title: Prevalence of hypocalcaemia and its associated features in 22q11·2 deletion syndrome.
abstract: 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.
authors.affiliation: Clinical Genetics Research Program, Centre for Addiction and Mental Health, Toronto, ON, Canada.
authors.forename: Evelyn Ning Man
authors.initials: EN
authors.lastname: Cheung
authors.forename: Susan R
authors.initials: SR
authors.lastname: George
authors.forename: Gary A
authors.initials: GA
authors.lastname: Costain
authors.forename: Danielle M
authors.initials: DM
authors.lastname: Andrade
authors.forename: Eva W C
authors.initials: EW
authors.lastname: Chow
authors.forename: Candice K
authors.initials: CK
authors.lastname: Silversides
authors.forename: Anne S
authors.initials: AS
authors.lastname: Bassett
mesh_terms: D000328:Adult; D004062:DiGeorge Syndrome / Q000453:epidemiology* / Q000503:physiopathology; D005260:Female; D006801:Humans; D006996:Hypocalcemia / Q000453:epidemiology* / Q000503:physiopathology; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D012189:Retrospective Studies
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