ESPE Abstracts

Background: Loss of function mutations in SGPL1, a key component of sphingolipid metabolism, are associated with accumulation of sphingolipid intermediates giving rise to a multisystemic disease incorporating primary adrenal insufficiency (PAI) and progressive renal and neurological disease. Sphingolipids are implicated in mitochondrial apoptosis via induction of mitochondrial outer membrane permeabilization, cytosolic release of inter-membranal cytochrome c and activ...

Background: Pathogenic IGFI gene mutations causing childhood growth failure are rare. Only 5 autosomal recessive mutations, one IGFI copy number variant and 2 heterozygous frameshift mutations are reported. Heterozygous missense IGFI mutations have not previously been described.Objectives: To identify and functionally characterise a novel missense IGFI variant in a patient with postnat...

Background: SGPL1 deficiency is associated with a pathological accumulation of sphingolipid intermediates and a multi-systemic condition incorporating primary adrenal insufficiency. Sphingolipid intermediates such as ceramide, sphingosine and sphingosine 1-phosphate are postulated to act as modulators of the steroidogenic pathway, often acting as second messengers altering downstream expression of steroid responsive transcriptional elements. Ceramide and sphin...

Background: Growth hormone insensitivity (GHI) encompasses normal/elevated growth hormone (GH), low IGF-I levels and growth restriction. Non-classical/mild-moderate GHI is an emerging entity which is poorly characterised, and, in many subjects, the underlying cause is unclear. Heterozygous dominant negative (DN) variants located in the intracellular/transmembrane domain of the GH receptor (GHR) cause a ‘non-classical’ GHI phenotype.<p class="abst...

Loss of function mutations in SGPL1 (sphingosine-1-phosphate lyase) are associated with a syndromic form of primary adrenal insufficiency. A third of affected male individuals also have evidence of early primary gonadal insufficiency, with an undervirilised phenotype at birth. SGPL1 carries out irreversible breakdown of the signalling molecule sphingosine-1-phosphate (S1P) and deficiency leads to accumulation of S1P and other upstream sphingolipid intermediates to var...

Background: Silver Russell syndrome (SRS) is genetically heterogenous and around 30% of patients with clinical SRS have no genetic diagnosis. Mutations in HMGA2 have recently been identified causing growth failure and an SRS-like phenotype. Despite strong evidence of the crucial role of HMGA2 in growth across species, the mechanism of action of HMGA2 in human linear growth is unclear.Objective:...

Objectives: The homozygous GHR pseudoexon (6ψ) mutation leads to aberrant splicing of the GHR gene with clinical and biochemical heterogeneity. We investigated whether the phenotypic variability could be explained by transcript heterogeneity i.e. ratio of abnormal (6ψ GHR) to normal (WT GHR) transcripts and/or the presence of concurrent defects in other short stature (SS) genes.Methods: 6&#968...

Background: Noonan Syndrome (NS) can overlap clinically and biochemically with growth hormone insensitivity [GHI; short stature (SS), low IGF-I and normal/elevated GH levels]. Mutations in multiple genes regulating RAS/MAPK pathway have been identified in NS including LZTR1 variants. Function of LZTR1 is poorly understood and its role in growth retardation is unknown.Objectives: To functionally characte...

Context: Severe forms of growth hormone insensitivity (GHI) are characterised by extreme short stature, dysmorphism and metabolic anomalies. They are classically caused by homozygous or compound heterozygous mutations of the growth hormone receptor gene (GHR). Genetic analysis traditionally focuses on the exonic regions of genes that encode proteins rather than the intervening non-coding sequences. These seldom explored non-coding regions may harbour ...