Misdiagnosis is a major problem at all levels of health care causing unnecessary pain or even death as it prevents efficient, timely, and adequate treatment. In the case of infectious diseases, for instance, identification of the wrong pathogen might lead to incorrect prescription of antibiotics. While reliable data on the full extent of misdiagnosis are elusive, some evidence of the problem's scale came from a meta‐analysis of deaths within US intensive care units (ICUs), which found that 40,500 adult patients in the USA may die each year as a result of a misdiagnosis [1]. An earlier, more comprehensive, study based on searching the MEDLINE (1950–2007) and EMBASE (1980–2007) electronic databases for articles about diagnostic error or delay in primary care also found that misdiagnosis was a significant issue, although the reasons varied with each condition [2]. Moreover, many diseases, in particular rare diseases, are hard to diagnose as physicians are often unfamiliar with the symptoms; alternatively, the symptoms might be vague or untypical, as can happen with some autoimmune disorders. Many cancers in their early stages do not even show any symptoms, which prevents timely and effective treatment. There are also complex disorders that present highly varied symptoms that can lead doctors in the wrong direction, at least at first. Not surprisingly, there is an immense interest in molecular‐level diagnostics that promise to deliver far more accurate and rapid diagnoses without relying on interpreting symptoms. While this can raise new challenges, such as poor‐quality samples or analyzing complex data sets, molecular diagnostics has made progress across a range of clinical conditions, including infectious diseases and some cancers, through identification of characteristic molecular markers. A wide variety of diseases could also be diagnosed using next‐generation sequencing (NGS), including solid cancers or rare diseases of genetic origin. NGS …