Pearson syndrome (PS), a rare multisystem mitochondrial disorder caused by single large-scale DNA (mtDNA) deletions (SLSMDs), commonly presents with anaemia in infancy.1, 2 Progressive multi-organ dysfunction such as lactic acidosis, pancreatic and renal dysfunction, failure to thrive endocrine disorders can develop during the course.1, 3 Interestingly, often resolves spontaneously; frequency p...

For any generalized linear model, the Pearson goodness of fit statistic is the score test statistic for testing the current model against the saturated model. The relationship between the Pearson statistic and the residual deviance is therefore the relationship between the score test and the likelihood ratio test statistics, and this clarifies the role of the Pearson statistic in generalized li...