ESPE Abstracts

Background: Loss of imprinting has been implicated in the pathogenesis of several human diseases. Monogenic causes of central precocious puberty (CPP) were identified in families with loss-of-function mutations in two paternally expressed imprinted genes: Makorin zinc finger 3 (MKRN3) and Delta-like 1 homolog (DLK1). The role of imprinting defects in CPP has not been described so far.Objective: To inves...

Background: Although growth hormone (GH) and the GH releasing hormone receptor (GHRHR) are known as etiologic factors in non-syndromic isolated growth hormone deficiency (IGHD), very few mutations have been identified in this rare condition (accounting for only 6–12.5% and 0–6.7% of IGHD cases depending on studies). The functional consequences of the identified variants have rarely been assessed.Objective and hypotheses: To assess the contribut...

Background: In humans, the GHN gene transcription is under the control of a Locus Control Region (LCR) enhancer, HSI, located 14.5 kb 5′ to the hGHN promoter. POU1F1, a pituitary-specific transcription factor, plays an essential role in the specification of the somatotroph, lactotroph and thyrotroph lineages and the activation of GHN, PRL and TSH gene transcription. All POU1F1 mutations so far reported have been linke...

Background: Mutations in the gene encoding LHX4, a homeodomain-containing factor with two LIM domains, are responsible for dominant hypopituitarisms with incomplete penetrance and variable expressivity. To date, only 14 unambiguous LHX4 mutations have been reported. Among those cases, 12 had an absent or ectopic posterior pituitary (EPP) and/or an abnormal sella turcica.Objective and hypotheses: To i) assess the contribution of LHX4 in combined pituitary...

Purpose: Isolated growth hormone deficiency (IGHD) is a rare condition mainly caused by mutations in GH1. The aim of this study was to assess the contribution of GHRHR mutations to IGHD in a very large cohort of patients.Methods: All GHRHR coding exons and flanking intronic regions were sequenced in 312 unrelated patients with non-syndromic IGHD. Functional consequences of all newly identified missense variants were assessed <e...

Background: Bi-allelic GHR mutations are classically responsible for Laron syndrome, a severe growth hormone (GH) resistance syndrome. A few GHR missense mutations have also been implicated in mild GH resistance or idiopathic short stature. IGFALS mutations are responsible for recessive or semi-dominant short stature with normal GH provocative test contrasting with extremely low IGF-I levels.Objective and hypotheses: To assess the contribution of GHR and...

Background: Homozygous or compound heterozygous mutations of gene CYP24A1 have recently been reported to cause idiopathic infantile hypercalcemia due to increased intestinal absorption of calcium. However, an autosomal dominant transmission with partial penetrance of the trait was also suggested.Objective and hypotheses: Evaluation of the frequency of CYP24A1 mutation and evaluation of the impact of heterozygous mutation on calcium meta...

Background: Silver-Russell syndrome (SRS) is characterized by intrauterine and postnatal growth retardation, relative macrocephaly at birth, prominent forehead, severe feeding difficulties and body asymmetry. In around 50%, it is secondary to hypomethylation at the IGF2/H19 imprinted locus on 11p15 (11p15 LOM), and in 10% to a maternal disomy of chromosome 7 (mUPD7). Mechanisms of postnatal growth failure in SRS are not well understood.Objective and hypo...

Background: Heterozygous GNAS inactivating mutations cause pseudohypoparathyroidism type Ia (PHP-Ia) when maternally inherited and pseudopseudohypoparathyroidism (PPHP)/progressive osseous heteroplasia when paternally inherited. Mutations on the paternal, but not the maternal, GNAS allele are associated with intrauterine growth retardation (IUGR). Moreover, birth weights were lower with paternal GNAS mutations affecting exons 2–13 (including XL and Gαs) than with exo...

Background: GNAS gene is a complex imprinted locus, resulting in the expression of at least four transcripts (XL, NESP55, A/B and Gsα) characterized by their specific exon 1 and common exons 2-13. While Gαs is biallelically expressed in most tissues, XL is only expressed from the paternal allele. Maternally inherited, loss-of-function mutations affecting those GNAS exons that ...