Table 2 Phenotypes of known amyloidogenic TTR variants with alleles identified in the Saudi population

c.424G>A(p.Val142Ile) [8, 13, 21,22,23]

• Late-onset cardiomyopathy (over the age of 65), more commonly in men

• Low amyloid load, remaining subclinical in many carriers

c.238A>G(p.Thr80Ala) [8, 15, 16, 24, 25]

• Age of onset in seventh decade of life

• Cardiac amyloidosis and autonomic and peripheral neuropathy

• Gastrointestinal disorders are common. Carpal tunnel syndrome precedes other symptoms in nearly three quarters of patients

c.239C>T(p.Thr80Ile)

[5, 17]

• Qualifies as a dense hot-spot and pathogenic mutation by Varsome, but there are no reports of the clinical manifestation

• It is similar to p.Thr80Ala, as both substitute a native uncharged polar residue with a non-polar residue