Hereditary nephrology · KIMS Secunderabad
Alport Syndrome — Hereditary Nephritis Affecting the Kidneys, Hearing, and Eyes
Alport syndrome is a hereditary disorder of type IV collagen — the structural protein that forms the basement membranes of the kidneys, the inner ear, and the eyes. Mutations in the genes encoding the alpha-3, alpha-4, or alpha-5 chains of type IV collagen (COL4A3, COL4A4, or COL4A5) cause the glomerular basement membrane to be structurally abnormal — too thin, too irregular, and progressively unable to maintain its filtering function. The result is a lifelong kidney disease beginning with haematuria in childhood, progressing through proteinuria and declining eGFR in young adulthood, and reaching end-stage renal disease in the 20s to 40s in most affected males.
Alport syndrome is one of the most important hereditary kidney diseases to diagnose early — not because there is a cure, but because early treatment with ACE inhibitors or ARBs significantly delays the progression to kidney failure, and because accurate genetic diagnosis guides family screening, transplant planning, and genetic counselling. The diagnosis requires kidney biopsy with electron microscopy — EM is the only test that can directly visualise the characteristic thinning, lamellation, and splitting of the glomerular basement membrane that defines Alport syndrome. KIMS performs EM in-house in its NABL-accredited laboratory — a capability that is not available at most centres in Hyderabad.
Genetics — three inheritance patterns
Alport syndrome is inherited in three patterns determined by which collagen chain is affected and whether one or both gene copies carry the mutation. The pattern dictates severity, sex distribution, and the approach to family screening.
X-linked Alport syndrome (XLAS) — COL4A5 — ~80% of all Alport
Inheritance: X-linked. Caused by mutations in COL4A5 on the X chromosome. Males (hemizygous): always severely affected — haematuria from infancy, proteinuria by teens, ESRD typically by 20s to 30s. Females (heterozygous carriers): variable — some have haematuria only (thin GBM disease), others progress to significant proteinuria and CKD. 15% of carrier females reach ESRD by age 60.
Autosomal recessive Alport syndrome (ARAS) — COL4A3 or COL4A4 — ~15% of Alport
Inheritance: autosomal recessive. Both alleles of COL4A3 or COL4A4 are affected. Both sexes equally severely affected — similar to XLAS males in progression. Parents are heterozygous carriers with thin GBM disease (haematuria, mild CKD).
Autosomal dominant Alport syndrome (ADAS) — COL4A3 or COL4A4 — ~5% of Alport
Inheritance: autosomal dominant. One allele of COL4A3 or COL4A4 is affected. Slower progression — ESRD in 50s to 70s. Clinically similar to thin GBM disease in many carriers. Genetic testing essential to distinguish from benign thin GBM disease.
Identifying the inheritance pattern in the index patient determines who in the family should be screened — and the intensity of monitoring required. Genetic testing of the patient and first-degree family members is part of the KIMS Alport syndrome workup.
Clinical features — the triad of kidneys, hearing, and eyes
Kidney — the progressive disease trajectory
Persistent microscopic haematuria from infancy — the earliest and most consistent finding. Red blood cells are dysmorphic (fragmented by the abnormal GBM) on urine microscopy.
Episodic macroscopic haematuria during childhood — following respiratory infections (similar to IgA nephropathy — an important differential diagnosis). Decreasing frequency after adolescence.
Proteinuria develops in the teens — initially mild, progressing to significant proteinuria as the GBM becomes more damaged.
Declining eGFR — typically from the late teens or early 20s in affected males, progressing to ESRD at a rate that varies by genotype, mutation type, and treatment.
Hypertension — develops as kidney function declines.
Sensorineural hearing loss
High-frequency sensorineural hearing loss is present in 80 to 90% of males with XLAS by late adolescence — it does not affect speech initially (speech frequencies are preserved) but is detectable on audiometry. It progresses to involve speech frequencies with age. Hearing loss is also present in females with XLAS and in ARAS patients. The hearing loss is caused by abnormal type IV collagen in the cochlea. Hearing aids are required as the hearing loss progresses. Audiological assessment is part of the KIMS Alport syndrome evaluation.
Ocular abnormalities
Anterior lenticonus — a forward conical protrusion of the anterior lens — is virtually pathognomonic of Alport syndrome, present in 25 to 30% of affected males. It causes progressive myopia and is detected on slit-lamp examination.
Macular flecks — yellowish-white perimacular deposits — in 15 to 20% of patients. Usually do not affect vision significantly.
Corneal lesions — posterior polymorphous corneal dystrophy in a smaller subset.
Diagnosis at KIMS — why EM is essential
Urine microscopy
Dysmorphic red blood cells and red cell casts on phase-contrast microscopy suggest glomerular haematuria. Urine ACR quantifies the degree of proteinuria.
Genetic testing
Next-generation sequencing panel covering COL4A3, COL4A4, and COL4A5 identifies the causative mutation in 80 to 85% of clinically suspected Alport syndrome cases. A positive genetic result confirms the diagnosis without kidney biopsy in index cases. Family members of confirmed cases can be tested by targeted sequencing of the identified mutation.
Kidney biopsy with NABL LM + IF + EM at KIMS
The kidney biopsy is essential when genetic testing is negative or inconclusive, when the diagnosis is uncertain, or when a family member presents with haematuria and the index case has not had genetic testing.
The three biopsy components:
Light microscopy (LM)
Non-specific in early Alport syndrome. May show focal segmental sclerosis in advanced disease. Does not show the characteristic GBM changes.
Immunofluorescence (IF)
Absence of alpha-3, alpha-4, or alpha-5 chain staining on the GBM (using chain-specific antibodies) is highly specific for Alport syndrome. This requires specialised antibodies and is performed in-house at KIMS.
Electron microscopy (EM)
The definitive diagnostic test. EM directly visualises the GBM ultrastructure. In Alport syndrome, EM shows the characteristic GBM changes: thinning in early disease, followed by irregular thickening, splitting into multiple lamellae (the 'basket-weave' or 'lamellated' pattern), and electron-dense inclusions. No other condition produces this specific EM pattern. EM is performed in-house at KIMS's NABL-accredited laboratory — it is not outsourced.
Why EM matters. EM is the only test that can diagnose Alport syndrome when genetic testing is negative or inconclusive, and is essential for accurate diagnosis of thin GBM disease (which may represent a carrier state or early Alport).
Most centres in Hyderabad cannot perform EM in-house — outsourcing introduces delay and quality variation.
At KIMS, EM is performed in the NABL-accredited laboratory with results available within 7 to 10 working days.
Treatment — slowing progression with renin-angiotensin system blockade
There is no cure for Alport syndrome — the underlying collagen gene mutation cannot be corrected with currently available therapies. However, the rate of progression to ESRD can be significantly delayed by early initiation of ACE inhibitors or ARBs:
ACE inhibitors and ARBs — the foundation of treatment
The Alport Syndrome Treatments and Outcomes Registry (ATHENA) study showed that men with XLAS who started ACE inhibitor therapy at the microalbuminuria stage (before overt proteinuria) reached ESRD 10 years later than those who started treatment after overt proteinuria developed. ACE inhibitors reduce proteinuria, lower intraglomerular pressure, and slow GBM deterioration by reducing the mechanical stress on the already fragile basement membrane. Treatment is started at the first sign of proteinuria — ideally at the microalbuminuria stage (ACR 3 to 30 mg/mmol).
Sparsentan — emerging targeted therapy
Sparsentan — a dual endothelin-1 and angiotensin II receptor antagonist — has recently shown significant proteinuria reduction in Alport syndrome clinical trials and is emerging as an additional treatment option.
Blood pressure control and kidney protection
Blood pressure control below 130/80 mmHg is essential alongside RAAS blockade. Strict blood pressure control reduces ongoing glomerular injury and slows the progression of chronic kidney disease in Alport syndrome patients.
Avoidance of nephrotoxic injury
Avoidance of nephrotoxic drugs (NSAIDs, aminoglycosides) and smoking is important in all Alport patients. These factors accelerate kidney damage and may worsen proteinuria and decline in eGFR.
Kidney transplant in Alport syndrome
Alport syndrome patients who reach ESRD are excellent transplant candidates — the disease does not recur in the transplanted kidney (the donor kidney has normal type IV collagen). At KIMS, Alport syndrome patients with ESRD are evaluated for kidney transplant alongside their dialysis management.
An important consideration: approximately 3 to 5% of male Alport syndrome patients develop anti-GBM nephritis in the transplanted kidney — because the normal alpha-3 and alpha-5 chains in the donor GBM are foreign to an individual who has never expressed these proteins, and an anti-GBM antibody response is triggered. This complication is managed with plasma exchange and immunosuppression, similar to primary Goodpasture syndrome.
Book an Alport Syndrome Consultation at KIMS — Genetic Testing and EM Biopsy Available
Frequently Asked Questions — Alport Syndrome
Alport syndrome is inherited in three patterns. X-linked Alport syndrome (80% of cases) is caused by mutations in the COL4A5 gene on the X chromosome — males (who have only one X chromosome) are severely affected; females (who have two X chromosomes) are carriers with variable severity from haematuria-only to CKD. Autosomal recessive Alport syndrome (15% of cases) requires mutations on both copies of COL4A3 or COL4A4 — both parents are carriers with thin GBM disease. Autosomal dominant Alport syndrome (5% of cases) requires a mutation in only one copy of COL4A3 or COL4A4 — slower progression. Genetic testing identifies the inheritance pattern and allows family members to be screened.
Persistent microscopic haematuria from infancy in a male child, particularly with a family history of kidney disease, deafness, or males in the family reaching dialysis at a young age, should prompt evaluation for Alport syndrome. The evaluation at KIMS includes: urine microscopy (dysmorphic red cells), urine ACR, hearing assessment, ophthalmology review, family history mapping, genetic testing (COL4A3, COL4A4, COL4A5 panel), and kidney biopsy with EM if genetic testing is inconclusive. Early diagnosis allows early ACE inhibitor therapy — which significantly delays ESRD.
No — females are affected in X-linked Alport syndrome, but usually less severely than males. Female carriers of COL4A5 mutations (X-linked Alport) have persistent microscopic haematuria, and 15 to 30% develop significant proteinuria and CKD. Approximately 15% of female carriers reach ESRD by age 60. In autosomal recessive Alport syndrome, females are equally severely affected as males. In autosomal dominant Alport syndrome, both sexes are affected but progression is slower. The assumption that Alport syndrome only affects males is incorrect and leads to under-diagnosis and under-treatment of female family members.
There is currently no cure for Alport syndrome — the underlying gene mutation cannot be corrected with available treatments. However, disease progression can be significantly slowed with early ACE inhibitor therapy. The difference in age at ESRD between men treated early (at microalbuminuria stage) and those treated late (at overt proteinuria stage) is approximately 10 years — a decade of functional kidney life preserved by early treatment. Gene therapy for Alport syndrome is in preclinical research stages but is not yet a clinical option.
Thin basement membrane nephropathy (TBMN) — also called thin GBM disease or benign familial haematuria — is a condition in which the GBM is uniformly thin (below 250nm on EM, compared to the normal range of 300 to 400nm) but does not show the irregular thickening, splitting, or lamellation of Alport syndrome. Most TBMN patients have heterozygous mutations in COL4A3 or COL4A4 — meaning they are carriers for autosomal recessive Alport syndrome. Most TBMN patients have a benign long-term course with only haematuria and minimal or no proteinuria. However, a proportion develop significant CKD over decades — particularly those with additional risk factors (hypertension, obesity, other nephrotoxic exposures). The distinction between TBMN and early Alport syndrome requires EM and genetic testing.
Early — at the first sign of proteinuria (ACR above 3 mg/mmol, the microalbuminuria threshold). The ATHENA registry data show the greatest benefit from ACE inhibitors started before overt proteinuria (PCR above 50 mg/mmol). In males with confirmed XLAS where ESRD by the 30s is expected without treatment, some centres start ACE inhibitors even before proteinuria is detectable, based on genetic diagnosis alone. At KIMS, the decision is made by the nephrologist based on the specific gene mutation (which predicts severity), current proteinuria, eGFR trajectory, blood pressure, and family history of progression rate.
Yes — kidney transplant is the treatment for Alport syndrome ESRD and is very successful. The transplanted kidney has normal type IV collagen and does not develop Alport syndrome. KIMS performs kidney transplants in Alport syndrome patients, coordinated between the nephrology and transplant surgery team. Living related donors (parents, siblings, children) from the same family must be carefully evaluated — family members with the same COL4A mutation should not donate, as they have a higher risk of developing CKD themselves. An unrelated living donor or deceased donor is preferred for X-linked and autosomal recessive Alport syndrome.
KIMS Secunderabad — Dr. Aswini Dutt T (glomerular disease subspecialty), NABL-accredited kidney biopsy with electron microscopy performed in-house (not outsourced — the essential test for GBM ultrastructure assessment), COL4A type IV collagen chain-specific immunofluorescence, genetic testing coordination, early ACE inhibitor protocol, audiological and ophthalmological referral, transplant programme with living donor evaluation that excludes affected family members. Call 040-4488-5000.