ESPE Abstracts

Background: Pseudohypoparathyroidism type 1b (PHP1b) is caused by epigenetic errors on the maternal GNAS allele at differentially methylated regions (DMRs) associated with exons A/B, XL, and NESP that lead to reduced production of Gαs transcripts most notably in the renal proximal tubule and thyroid follicular cells. Most PHP1b cases appear sporadically, few of which can be explained by paternal uniparental disomy involving chromosome 20q, leading to global methy...

Background: Pseudohypoparathyroidism type 1a (PHP1a) is characterized by Albright hereditary osteodystrophy (AHO) and multi-hormone resistance, most commonly to parathyroid hormone (PTH) and thyroid-stimulating hormone. This rare disorder is caused by inactivating mutations involving exons 1–13 of the imprinted GNAS gene that encodes the alpha-subunit of the stimulatory G protein (Gαs). Due to paternal imprinting of Gαs transcripts, GNAS mutati...

Background: Hypophosphatemic rickets (HR) is most commonly X-linked or autosomal dominant, but autosomal recessive (AR) forms have been described. ARHR1 (DMP1) and ARHR2 (ENPP1) share identical biochemical characteristics of excessive renal phosphate wasting due to increased circulating levels of the phosphatonin FGF23 and low serum levels of 1,25(OH)2D. By contrast, in hereditary hypophosphatemic rickets with hypercalciuria (HHRH) phosphaturia is ...

Background: Hypoparathyroidism may manifest either as an isolated disorder or as a component of a more complex syndrome. Molecular genetic studies indicate that mutations in PTH, CASR, GCM2 and GNA11 are causes of isolated hypoparathyroidism (IH) and mutations in GATA3, TBCE, FAM111A, AIRE and TBX1 are associated with different complex syndromes with hypoparathyroidism.Objec...

Background: Generalized lymphatic anomaly (GLA) is a rare congenital disorder characterized by aggressive proliferation of dilated lymphatic vessels. The etiology of GLA is poorly understood.Objective and hypotheses: To identify the underlying genetic basis for GLA.Method: Exome sequencing (ES) was performed in two families, including a multigenerational family (family-1) with six affected members. RNA-seq was performed on skin bio...

Background: The genetic etiology of Type 1 Diabetes (T1D) is well recognized, with over 60 loci being identified to date, mainly through genome-wide association studies (GWAS). Most of these genetic associations involve common variants, while a sizable portion of the missing heritability of T1D could be attributed to unidentified rare single nucleotide polymorphisms (SNPs) (minor allele frequency (MAF) < 5%). The recent availability of large human whole genome sequencing d...