The low cost of the latest ‘Next Generation Sequencing’ (NGS) technologies means that they are now accessible to researchers and clinicians in both developed and developing countries. Today, thousands of whole human genomes have been sequenced, notably in the context of the 1000 Genomes Project, and soon sequencing an individual genome will be as commonplace as analyzing blood or urine samples, for example.
The challenge now lies in efficiently exploiting the massive amount of genome information (and other kinds of high throughput data), to understand the effects of genetic variations/mutations and to predict future health risks for the individual.
The relationships between an individual genotype (an organism's full hereditary information) and his phenotype (an organism's observed properties, such as morphology, development, or behavior) are clearly complex. The genetic information encoded in the genome sequence contains the blueprint for the potential development and activity of an organism, but the implementation of this information depends on the functions of the gene products (nucleic acids and proteins). These molecules do not act in isolation, but form complex, dynamic networks involving genes, proteins and metabolites, in the context of the cell, the tissue and the organism.
Although the genotype largely determines the phenotype of an individual, environmental factors also play a part. Even two organisms with identical genotypes normally differ in their phenotypes, for example monozygous (i.e. identical) twins share the same genotype, but they never have the same phenotype, although their phenotypes may be very similar.
Both the genotype and the phenotype of an individual are dynamic. The phenotype clearly changes during the lifetime of an individual and is determined by hereditary factors, but also by nutrition, lifestyle and other environmental factors. But, the genotype can also be modified during an individual's lifetime by mutations, epigenetics, or even gene therapies.