Inclusion Criteria:  Males or females with a confirmed diagnosis of childhood onset (<16 years) PCM Males or females with childhood onset (<16 years) of a rare inherited cardiac condition likely to be a monogenic condition.  Capacity for parents to provide informed consent. Genotype negative following local standard diagnostic ICC gene panel. Family members of patients with ICC, both affected and unaffected.  Exclusion Criteria:  Parents who lack capacity to provide consent on behalf of their children/themselves.  Onset over 16 years. Significant teratogen exposure (including maternal diabetes) likely to contribute to cardiac dysfunction (following discussion with Cardiologist) Significant coronary heart disease likely to contribute to cardiac dysfunction (following discussion with Cardiologist) Other secondary causes of cardiac dysfunction likely to explain the phenotype of the patient Patients with a confirmed genetic diagnosis (patients with variants of uncertain significance are not excluded).