We wish to thank Dr Hasen for pointing out an omission in our article, "Pernicious Anemia, 18q Deletion Syndrome, and IgA Deficiency." The following information lends further support to our original conclusions.
1. Anti-parietal cell antibody was present in our patient's serum. Antimicrosomal antibody (AMA) was also present in a titer of 1:400 (normal, <1:100). Antithyroglobulin antibody (ATA) was negative by radioimmunoassay; however, these results were not available when our- report was drafted. Furthermore, our- patient had normal thyroid function study findings at the ages of 9 months, 10 years, and 14 years. Thus, the sudden onset of hypothyroidism at the age of 21 years associated with a positive AMA titer strongly suggests an "acquired" autoimmune syndrome.
2. In the cases cited by Dr Hasen,1,2 although ATA titers were negative, AMA determinations were not mentioned. Since as many as 25% of patients with autoimmune thyroid disease may have