for specific diagnosis and treatment.)