Vogt–Koyanagi–Harada syndrome in Greenland

Editor, I n a recent issue of Acta Ophthalmologica, Ostergaard et al. reported the first published case of Vogt– Koyanagi–Harada syndrome (VKH) in a Greenlandic Inuit (Ostergaard et al. 2008). They stated that the prevalence of the disease in this population may be low, although it is not formally known. Following their initial description, we diagnosed two additional acute VKH cases in unrelated Greenlandic Inuits. Two female patients (39 and 40 years old, respectively) of Inuit descent were referred to our institutions for evaluation of bilateral granulomatous panuveitis with bilateral papilloedema, serous retinal detachments, headache and tinnitus. Ultrasonography showed diffuse choroidal thickening, and fluorescein angiography findings were typical of acute VKH in both patients. Integumentary manifestations were not present. An extensive work-up ruled out infectious and other inflammatory causes of uveitis and acute uveomeningitis. Neither of the patients had histories of ocular trauma. In the absence of integumentary manifestations, incomplete VKH was diagnosed in both patients based on the revised disease diagnostic criteria (Read et al. 2001). Both patients responded well to topical and systemic prednisolone therapy (1 mg ⁄kg ⁄day), slowly tapered over 6–12 months without recurrence. Human leucocyte antigen (HLA) genotyping was performed in one patient, who was HLA-DR4 positive. Based on those two patients and on the previous report by Ostergaard et al. (2007), VKH might be a more common disease in Greenlandic Inuits than previously thought. Indeed, a retrospective evaluation of newly diagnosed cases of VKH in Greenlandic Inuits revealed one new case per year for the last 3 years (2005–2007). Considering that the Greenlandic Inuit population in 2007 was 50 366 (Statistics Greenland; http://www. statgreen.gl), the estimated yearly incidence of the disease is approximately 1 ⁄50 000, or 20 cases per million, which is even more than the incidence in a Japanese population (Murakami et al. 1994). This estimate seems accurate for the aforementioned period because ophthalmological care in Greenland is centralized and provided by a Danish company of ophthalmologists (Ojenlaegerne i Gronland; http:// www.oejenlaegerneshus.dk) who refer all posterior uveitis patients from Greenland to one of our own two institutions for evaluation and treatment. We are aware that this retrospective evaluation is exposed to bias, including local underdiagnosing of uveitis as well as a coincidental accumulation of new cases of VKH over a short period of time, leading to either falsely low or falsely high incidence estimates. However, with three incident cases in 3 years it is statistically unlikely that the disease incidence of VKH is less than six per million per year, which is comparable to previous Japanese figures (6.5 per million per year) (Murakami et al. 1994). Further prospective evaluation is needed in order to obtain an accurate evaluation of the disease incidence and prevalence in Greenland. The prevalence of VKH varies among different populations of the world, and is rare in White individuals. VKH affects primarily more pigmented population groups, such as Hispanics, Asians, Native Americans, those from the Middle East and Asian Indians, suggesting a genetically determined susceptibility to a triggering event of the disease (Read et al. 2001). The HLA genotypes of the examined Inuit cases are in accordance with findings in other VKH patients (Ostergaard et al. 2007), and we believe that Greenlandic Inuits may be considered among the racial groups presenting VKH. Incomplete presentation of the disease is a possible explanation of previously underdiagnosed cases. References