The genetics of allergic contact hypersensitivity to nickel

We have examined evidence for familial disposition to nickel allergic conta ct dermatitis (Ni ACD). 258 patients attending for routine patch testing we n recruited prospectively. 39 patients were diagnosed with Ni ACD. 31 of 20 9 1st-degree relatives (15%) of probands had a history of nickel hypersensi tivity. 84 patients with no history of nickel hypersensitivity and negative patch tests to nickel were used as controls. 24 of 458 1st degree relative s of controls (5.2%) had a history of Ni ACD. The risk ratio for 1st degree relatives of a patient with Ni ACD is 2.83 (95% confidence intervals are 2 .45, 3.27). This is the 1st study to present a statistic to represent risk to relatives of developing ACD. Relatives of patients with Ni ACD have an i ncreased risk of developing the condition, but the genetic basis for this i s not yet known. With currently available techniques, this value of relativ e risk makes a positional cloning approach to gene identification impractic al.