Genetic studies of two bi-parental populations derived from crossing parents with rapid and slow rates of deterioration showed that the deterioration rate is a heritable trait (broad spectrum heritability, H2 of 0.56 0.87).
Autism is highly heritable, with monozygotic concordance rates ranging from 36%to91%1% and overall autism spectrum heritability rates estimated to be as high as 90% [ 12- 15].
Despite significant heritability of autism spectrum disorders (ASDs), their extreme genetic heterogeneity has proven challenging for gene discovery.
The large differential between twin and molecular estimates of heritability for autism spectrum disorders, for which a large contribution of rare genetic variants is likely, suggests that this might be the case [ 4].
It is clear that patients with positive response to lithium treatment can be separated into a subgroup based on symptoms as well as an increased level of genetic heritability of bipolar-spectrum disorders along first-degree family lines.
Since twin studies tend not to include twins separated and placed in radically different environments—say, contemporary Manhattan versus San Bushmen, or 19th century versus contemporary Dutchmen they often overstate the heritability of traits relative to the full spectrum of human societies, and correspondingly understate the role of environment.
The heritability of neurodevelopmental disorders including ASDs (autism spectrum disorders) suggests a strong genetic component to these diseases and a number of contributing genes have been identified (Persico and Bourgeron, 2006; Abrahams and Geschwind, 2008).
Prepulse inhibition (PPI) of the startle reflex has been suggested as a candidate endophenotype for schizophrenia research, as it shows high heritability and has been found deficient in schizophrenia spectrum disorders.
The broad clinical spectrum of migraine and the results from heritability studies have posted a challenge to the understanding of the underlying pathophysiology and molecular genetics.
Therefore, we only exemplified the partitioning spectrum of EW36 due to its highest heritability.
Bipolar and genetically related spectrum disorders such as unipolar affective disorders have a heritability of 89% with environmental effects limited to the specific or unique environment with no evidence for effects from the shared family environment [McGuffin et al., 2003].
