However, it is worthy of mention that thyroid dysfunction, AITD, and anti-TPO positivity prevalence varies among RA patients based on geographical locations as instance prevalence of AITD among RA patients can range from 0.5% in Morocco [18] to 27% in Slovakia [19]; and anti-TPO differ from 5% [20] in Egypt to 37% in Italy [21]. This evidence concerns the gene TPO and rheumatoid arthritis.