Endogenous hypercorticism in infants occurs extremely rare. The causes of Cushing’s syndrome in early childhood include space-occupying lesions and bilateral hyperplasia of the adrenal glands. ACTH-independent hypercorticism due to bilateral nodular hyperplasia of the adrenal glands in children in the first months of life is most often associated with McCune-Albright-Braitsev syndrome. This syndrome is a rare disease caused by hyperfunction of the stimulatory G-protein alpha-subunit due to somatic mutations in the GNAS gene. The McCune-Albright-Braitsev syndrome is a multicomponent disease, the clinical manifestations of which include café-au-lait spots, fibrous dysplasia, and different types of endocrine hyperfunction, among which hypercorticism is one of the rare cases. The clinical picture of Cushing’s syndrome manifested in early childhood is characterized by some peculiarities that can delay the correct diagnosis: the first manifestations include low weight and height at birth, physical retarfation in the absence of a redistribution of subcutaneous fat typical of Cushing’s syndrome, psychomotor retardation, and complications caused by immunodeficiency and hypertension. We present a case of ACTH-independent hypercorticism in an infant.

Background. Pseudohypoparathyroidism (PHP) is a heterogeneous group of disorders associated with tissue insensitivity to parathyroid hormone. PHP is characterized by genetic heterogeneity and variable phenotype. In addition to the hypocalcemic syndrome and resistance to parathyroid hormone, PHP is also characterized by phenotypic features and resistance to other hormones (TSH, LH, FSH, and GHRH), which are known as Albright Hereditary Osteodystrophy (AHO). Until recently, no analysis of large cohorts of patients with PHP has been performed in Russian literature. Objective — to examine a large cohort of patients with PHP and assess the clinical features of PHP. Material and methods. A group consisting of 32 patients with different variants of course of the disease who had been examined at the Endocrinology Research Center in 2014—2016 was analyzed. Results. Features of AHO phenotype in addition to hormonal resistance were identified in 16 (50%) patients; one of them had one feature (brachydactyly) and 15 patients had two and more features of AHO. Besides insensitivity to PTH, TSH resistance was found in 22 (68.75%) patients and one patient had resistance to PTH, TSH and LH/FSH. Hypothyroidism manifested before hypocalcaemia in 4 patients. Obesity was the first complaint in 8 patients; 5 of them had subclinical hypocalcaemia and the remaining 3 patients had an elevated PTH level with the normal level of calcium at the time of first examination. The most typical clinical signs of hypocalcaemia in 23 (72%) patients were seizures. Thirteen of them were misdiagnosed with epilepsy and had been followed by a neurologist for a period ranging between 2 months and 7 years before hypocalcaemia was revealed. Conclusions. Pseudohypoparathyroidism is a rare genetic disorder associated with resistance to parathyroid hormone, which can have a lot of other clinical features in addition to the symptoms of PTH resistance. Obesity or hypothyroidism can be the earliest manifestation of PHP preceding hypocalcaemia. Evaluation of serum calcium level is important for all pediatric patients with seizures to timely diagnose hypocalcaemia and avoid misdiagnosing.

Nephrogenic syndrome of inappropriate antidiuresis (NSIAD) is a rare X-linked disorder of water balance, which was first described in two unrelated male infants with severe symptomatic hyponatremia. NSIAD is caused by activating mutations of the arginine vasopressin receptor 2 (AVPR2) gene, resulting in impaired reabsorption of free water, which leads to increased osmolarity of urine, plasma hypo-osmolarity, and persistent hyponatremia. We report, for the first time in the domestic literature, a case of isolated euvolemic hyposmolality hyponatremia in a child with oligodipsia. Because hypocorticism and renal pathology were excluded, and there was no antidiuretic hormone hypersecretion, NSIAD was suggested. A molecular genetic study revealed a new mutation L312S, not described earlier, in the seventh transmembrane domain of the AVPR2 gene. Pathogenicity of the mutation was proved by a functional study. We provide the clinical and laboratory characteristics of SIAD and the main principles of treatment. This disease should be considered in the differential diagnosis of hyponatremia syndrome.

McCune-Albright syndrome (MAS) is a rare genetic disorder which is caused by somatic mutations in the GNAS gene. Clinical symptoms of MAS include café-au-lait skin pigmentation, fibrous dysplasia, and autonomous endocrine hyperfunction. Somatic character of the gene defects determines wide variety of syndrome manifestations, from mild forms with minimum presentation to severe conditions with aggressive course. Potential multicomponent form of the MAS syndrome necessitates the dynamic monitoring, including regular screening for possible components of the disease. Therefore, additional methods specifying the diagnosis of MAS syndrome, especially of its suppressed forms, should facilitate selection of patient management strategy and monitoring rate and/or complete exclusion of the diagnosis. Molecular genetic verification of the diagnosis may be one of these methods. Objective — the study was aimed at evaluating massive parallel sequencing (next generation sequencing, NGS) and real-time polymerase chain reaction using the TaqMan technique for detection of somatic mutations (competitive allele-specific TaqMan PCR, CAST-PCR) in the diagnosis of somatic mutations R201C and R201H in the GNAS gene based on DNA obtained from the peripheral blood. Material and methods. The study included patients diagnosed with and suspected for MAS syndrome. Molecular genetic testing of R201C and R201H mutations in the GNAS gene based on DNA extracted from peripheral blood leukocytes was carried out by Next generation sequencing (NGS) and real-time polymerase chain reaction methods using the TaqMan technique for detection of somatic mutations (competitive allele-specific TaqMan PCR, CAST-PCR). Based on clinical data, patients were divided into groups depending on the severity of the disease and the number of MAS manifestations. The results were evaluated by comparing the rate of detected molecular genetic defects in the formed groups of patients. Results. Molecular genetic study included 39 children with MAS syndrome and 6 children with suspected MAS. R201C and R201H mutations in GNAS gene were detected in 16 patients with severe to moderate MAS 16 (41%) 39. No mutations were detected in other MAS patients and patients with suspected MAS. Conclusion. NGS and CAST-PCR methods can detect the presence of mutant alleles R201C and R201H of GNAS gene in DNA samples obtained from the blood in the case of severe to moderate MAS syndrome, but they cannot be recommended for MAS diagnosis based on the peripheral blood samples in children with mild signs of the syndrome or suspected diagnosis.

McCune—Albright syndrome (MAS) is a rare multisystem disorder, classically defined by the clinical triad of fibrous dysplasia of bones (FD), café-au-lait skin spots, precocious puberty (PP) and other hyperfunctioning endocrinopathies. Diagnosis can be made if there are at least 2 of the 3 classical features. It is caused by somatic mutations of the GNAS gene encodes stimulate α-subunit of G protein (Gas). Gas is crucial for mediating effects of the lot of peptide hormones. Increased activity of Gas leads to multisystem hyperfunction. Some features are common (such as gonadotropin-independent precocious puberty) and another signs occur seldom. The clinical presentation of MAS is variable, the features occur at the different age. One of the rare feature of the MAS is Cushing’s syndrome due to bilateral adrenal hyperplasia, which usually occurs in the neonatal period. We describe clinical case of ACTH-independent hypercortisolism in the boy with MAS.