HIDEA syndrome: A new case report highlighting similarities with ROHHAD syndrome.

peer reviewedContext: ROHHAD syndrome presents a significant resemblance to HIDEA syndrome. The latter is caused by biallelic loss-of-function variants in the P4HTM gene and encompasses hypotonia, intellectual disabilities, eye abnormalities, hypoventilation, and dysautonomia. We report the first patient identified with HIDEA syndrome from our ROHHAD cohort. Clinical case: Our patient was a 21-month-old girl who had a history of severe respiratory infections requiring intensive care, hypotonia, abnormal eye movements, and rapid weight gain. Polysomnography identified severe central hypoventilation. During her follow-up, a significant psychomotor delay and the absence of language were gradually observed. The prolactin levels were initially increased. Hypothermia was reported at 4 years. Exome sequencing identified a new homozygous truncating P4HTM variant. Discussion: Our patient met the diagnosis criteria for ROHHAD, which included rapid weight gain, central hypoventilation appearing after 1.5 years of age, hyperprolactinemia suggesting hypothalamic dysfunction, and autonomic dysfunction manifesting as strabismus and hypothermia. However, she also presented with severe neurodevelopmental delay, which is not a classic feature of ROHHAD syndrome. HIDEA syndrome presents similarities with ROHHAD, including hypoventilation, obesity, and dysautonomia. To date, only 14% of endocrinological disturbances have been reported in HIDEA patients. Better delineation of both syndromes is required to investigate the eventual involvement of P4HTM, a regulator of calcium dynamics and gliotransmission, in ROHHAD patients. Conclusion: In the case of clinical evidence of ROHHAD in a child with abnormal neurological development or eye abnormalities, we suggest that the P4HTM gene be systematically interrogated in addition to the analysis of the PHOX2B gene. A better delineation of the natural history of HIDEA is required to allow further comparisons between features of HIDEA and ROHHAD. The clinical similarities could potentially orient some molecular hypotheses in the field of ROHHAD research

ROHHAD syndrome without rapid-onset obesity: A diagnosis challenge

peer reviewedBackgroundROHHAD syndrome (Rapid-onset Obesity with Hypothalamic dysfunction, Hypoventilation and Autonomic Dysregulation) is rare. Rapid-onset morbid obesity is usually the first recognizable sign of this syndrome, however a subset of patients develop ROHHAD syndrome without obesity. The prevalence of this entity is currently unknown. Alteration of respiratory control as well as dysautonomic disorders often have a fatal outcome, thus early recognition of this syndrome is essential.Material and methodsA retrospective, observational, multicenter study including all cases of ROHHAD without rapid-onset obesity diagnosed in France from 2000 to 2020.ResultsFour patients were identified. Median age at diagnosis was 8 years 10 months. Median body mass index was 17.4 kg/m2. Signs of autonomic dysfunction presented first, followed by hypothalamic disorders. All four patients had sleep apnea syndrome. Hypoventilation led to the diagnosis. Three of the four children received ventilatory support, all four received hormone replacement therapy, and two received psychotropic treatment. One child in our cohort died at 2 years 10 months old. For the three surviving patients, median duration of follow-up was 7.4 years.ConclusionROHHAD syndrome without rapid-onset obesity is a particular entity, appearing later than ROHHAD with obesity. This entity should be considered in the presence of dysautonomia disorders without brain damage. Likewise, the occurrence of a hypothalamic syndrome with no identified etiology requires a sleep study to search for apnea and hypoventilation. The identification of ROHHAD syndrome without rapid-onset obesity is a clinical challenge, with major implications for patient prognosis

Novel Loss of Function Variant in BCKDK Causes a Treatable Developmental and Epileptic Encephalopathy.

peer reviewedBranched-chain amino acids (BCAA) are essential amino acids playing crucial roles in protein synthesis and brain neurotransmission. Branched-chain ketoacid dehydrogenase (BCKDH), the flux-generating step of BCAA catabolism, is tightly regulated by reversible phosphorylation of its E1α-subunit. BCKDK is the kinase responsible for the phosphorylation-mediated inactivation of BCKDH. In three siblings with severe developmental delays, microcephaly, autism spectrum disorder and epileptic encephalopathy, we identified a new homozygous in-frame deletion (c.999_1001delCAC; p.Thr334del) of BCKDK. Plasma and cerebrospinal fluid concentrations of BCAA were markedly reduced. Hyperactivity of BCKDH and over-consumption of BCAA were demonstrated by functional tests in cells transfected with the mutant BCKDK. Treatment with pharmacological doses of BCAA allowed the restoring of BCAA concentrations and greatly improved seizure control. Behavioral and developmental skills of the patients improved to a lesser extent. Importantly, a retrospective review of the newborn screening results allowed the identification of a strong decrease in BCAA concentrations on dried blood spots, suggesting that BCKDK is a new treatable metabolic disorder probably amenable to newborn screening programs

Genetic and phenotypic spectrum associated with IFIH1 gain-of-function

IFIH1 gain-of-function has been reported as a cause of a type I interferonopathy encompassing a spectrum of autoinflammatory phenotypes including Aicardi–Goutières syndrome and Singleton Merten syndrome. Ascertaining patients through a European and North American collaboration, we set out to describe the molecular, clinical and interferon status of a cohort of individuals with pathogenic heterozygous mutations in IFIH1. We identified 74 individuals from 51 families segregating a total of 27 likely pathogenic mutations in IFIH1. Ten adult individuals, 13.5% of all mutation carriers, were clinically asymptomatic (with seven of these aged over 50 years). All mutations were associated with enhanced type I interferon signaling, including six variants (22%) which were predicted as benign according to multiple in silico pathogenicity programs. The identified mutations cluster close to the ATP binding region of the protein. These data confirm variable expression and nonpenetrance as important characteristics of the IFIH1 genotype, a consistent association with enhanced type I interferon signaling, and a common mutational mechanism involving increased RNA binding affinity or decreased efficiency of ATP hydrolysis and filament disassembly rate

Glucose-galactose transporter DEFICIENCY: a diagnosis based on clinical observations.

Dehydration and major diarrhea in young infants is mainly linked to infectious diseases. However in case leading to denutrition and growth retardation, metabolic causes or malabsorption should be evocated. We report here the case of a few days old infant admitted for early recurrence of liquid stools and vomiting. XX is born at term (3450 grams, 51 cm) after an uneventful pregnancy. Consanguinity has been reported in the family. He was breastfed but presented rapidly liquid stools and vomiting. At 10 days old he was first admitted for dehydration, loss of weight below his birth weight (2900 grams) and severe hypernatremia. Semi elementary diet led to some improvement but he was readmitted at the age of one month for similar even worse symptoms including abdominal distension and explosive stools. Complementary investigations have excluded infection, parasitosis, malformation and immune deficits. Different diet formulas were tried with no significant benefit what led to the placement of parenteral nutrition thanks to which weight was gained. Hypothesis of peculiar carbohydrate malabsorption was made and the following tests have been carried out: -Clinitest: presence of reducing substances in the stools. -Lactose Breath test: between 15 and 90 ppm H2 with a peak value at 90 ppm H2 after 90 minutes. -Duodenal biopsy: normal histology; normal activity of lactase, maltase, saccharase-isomaltase. Considering the normality of these enzyme activities, hypothesis of “Na-dependant glucose-galactose transporter” deficit was put forward. This was confirmed according to the results of HGPO and glucose breath test. Search for SGTL1 gene mutation is still in progress. In conclusion despite of the huge progresses made at molecular biology level, clinical observation remain essential to the diagnosis of malabsorption. Precise reporting of the used milk formula and comparative analysis of their composition can orient the diagnosis and help to select the most accurate molecular test. Here, analyses exclude every enzyme activity deficiencies. Carbohydrate malabsorption from first days of live can be linked to a glucose-galactose transporter deficiency due to a SGLT1 mutation (chr 22). This autosomal recessive disorder has only been reported 200 times until now

How I explore childhood hypoglycemia : a report of two cases

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