Transthyretin Cardiac Amyloidosis in the African-American Population

Approximately 4% of African Americans carry the Val122Ile variant for transthyretin (TTR) amyloidosis. This can increase the risk for developing hereditary TTR cardiac amyloidosis (ATTRv-CA). Age-related ATTRwt (wild-type) is the most common cause of ATTR-CA and is seen most often in white males. Here, John Gabrovsek, DDS, retiree and independent research professional, Cleveland Clinic, OH, and colleagues present the racial distribution of ATTR-CA, focusing on the prevalence of ATTRwt-CA in African-American patients compared with ATTRv-CA due to having Val122Ile-positive disease.

This is a retrospective review of patients with ATTR-CA seen between 2008 and 2018 at the Cleveland Clinic. Diagnosis of ATTR-CA “was established via endomyocardial biopsy or with advanced cardiac imaging with appropriate lab testing to rule out light-chain amyloidosis. TTR genetic sequencing was obtained when possible.”

Of 382 patients with ATTR-CA, 118 (31%) identified racially as African American. In the African-American patients with access to genetic testing (N = 104), 75% of cases were due to Val122Ile ATTRv and 23% were due to ATTRwt. There was also 1 case each of variants Asp18Asn and Glu54Gln. The clinical, imaging, and laboratory parameters between African-American patients with Val122Ile ATTRv versus ATTRwt were “overall similar, although the number of patients in the ATTRwt group was too small to make a valid comparison.”

Although the majority of African-American patients with ATTR-CA had ATTRv due to the Val122Ile mutation, nearly one-quarter had ATTRwt. “Current estimates of the prevalence of ATTR-CA in the African-American population focus on those with the Val122Ile variant at risk, but do not account for African Americans who may develop ATTRwt, potentially underestimating the true prevalence,” stated Dr Gabrovsek and colleagues.

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