Prevalence of hypocalcaemia and its associated features in 22q11·2 deletion syndrome

BACKGROUND: 22q11·2 deletion syndrome (22q11·2DS) is a relatively common yet under-recognized genetic syndrome that may present with endocrine features. We aimed to address the factors that contribute to the high prevalence of hypocalcaemia. METHODS: We investigated hypocalcaemia in a well-characterized sample of 138 adults with 22q11·2DS (65 m, 73 F; mean age 34·2, SD 11·8, years) using laboratory studies and lifelong medical records. Logistic regression modelling was used to identify features associated with lifetime prevalence of hypocalcaemia. RESULTS: Of the total sample, 111 (80·4%) had a lifetime history of hypocalcaemia. Eleven (84·6%) of 13 subjects with neonatal hypocalcaemia had documented recurrence of hypocalcaemia. Lifetime history of hypocalcaemia was associated with lifetime prevalence of hypoparathyroidism (P < 0·0001) and hypothyroidism (P = 0·04), as statistically independent factors. Hypomagnesaemia was associated with concurrent hypocalcaemic measurements, especially in the presence of concurrent hypoparathyroidism (P = 0·02). CONCLUSIONS: The results suggest that, in addition to the major effect of hypoparathyroidism, hypothyroidism may play a role in hypocalcaemia in 22q11·2DS and that there is a high recurrence rate of neonatal hypocalcaemia. Hypomagnesaemia may contribute to hypocalcaemia by further suppressing parathyroid hormone (PTH). Although further studies are needed, the findings support regular lifelong follow-up of calcium, magnesium, PTH and TSH levels in patients with 22q11·2DS. At any age, hypocalcaemia with hypoparathyroidism and/or hypothyroidism may suggest a diagnosis of 22q11·2DS.