Adrenal hypoplasia is a rare, life-threatening congenital disorder. Here we define a new form of syndromic adrenal hypoplasia, which we propose to term MIRAGE (myelodysplasia, infection, restriction of growth, adrenal hypoplasia, genital phenotypes, and enteropathy) syndrome. By exome sequencing and follow-up studies, we identified 11 patients with adrenal hypoplasia and common extra-adrenal features harboring mutations in SAMD9. Expression of the wild-type SAMD9 protein, a facilitator of endosome fusion, caused mild growth restriction in cultured cells, whereas expression of mutants caused profound growth inhibition. Patient-derived fibroblasts had restricted growth, decreased plasma membrane EGFR expression, increased size of early endosomes, and intracellular accumulation of giant vesicles carrying a late endosome marker. Of interest, two patients developed myelodysplasitc syndrome (MDS) that was accompanied by loss of the chromosome 7 carrying the SAMD9 mutation. Considering the potent growth-restricting activity of the SAMD9 mutants, the loss of chromosome 7 presumably occurred as an adaptation to the growth-restricting condition.
The results argue against the heterozygote manifestation and suggest that the residual POR activity reflected by the R457H dosage constitutes the underlying factor for clinical variability in some features but not other features, probably due to the simplicity and complexity of POR-dependent metabolic pathways relevant to each phenotype.
The increased androsterone excretion during early infancy, as compared with the etiocholanolone and 11-hydroxyandrosterone excretions in the same period, suggests the presence of the backdoor pathway in PORD.
Antley-Bixler syndrome (ABS) is characterized by skeletal defects including craniosynostosis and radiohumeral synostosis. Although mutations in the FGFR2 gene have been found in some patients called ABS, genetic heterogeneity of this syndrome has been proposed. We have previously reported three ABS patients with unique abnormalities in steroidogenesis (apparent decreased activity of 17alpha-hydroxylase, 17,20-lyase, and 21-hydroxylase). Decreased activity of lanosterol 14alpha-demethylase has also been described in an ABS patient. Since all these enzymes require cytochrome P450 oxidoreductase (encoded by POR) as an electron donor, we studied POR in two unrelated ABS patients with abnormal steroidogenesis. Direct sequencing of POR revealed that both patients had compound heterozygous mutations (1329insC and R454H in a male patient, 1698insC and R454H in a female patient). The two insertional mutations were assumed to generate truncated and unstable mRNAs. The R454H mutation was assumed to be deleterious because the R454 resides in the FAD-binding domain and is highly conserved among diverse species. Our results demonstrate that mutations in POR cause the ABS phenotype with autosomal recessive inheritance and with characteristic abnormalities in steroidogenesis.
Using a population-based sample, we confirmed that a minor subset of CH patients has transcription factor mutations, but they are rare. In our cohort, PAX8 mutations were the leading cause of such a rare condition.
Antley-Bixler syndrome (ABS, MIM 207410) is a skeletal abnormality syndrome primarily affecting head and limbs. Little is known of the origin of the condition but inactivating mutations in the fibroblast growth factor receptor (FGFR2) has been found in some patients. Genital ambiguity is seen occasionally in this condition, suggesting possible disordered steroidogenesis in early pregnancy. We report the steroid excretion of eight patients diagnosed with the syndrome and one with a related condition, a mild phenotype of the disorder since skeletal and genital abnormalities were not evident. The steroid excretion pattern was consistent and very distinctive in all nine patients. Metabolites of the two primary precursors of steroid hormones, pregnenolone and progesterone, were elevated as were the classical diagnostic metabolites for 17- and 21-hydroxylase deficiencies. Cortisol production was typically within the normal range but generally had blunted response to ACTH. Androgen metabolite excretion tends to be low in patients over 2 months of age, but may be elevated in the newborn period. The metabolome suggested attenuated steroid hydroxylation (including 17,20-lyase activity) although underlying cause is yet to be established. Mutations in CYP17 and CYP21 have not been found and currently the prime suspect is an abnormality in an essential redox partner (P450 oxidoreductase). This paper proposes use of the distinctive steroid metabolome as the primary biochemical parameter for diagnosis of ABS, at least the form not associated with FGFR2 mutations.
We suggest that hypogonadism, GH deficiency, and hypothyroidism could be possible endocrinological defects in patients with CHD7 mutations and that olfactory bulb hypoplasia as well as semicircular canal aplasia should be considered as a major sign for CHARGE syndrome and recommend a computed tomography scan of the temporal bone and magnetic resonance imaging study of the olfactory bulb region.
Abstract.Congenital hyperinsulinism is a rare condition, and following recent advances in
diagnosis and treatment, it was considered necessary to formulate evidence-based clinical
practice guidelines reflecting the most recent progress, to guide the practice of
neonatologists, pediatric endocrinologists, general pediatricians, and pediatric surgeons.
These guidelines cover a range of aspects, including general features of congenital
hyperinsulinism, diagnostic criteria and tools for diagnosis, first- and second-line
medical treatment, criteria for and details of surgical treatment, and future
perspectives. These guidelines were generated as a collaborative effort between The
Japanese Society for Pediatric Endocrinology and The Japanese Society of Pediatric
Surgeons, and followed the official procedures of guideline generation to identify
important clinical questions, perform a systematic literature review (April 2016), assess
the evidence level of each paper, formulate the guidelines, and obtain public
comments.
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