Thyroid function and morphology in subjects with microdeletion of chromosome 22q11 (del(22)(q11)).

INTRODUCTION: Monoallelic microdeletion of chromosome 22q11 (22q11DS) is considered to be the commonest human microdeletion syndrome. Abnormalities of thyroid function are sporadically reported in this syndrome, but very few studies have specifically assessed this issue, and thyroid morphology has not been systematically studied. DESIGN: To evaluate the prevalence of abnormalities of thyroid function and morphology in a cohort of paediatric and adult patients with 22q11DS. METHODS: Thirty patients with 22q11DS (median age 9.7, range 1.5-43.9 years) were studied. In all subjects, serum free-T(3), free-T(4), TSH, thyroperoxidase, thyroglobulin, and TSHr auto-antibodies, as well as thyroid ultrasonographic data, were evaluated and compared with age- and sex-matched healthy control groups, for paediatric and adult patients. RESULTS: Fourteen (46.6%) patients showed thyroid hypoplasia involving the entire gland. In all the patients, the volume of the left lobe of the thyroid was significantly reduced (P < 0.01). Among the subjects with thyroid hypoplasia, 10 out of 14 (71%) showed a concomitant heart malformation, a condition that was present in five (31%) of the subjects with a normal thyroid volume (P < 0.05). Seven (23.3%) cases of subclinical hypothyroidism and one (3.3%) case of overt hypothyroidism were identified. Three (10%) patients were positive for thyroid auto-antibodies. Of the patients with overt and subclinical hypothyroidism, five out of eight (62.5%) patients showed thyroid hypoplasia. CONCLUSIONS: This study confirms the presence of alterations of thyroid function in 22q11DS, and also suggests a frequent occurrence of abnormalities in thyroid morphology in these subjects. Patients with 22q11DS should be monitored for thyroid function, and thyroid ultrasound screening should be considered, especially in those patients with changes in thyroid function or congenital heart malformations. The possible relationship between developmental abnormalities in the heart and the thyroid gland should be confirmed.