Amyloidosis

Gene: APOA4

Green List (high evidence)

5 families with autosomal dominant medullary amyloidosis. WGS/WES identified 2 different variants in the APOA4 gene (p.D33N in 3 families and p.L66V in 2 families). The variants were absent in gnomAD, located at the structurally flexible N-terminal domain of APOA4, and segregated with disease. There were 48 genotype +ve individuals with 44/48 having an eGFR <60. All clinically affected individuals presented with a bland urinary sediment, CKD, and no clinical evidence of systemic amyloidosis. Mean age of dialysis/transplantation was 58+/-11yrs. Routine kidney biopsies limited to the kidney cortex showed tubulointerstitial fibrosis and secondary glomerulosclerosis and no amyloid deposition. Four affected individuals were shown to have isolated medullary deposition of amyloid, with mass spectrometry showing the mutated Apoa4 as the primary constituent in 3 available cases.
Plasma total ApoA4 levels were increased for patients (n=15) with ApoA4 mutations versus controls (n=49). They hypothesize that the amino acid substitutions alter the tertiary or quaternary structure of the mutated ApoA4, leading to increased plasma and primary urine concentrations and isolated medullary amyloid deposition.
Sources: Literature

Created: 10 Nov 2024, 10:12 p.m.

Mode of inheritance
MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted

Phenotypes
Autosomal dominant renal medullary amyloidosis

Publications

• PMID: 38096951