What is a behavioural phenotype?
Much of learning disability is the result of genetic disorder, transmitted by variation in the pattern of genetic material (the genotype) carried as a chain of chemical codes, the genes, along lengthy coiled strings of DNA, the chromosomes. The result is a set of observable characteristics (the phenotype); the outcome of the interactive combination of the physical (somatic) and psychological components that make a person (Figure 1). Figure I Genotype and phenotype View larger version of this figure in a new window PHENOTYPE – The somatic phenotype This includes: • the bodily habitus which is the physical equivalent of personality; the physical appearance the dysmorphology which allows syndromes such • as Down’s and Fragile X to be identified from a photograph; • any associated medical conditions including abnormalities of organs such as the eyes, heart, bowel or limbs; • abnormalities of physiology (e.g. epilepsy) or chemistry (e.g. the toxic over-production of phenylalanine in Phenyik
