Inheritance of a paternal ABCC8 variant and maternal loss of heterozygosity at 11p15 retrospectively unmasks the etiology in a case of Congenital hyperinsulinism

The Power of Clinical Diagnosis for Deciphering Complex Genetic Mechanisms in Rare Diseases

Complex genetic disease mechanisms, such as structural or non-coding variants, currently pose a substantial difficulty in frontline diagnostic tests. They thus may account for most unsolved rare disease patients regardless of the clinical phenotype. However, the clinical diagnosis can narrow the genetic focus to just a couple of genes for patients with well-established syndromes defined by prominent physical and/or unique biochemical phenotypes, allowing deeper analyses to consider complex genetic origin. Then, clinical-diagnosis-driven genome sequencing strategies may expedite the development of testing and analytical methods to account for complex disease mechanisms as well as to advance functional assays for the confirmation of complex variants, clinical management, and the development of new therapies.

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.