Germline ESR2 mutation predisposes to medullary thyroid carcinoma and causes up-regulation of RET expression.

Familial medullary thyroid cancer (MTC) and its precursor, C cell hyperplasia (CCH), is associated with germline RET mutations causing multiple endocrine neoplasia type 2. However, some rare families with apparent MTC/CCH predisposition do not have a detectable RET mutation. To identify novel MTC/CCH predisposition genes we undertook exome resequencing studies in a family with apparent predisposition to MTC/CCH and no identifiable RET mutation. We identified a novel ESR2 frameshift mutation, c.948delT, which segregated with histological diagnosis following thyroid surgery in family members and demonstrated loss of ESR2-encoded ERß expression in the MTC tumour. ERα and ERß form heterodimers binding DNA at specific oestrogen-responsive elements (EREs) to regulate gene transcription. ERß represses ERα-mediated activation of the ERE and the RET promoter contains three EREs. In vitro, we showed that ESR2 c.948delT results in unopposed ERα mediated increased cellular proliferation, activation of the ERE and increased RET expression. In vivo, immunostaining of CCH and MTC using an anti-RET antibody demonstrated increased RET expression. Together these findings identify germline ESR2 mutation as a novel cause of familial MTC/CCH and provide important insights into a novel mechanism causing increased RET expression in tumourigenesis.

Treating congenital adrenal hyperplasia.

Genettreating congenital adrenal hyperplasia.ic alterations associated with rare endocrine diseases disrupt the body's normal chemical communication system. Faulty genes can affect any part of the hormone pathway by altering the way the body recognises a hormone, or how a hormone acts on a target organ. One example is congenital adrenal hyperplasia. CAH results from an inherited alteration in a gene that blocks an essential enzyme (usually 21-hydroxylase) in the adrenal hormone pathway. Synthesis of cortisol (the "stress" hormone) and aldosterone, which regulates the blood pressure through sodium, potassium and fluid balance, is impaired or absent. The adrenal glands enlarge as they work harder to correct the imbalance, resulting in the overproduction of androgens (male hormones); the more severe the enzyme block, the greater the male hormone production. In 95% of people with CAH, it is due to an alteration in the 21-hydroxylase gene, which is recessively inherited (Perrin et al, 2000). One in 55 people is a carrier for CAH (Baumgartner-Parzer et al, 2005).

Rare diseases: what do you need to know?

This six-part series on rare diseases aims to increase awareness and offer advice on how nurses can help patients. Part 1 uses a case study to illustrate the complexity of caring for people with rare diseases and provides pointers on how the care of this patient group can be improved.

J chain in the nurse shark: implications for function in a lower vertebrate.

J chain is a small polypeptide covalently attached to polymeric IgA and IgM. In humans and mice, it plays a role in binding Ig to the polymeric Ig receptor for transport into secretions. The putative orthologue of mammalian J chain has been identified in the nurse shark by sequence analysis of cDNA and the polypeptide isolated from IgM. Conservation with J chains from other species is relatively poor, especially in the carboxyl-terminal portion, and, unlike other J chains, the shark protein is not acidic. The only highly conserved segment in all known J chains is a block of residues surrounding an N-linked glycosylation site. Of the eight half-cystine residues that are conserved in mammalian J chains, three are lacking in the nurse shark, including two in the carboxyl-terminal segment that have been reported to be required for binding of human J chain-containing IgA to secretory component. Taken together with these data, the relative abundance of J chain transcripts in the spleen and their absence in the spiral valve (intestine) suggest that J chain in nurse sharks may not have a role in Ig secretion. Analysis of J chain sequences in diverse species is in agreement with accepted phylogenetic relationships, with the exception of the earthworm, suggesting that the reported presence of J chain in invertebrates should be reassessed.