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Alport Syndrome
Main Features
- Disorder of basement membranes affecting the glomerulus, cochlea, and eye
Eye Findings
- Lens
- Anterior Lenticonus
- bilateral in 75%
- usually absent at birth and appears in 2nd or 3rd decade
- present in 50% of males with X-linked
- may have associated cataract
- Rarely associated with capsular rupture
- Posterior subcapsular cataract associated with diffuse leiomyomatosis
- Fleck Retinopathy- whiteish/yellow flecks in the perimacular region 70% males and 20% females
- associated with retinal failure before age 30 in males
- peripheral retinopathy with temporal retinal thinning on OCT is common
- Cornea
- posterior polymorphous corneal dystrophy and recurrent erosion
- Macular hole- rare
Other Findings
- Renal
- persistent microscopic hematuria, progressing to proteinuria, declining GFR, and ultimately end-stage kidney disease (ESKD)
- kidney biopsy shows basket-weave“ appearance of glomerular basement membrane, thickening and splitting of the lamina densa
- early treatment with renin-angiotensin system blockers can delay progression of end-stage renal disease
- Hearing
- Progressive bilateral high-tone sensorineural hearing loss usually develops by late childhood or early adolescence
Etiology
- X-Linked 80%- COL4A5 mutations
- Autosomal Recessive 15%- biallelic COL4A3 or COL4A4 mutations
- Autosomal Dominant