OBJECTIVE: Congenital isolated ACTH deficiency (IAD) is a rare inherited disorder that is clinically and genetically heterogeneous. Patients are characterised by low or absent cortisol production secondary to low plasma ACTH despite normal secretion of other pituitary hormones and the absence of structural pituitary defects. Onset may occur in the neonatal period, but may first be observed in later childhood. Recently, mutations in the TPIT gene, a T-box factor selectively expressed in developing corticotroph cells, have been found in cases of early-onset IAD. DESIGN: Here we report the screening of the TPIT gene in seven patients with IAD, four of whom had neonatal onset. METHODS: Genomic DNA was extracted and the sequences of the 8 TPIT exons and their intron/exon junctions were determined by automated sequencing. RESULTS: Two siblings with early-onset IAD were both compound heterozygotes for mutations in exons 2 and 6. The missense mutation (Met86Arg) in exon 2 within the T-box (or DNA binding domain) is predicted to disrupt DNA binding. A frameshift mutation in exon 6 (782delA) introduces a premature stop codon and is likely to lead to a non-functional truncated protein. No nucleotide changes were observed in exonic sequences in the other two early- or the three later-onset cases. Fifteen single nucleotide polymorphisms that were not predicted to change the TPIT transcript were also detected. CONCLUSIONS: These findings provide a further illustration of the genetic heterogeneity of IAD and are highly suggestive of one or more other genes being implicated in this disorder.
LA Metherell, MO Savage, M Dattani, J Walker, PE Clayton, IS Farooqi, and AJ Clark
S R Ali, J Bryce, M Cools, M Korbonits, J G Beun, D Taruscio, T Danne, M Dattani, O M Dekkers, A Linglart, I Netchine, A Nordenstrom, A Patocs, L Persani, N Reisch, A Smyth, Z Sumnik, W E Visser, O Hiort, A M Pereira, S F Ahmed, and on behalf of Endo-ERN
To identify cross-border international registries for rare endocrine conditions that are led from Europe and to understand the extent of engagement with these registries within a network of reference centres (RCs) for rare endocrine conditions.
Database search of international registries and a survey of RCs in the European Reference Network for rare endocrine conditions (Endo-ERN) with an overall response rate of 82%.
Of the 42 conditions with orphacodes currently covered within Endo-ERN, international registries exist for 32 (76%). Of 27 registries identified in the Orphanet and RD-Connect databases, Endo-ERN RCs were aware of 11 (41%). Of 21 registries identified by the RC, RD-Connect and Orphanet did not have a record of 10 (48%). Of the 29 glucose RCs, the awareness and participation rate in an international registry was highest for rare diabetes at 75 and 56% respectively. Of the 37 sex development RCs, the corresponding rates were highest for disorders of sex development at 70 and 52%. Of the 33 adrenal RCs, the rates were highest for adrenocortical tumours at 68 and 43%. Of the 43 pituitary RCs, the rates were highest for pituitary adenomas at 43 and 29%. Of the 31 genetic tumour RCs, the rates were highest for MEN1 at 26 and 9%. For the remaining conditions, awareness and participation in registries was less than 25%.
Although there is a need to develop new registries for rare endocrine conditions, there is a more immediate need to improve the awareness and participation in existing registries.
Louise C Gregory, Peter Gergics, Marilena Nakaguma, Hironori Bando, Giuseppa Patti, Mark J McCabe, Qing Fang, Qianyi Ma, Ayse Bilge Ozel, Jun Z Li, Michele Moreira Poina, Alexander A L Jorge, Anna F Figueredo Benedetti, Antonio M Lerario, Ivo J P Arnhold, Berenice B Mendonca, Mohamad Maghnie, Sally A Camper, Luciani R S Carvalho, and Mehul T Dattani
The transcription factor OTX2is implicated in ocular, craniofacial, and pituitary development.
We aimed to establish the contribution of OTX2 mutations in congenital hypopituitarism patients with/without eye abnormalities, study functional consequences, and establish OTX2 expression in the human brain, with a view to investigate the mechanism of action.
We screened patients from the UK (n = 103), international centres (n = 24), and Brazil (n = 282); 145 were within the septo-optic dysplasia spectrum, and 264 had no eye phenotype. Transactivation ability of OTX2 variants was analysed in murine hypothalamic GT1-7 neurons. In situ hybridization was performed on human embryonic brain sections. Genetically engineered mice were generated with a series of C-terminal OTX2 variants.
Two chromosomal deletions and six haploinsufficient mutations were identified in individuals with eye abnormalities; an affected relative of one patient harboured the same mutation without an ocular phenotype. OTX2 truncations led to significant transactivation reduction. A missense variant was identified in another patient without eye abnormalities; however, studies revealed it was most likely not causative. In the mouse, truncations proximal to aa219 caused anophthalmia, while distal truncations and the missense variant were tolerated. During human embryogenesis, OTX2 was expressed in the posterior pituitary, retina, ear, thalamus, choroid plexus, and partially in the hypothalamus, but not in the anterior pituitary.
OTX2 mutations are rarely associated with hypopituitarism in isolation without eye abnormalities, and may be variably penetrant, even within the same pedigree. Our data suggest that the endocrine phenotypes in patients with OTX2 mutations are of hypothalamic origin.