[Is familial screening useful in selective immunoglobulin A deficiency?]

Selective immunoglobulin A deficiency (SIgAD), the most common primary immunodeficiency, is often asymptomatic. High rates of familial clustering have been described in SIgAD, but the causative genetic defect and mechanism of inheritance are unknown.

To determine whether familial SIgAD cases show more severe clinical and immunological characteristics than sporadic ones; to investigate the utility of screening first-degree relatives (FDRs) of these patients, and to determine whether symptoms in affected family members are important enough to justify screening.

Descriptive, cross-sectional study (October 2010-September 2011) of all patients with SIgAD and followed up in our center. Demographic, clinical, and analytical data were reviewed. A familial case was defined as an SIgAD patient with at least one affected FDR.

Of the 130 participants, 42 were SIgAD patients and 88 FDR. There were 13 (31%) familial cases and and 14 (16%) affected FDRs. Six family members had to be analyzed in order to detect one affected one. There were no clinical differences between familial and sporadic SIgAD cases. The percentages of intestinal disease (p=001, OR=9.57, 95%CI 2.59-35.3), hospitalizations (p=045, OR=4.01; 95%CI 1.10-14.67], and need for chronic treatment (p=006, OR=5.5; 95%CI 1.57-19.54) were higher in affected FDRs than in unaffected ones.

The symptoms were not more severe in familial than sporadic SIgAD cases. Nonetheless, the elevated prevalence of affected FDRs with significant morbidity may justify routine screening of close family members of these patients.