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Congenital hyperinsulinism (CHI) causes hypoglycemia due to irregular insulin secretion. In infants, a rapid diagnosis and appropriate management to avoid severe hypoglycemia is mandatory. CHI is a heterogeneous condition at the clinical and genetic level, and disease-causing genes have been identified in about half of the patients. The majority of mutations have been identified in the ABCC8 and KCNJ11 genes encoding subunits of the K_ATP channel responsible for two distinct histological forms. The diffuse form is caused by autosomal recessive or dominant inherited mutations, whereas the focal form is caused by a paternally transmitted recessive mutation and a second somatic event. We report on an unselected cohort of 136 unrelated patients from the German CHI registry. Mutations in either the ABCC8 or KCNJ11 gene were identified in 61 of these patients (45%). In total, 64 different mutations including 38 novel ones were detected in this cohort. We observed biparental (recessive) inheritance in 34% of mutation-positive patients, dominant inheritance in 11% and paternal transmission of a mutation associated with a focal CHI type in 38%. In addition, we observed inheritance patterns that do not exactly follow the classical recessive or dominant mode, further adding to the genetic complexity of this disease.

Background/Aims: Congenital hyperinsulinism (CHI) is a rare disease characterized by recurrent severe hypoglycemia. In the diffuse form of CHI, pharmacotherapy is the preferred choice of treatment. Long-acting somatostatin analogues have been used in children as off-label medication. However, the efficacy, outcomes, and adverse effect profiles of long-acting somatostatin analogues have not been described in multicentered studies. The aim of this retrospective study is to summarize the experience with long-acting somatostatin analogues in a large group of children with CHI. Methods: Data were obtained retrospectively from 27 patients with CHI who received long-acting somatostatin analogues in 6 different centers in Europe. These included information on glycemic stability, auxology, and adverse effect profile in clinical follow-up assessments. Results: Blood glucose control improved in most patients (89%). No life-threatening side effects occurred. Thirteen patients (48%) experienced side effects; in 3 patients (11%), the side effects were the main reason for discontinuation of the treatment. The most frequent side effect was elevated liver enzymes (n = 10, 37%). Conclusion: Long-acting somatostatin analogues are effective in glycemic control of patients with CHI. However, in 37% of all patients increased liver enzymes were observed. It is important to monitor liver function in all patients receiving long-acting somatostatin analogue therapy.

Background: Congenital hyperinsulinism (CHI) is hallmarked by persistent hypoketotic hypoglycemia in infancy. In the majority of all patients, CHI is caused by mutations in the KATP channel genes ABCC8 and KCNJ11, but other genes in the insulin-regulatory pathway have also been described. Repeated episodes of hypoglycemia include an increased risk of seizures and intellectual disability. So far, controlled psychometric studies on cognitive, motor, speech, and social-emotional outcome of CHI patients are missing. Until now, neurodevelopmental long-term outcome in CHI patients has only been measured by questionnaires, self-, parental-, or caregiver-administered instruments. Methods: This is a prospective study of 60 patients (median age 3.3 years, range 3 months to 57 years): 48 with a diffuse, 9 with a focal, and 3 with an atypical histology. Neurodevelopmental outcome was assessed using standardized psychological tests and questionnaires. Results: 28 of 60 patients showed developmental delay (46.7%). 9 of 57 patients had cognitive deficits (15.8%), 7 of 26 patients had speech problems (26.9%), and 17 of 44 patients had motor problems (38.6%). In 5 of 53 patients, social-emotional problems were reported. Outcome and the underlying genetic defect were not correlated. Conclusions: Motor problems seem to be prominent in CHI patients. Despite a high incidence of developmental delay, a permanent cognitive defect was only detectable in 9 of 58 patients.

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