TSHB and central congenital hypothyroidism: Biallelic TSHB deletions were recently described in a Turkish patient.13 Intriguingly, one of the original Brazilian cases with a c.373delT TSHB mutation exhibited apparent uniparental inheritance; compound heterozygosity of the c.373delT mutation with a TSHB deletion would also be a plausible alternative explanation in this patient.6 P2 harbours a heterozygous TSHB deletion together with a monoallelic c.373delT mutation, suggesting that TSHB deletions may be a more common cause of isolated TSH deficiency than previously thought.