an oral parafunctional habit may be a contributory factor. Persons with parafunctional habits related to the tongue may show scalloping on the sides of the tongue (crenated tongue). Some suggest that hormonal factors may be involved, because one reported case in a female appeared to vary in severity in correlation with oral contraceptive use. People with geographic tongue frequently claim that their condition worsens during periods of psychologic stress. Geographic tongue is inversely associated with smoking and tobacco use. Sometimes geographic tongue is said to run in families, and it is reported to be associated with several different genes, though studies show family association may also be caused by similar diets. Some have reported links with various human leukocyte antigens, such as increased incidence of HLA-DR5, HLA-DRW6 and HLA-Cw6 and decreased incidence in HLA-B51. Vitamin B2 deficiency (ariboflavinosis) can cause several signs in the mouth, possibly including geographic tongue, although other sources state that geographic tongue is not related to nutritional deficiency. Fissured tongue often occurs simultaneously with geographic tongue, and some consider fissured tongue to be an end stage of geographic tongue. In the past, some research suggested that geographic tongue was associated with diabetes, seborrheic dermatitis and atopy, however newer research does not corroborate these findings. Others suggest allergy as a major factor, e.g. to nickel sulphate. Some studies have reported a link between geographic tongue and psoriasis, although 90% of children who are diagnosed with geographic tongue do not develop psoriasis. Again however, modern research studies do not support any link between psoriasis and geographic tongue. Lesions that are histologically indistinguishable from geographic tongue may also be diagnosed in reactive arthritis (arthritis, uveitis/conjunctivitis and urethritis). Predisposing Factors Geographic tongue (GT) is a lesion with an unknown origin. However, it has been reported more frequently in people with psoriasis, history of allergies, asthma and rhinitis. Studies have also suggested that psychological/psychiatric factors, diabetes, gastrointestinal diseases and haematological disorders may predispose to GT however, more studies with a larger cohort are needed to determine if GT could be an oral manifestation of a systemic disease. There is strong evidence to support a high prevalence of celiac disease and iron-deficiency anaemia in patients with GT. Oral candidiasis and caries are commonly reported in patients with GT, however this can be explained by saliva of a lower pH which will promote the cariogenic process. Most common areas in which GT can