**1. Introduction**

Systemic sclerosis (SSc) is a chronic immune-mediated connective tissue disease, including the skin, inner organs, and blood vessels, with heterogeneous multiple organ involvement whose etiology is unknown. It has two subtypes: diffuse and limited. Its incidence ranges from 4 to 43 million people [1–3] per year, with a prevalence of 88–443 million [4, 5]. It can be seen at any age, though it is most commonly seen in patients aged 30–50 years. The disease shows an earlier onset and a more severe course in black patients [6]. The incidence in women is three to four times higher than in men [6]. Epidemiological studies showed that there is a significant increase in SSc risk in people, whose first-degree relatives have this disease [7].
