Congenital Hyperinsulinemia of Infancy: Role of Molecular Testing in Management and Genetic Counseling

Congenital hyperinsulinemia (CHI) is a genetically and clinically heterogenous disorder. In addition to the standard care of management of the proband, genetic counseling regarding the risk of recurrence in the future siblings is an important part in the management of the disorder. The counseling needs identification of accurate etiology and is challenging due to the complexity of the molecular mechanisms of CHI. This case highlights the importance of molecular testing which not only helped in planning the management of the proband with CHI but also helped in providing genetic counseling for which the family had consulted the medical genetics department.

Analysis of clinical and genetic characteristics of Chinese children with congenital hyperinsulinemia that is spontaneously relieved

OBJECTIVE

This study aimed to analyze the clinical and genetic characteristics of Chinese children with congenital hyperinsulinemia (CHI) that is spontaneously relieved.

METHODS

The patient group comprised 200 children with CHI that were treated at the Beijing Children's Hospital from January 2006 to December 2018. The patients were divided into two groups according to their prognosis: the spontaneous remission group (n = 92) and the nonspontaneous remission group (n = 108). The clinical characteristics, pathogenic genes, diagnosis and treatment process, and follow-up data of both groups were analyzed retrospectively.

RESULTS

Of the 200 children with CHI, 92 achieved spontaneous remission. The age of spontaneous remission was between one month and nine years, and 47 of the children were relieved before the age of one year. The median age of onset was 85 days (range: 1-2825 days) in the spontaneous remission group and 2 days (range: 1-210 days) in the nonspontaneous remission group (P < 0.05). The mean birth weight was 3.44 ± 0.76 kg for the spontaneous remission group and 3.95 ± 0.75 kg for the nonspontaneous remission group (P < 0.05). Of the 92 children in the spontaneous remission group, 65 were treated with diazoxide with effective rate of 81.5% (53/65). In 12 cases in which diazoxide treatment failed, octreotide was used with an effective rate of 83.3% (10/12). Of the 108 children in the nonspontaneous remission group, 88 were treated with diazoxide with an effective rate of 43.2 % (38/88), and 29 children were treated with octreotide with an effective rate of 48.28% (14/29). Of the 30 children in the spontaneous remission group that underwent mutation analysis of CHI-related pathogenic genes, 10 children (10/30, 33.3%) carried mutations. Of the 48 children in the nonspontaneous remission group that underwent mutation analysis of CHI-related pathogenic genes, 37 children (37/48, 77.1%) were found to carry mutations. All of the differences in the indices mentioned above were statistically significant.

CONCLUSIONS

The rate of spontaneous remission of CHI was significantly higher in children with late age of CHI onset, light birth weight, effective diazoxide treatment, and no common pathogenic gene mutations. Spontaneous remission was also possible for a small number of children that carried mutations in the ABCC and KCNJ11 genes and in whom diazoxide treatment failed.