Two novel APOA1 gene mutations in a Japanese renal transplant recipient with recurrent apolipoprotein A-I related amyloidosis.

Apolipoprotein A-I amyloidosis is a rare, autosomal dominant disorder of APOA-1 gene characterized by the deposition of apolipoprotein A-I in various organs and can be classified into either hereditary or nonhereditary form in the absence of a family history. Renal disease caused by Apolipoprotein A-I amyloidosis commonly manifested as slowly progressive renal function impairment without heavy proteinuria. Apolipoprotein A-I-related amyloidosis of kidney is of pathogenetic interest because the renal failure is due to peritubular and interstitial amyloid deposits without glomerular deposits. Tubulointerstitial lesion of amyloid deposits was diagnosed in half of carriers of APOA1 gene mutation, only 13% of patients progressed to renal failure requiring hemodialysis or kidney transplantation. Recurrence of apolipoprotein A-I-related amyloidosis after kidney transplantation is very rare. We report a case of a 63-year-old Japanese female without a family history of kidney and/or liver disease who showed slowly progressive renal graft dysfunction without overt proteinuria. Graft biopsy revealed characteristic Congo red stain positive amyloid deposits localized in the renal interstitial area. No glomerular, vascular and tubular amyloid deposits were noted. Laser microdissection-liquid chromatography tandem mass spectrometry-based proteomic analysis elucidated the type of amyloidosis as apolipoprotein A-I amyloidosis. Genetic analysis of DNA sequence study revealed two novel APOA1 gene mutations of Leu202Arg and Lys262Asn. This is a first and very rare case report of the recurrence of non-familial hereditary apolipoprotein A-I amyloidosis in Japanese transplant recipient.