The median age at diagnosis with CLL is around 70 years, although 11% of patients being diagnosed are under the age of 55 years (Oscier et al., 2012). CLL incidence strongly correlates with age, rising sharply in the 45–49 age group (CRUK, 2014) and is around 18 per 100,000 in those aged 65–70 years (Gibson et al., 2013). Highest rates are seen in patients aged more than 85 years (CRUK, 2014).

CLL is more prevalent in males than females with a male: female ratio of approximately 2.5:1 in the 45–49 years age group (CRUK, 2014; Ruchlemer et al.,2015).

CLL incidence is higher in Caucasians compared to other racial groups (Ruchlemer et al., 2015). However, although rarer in Asians, a UK report identified that patients of South-Asian origin tend to have more aggressive CLL compared to the Caucasian population (Jain & Rai, 2012).

Epidemiological surveys have shown a 7- to 8.5-fold increase in the relative risk of CLL in first-degree relatives of patients with CLL. Furthermore, a 2.5-fold risk is seen for other lymphoid malignancies, such as lymphoplasmacytoid lymphoma and hairy cell leukaemia, in the relatives of patients with CLL (Gibson et al., 2013; Ruchlemer et al., 2015).