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Supplementary table and figures for 'GROWTH HORMONE RECEPTOR (GHR) 6Ω PSEUDOEXON ACTIVATION - A NOVEL CAUSE OF SEVERE GROWTH HORMONE INSENSITIVITY (GHI)' manuscript by Cottrell et al.docx. This manuscript describes a novel GHR 6Ω pseudoexon inclusion resulting in a loss of GHR function consistent with a severe Growth Hormone Insensitivity phenotype. This represents a novel mechanism of Laron syndrome and is the first deep intronic variant identified causing severe postnatal growth failure.

Objectives Lower limb deformities in children need careful orthopedic evaluation to distinguish physiological forms from pathological ones. X-linked hypophosphatemia (XLH) is a rare hereditary condition caused by PHEX gene mutations where tibial varum can be the first sign. Case presentation We report a family presenting with severe tibial varum, harbouring a rare PHEX intron mutation, c.1586+6T>C. This is the first clinical description available in literature for this variant. Despite the previous prediction of a mild phenotype in functional study, our patients showed important bone deformities, rickets and impaired growth since infancy followed by severe bone pain, hearing loss and reduced life quality in adulthood. Burosumab therapy improved biochemical and radiological findings in children and ameliorated quality of life in adults. Conclusions This case demonstrated c.1586+6T>C causes a severe XLH phenotype, responsive to Burosumab. Familial genetic screening, enlarged to intronic region analysis, when XLH is suspected, allows precocious diagnosis to start timely the appropriate treatment.

Objective To evaluate (i) the prevalence and association of euthyroid sick syndrome (ESS) [decreased FT3 and/or FT4 and normal/decreased TSH] with severity indexes of type 1 diabetes mellitus (T1DM) onset such as diabetic ketoacidosis (DKA) and kidney damage [acute kidney injury (AKI) based on KDIGO criteria, acute tubular necrosis (ATN), renal tubular damage (RTD)], (ii) relationship between clinical/metabolic parameters at T1DM onset and thyroid hormones, and (iii) ESS as a prognostic indicator of delayed recovery from kidney damage. Methods A total of 161 children with T1DM onset were included. RTD was defined by abnormal urinary beta-2-microglobulin and/or neutrophil gelatinase-associated lipocalin (NGAL) and/or tubular reabsorption of phosphate 2%. ATN was defined by RTD+AKI. Results Of 161 participants, 60 (37.3%) presented ESS. It was more prevalent in case of more severe T1DM presentation both in terms of metabolic derangement (DKA) and kidney function impairment (AKI, RTD and ATN). Only ATN, however, was associated with ESS at adjusted analysis. FT3 inversely correlated with serum triglycerides and creatinine, and urinary calcium/creatinine ratio and NGAL. Participants with euthyroidism showed earlier recovery from AKI than those with ESS. ESS spontaneously disappeared. Conclusions ESS is associated with T1DM onset severity and spontaneously disappears. ESS delayed the recovery from AKI. Impact This is the first longitudinal study describing in detail the relationship between clinical/metabolic factors at type 1 diabetes mellitus (T1DM) onset and thyroid hormones, with particular attention to the relationship between diabetic ketoacidosis (DKA)-related kidney function impairment and euthyroid sick syndrome (ESS). Participants with more severe T1DM onset presentation both in terms of metabolic derangement and kidney function impairment had an increased prevalence of ESS. Children with ESS had a slower recovery from acute kidney injury compared with those without ESS. ESS spontaneously disappeared in all participants.

Context Severe forms of growth hormone insensitivity (GHI) are characterized by extreme short stature, dysmorphism, and metabolic anomalies. Objective This work aims to identify the genetic cause of growth failure in 3 “classical” GHI individuals. Methods A novel intronic growth hormone receptor gene (GHR) variant was identified, and in vitro splicing assays confirmed aberrant splicing. A 6Ω pseudoexon GHR vector and patient fibroblast analysis assessed the consequences of the novel pseudoexon inclusion and the impact on GHR function. Results We identified a novel homozygous intronic GHR variant (g.5:42700940T > G, c.618+836T > G), 44 bp downstream of the previously recognized intronic 6Ψ GHR pseudoexon mutation in the index patient. Two siblings also harbored the novel intronic 6Ω pseudoexon GHR variant in compound heterozygosity with the known GHR c.181C > T (R43X) mutation. In vitro splicing analysis confirmed inclusion of a 151-bp mutant 6Ω pseudoexon not identified in wild-type constructs. Inclusion of the 6Ω pseudoexon causes a frameshift resulting in a nonfunctional truncated GHR lacking the transmembrane and intracellular domains. The truncated 6Ω pseudoexon protein demonstrated extracellular accumulation and diminished activation of STAT5B signaling following GH stimulation. Conclusion Novel GHR 6Ω pseudoexon inclusion results in loss of GHR function consistent with a severe GHI phenotype. This represents a novel mechanism of Laron syndrome and is the first deep intronic variant identified causing severe postnatal growth failure. The 2 kindreds originate from the same town in Campania, Southern Italy, implying common ancestry. Our findings highlight the importance of studying variation in deep intronic regions as a cause of monogenic disorders.