Myopia as a latent phenotype of a pleiotropic gene positively selected for facilitating neurocognitive development, and the effects of environmental factors in its expression

Screening of genes interacting with high myopia and neuropsychiatric disorders

Clinical studies have demonstrated an association between high myopia (HM) and neuropsychiatric disorders; however, the underlying mechanism of the association is not clear. We used whole exome sequencing (WES) in combination with the Genetic Variants Classification Criteria and Guidelines published by the American College of Medical Genetics (ACMG) and bioinformatics analysis to clarify the interrelationship between candidate genes. Causative genes for ocular diseases (45.38%) followed by neuropsychiatric disorders (22.69%) accounted for the highest proportion of genes that exhibited high pathogenicity in HM patients were found. Four pathogenic gene mutations were identified according to ACMG guidelines: c.164_165insACAGCA and c.C1760T in POLG, c.G1291A in COL5A1, and c.G10242T in ZNF469. Three causative genes for neuropsychiatric diseases, PTPRN2, PCDH15 and CDH23, were found to fall at the HM locus. The above results suggest that these genes may interact in high myopia and neuropsychiatric diseases.

Effect of Age and Refractive Error on Local and Global Visual Perception in Chinese Children and Adolescents

PURPOSE

This study investigated the impact of age and myopia on visual form perception among Chinese school-age children.

METHODS

This cross-sectional study included 1,074 students with a mean age of 12.1 ± 4.7 (range = 7.3-18.9) years. The mean spherical equivalence refraction (SER) of the participants was -1.45 ± 2.07 D. All participants underwent distance visual acuity (VA), refraction measurement and local and global visual form perception test including orientation, parallelism, collinearity, holes and color discrimination tasks.

RESULTS

The reaction times of emmetropes were slower than those of myopic and high myopic groups on both local (orientation, parallelism, and collinearity) and global discrimination tasks (all p < 0.05). A reduction in reaction times was found with increasing age on both local and global discrimination tasks (all p < 0.05). Age was significantly associated with both local and global visual perception performance after adjusting for gender, visual acuity and SER (orientation, β = -0.54, p < 0.001; parallelism, β = -0.365, p < 0.001; collinearity, β = -0.28, p < 0.001; holes, β = -0.319, p < 0.001; color, β = -0.346, p < 0.001).

CONCLUSIONS

This study revealed that both local and global visual perception improve with age among Chinese children and that myopes seem to have better visual perception than emmetropes.

Association of Myopia with cognitive function among one million adolescents

BACKGROUND

Myopia is a leading cause of visual impairment worldwide, and its increasing incidence is of public health concern. Cognitive function was associated with myopia among children, but evidence for adolescents is scarce. The purpose of this study was to determine whether myopia is associated with cognitive function, and which cognitive ability, verbal or non-verbal, is involved.

METHODS

We conducted a population-based cross-sectional study of 1,022,425 Israeli candidates for military service aged 16.5-18 years. Participants underwent a comprehensive battery of tests assessing verbal and non-verbal intelligence, which yields a summarized cognitive function score (CFS). In addition, subjective visual acuity examination followed by objective non-cycloplegic refraction was carried out for each participant. Association between myopia and cognitive function was evaluated by multivariable logistic regression models adjusted for gender, age, country of origin, socioeconomic status, years of education, body mass index, height and year of examination.

RESULTS

Compared to the intermediate CFS of the entire cohort, participants who had the highest CFS had 1.85-fold (95% CI, 1.81 to 1.89; P < .001) higher odds of having myopia and 2.73-fold (95% CI, 2.58 to 2.88; P < .001) higher odds of high myopia, while participants with the lowest CFS had 0.59-fold (95% CI, 0.57 to 0.61, P < .001) lower odds of having myopia. The verbal components of the cognitive function assessment had stronger associations with myopia than the non-verbal components (P < .001, for all).

CONCLUSIONS

Cognitive function, especially verbal intelligence, is strongly and consistently associated with myopia among adolescents.

Shape analysis of spatial relationships between orbito-ocular and endocranial structures in modern humans and fossil hominids

The orbits and eyes of modern humans are situated directly below the frontal lobes and anterior to the temporal lobes. Contiguity between these orbital and cerebral elements could generate spatial constraints, and potentially lead to deformation of the eye and reduced visual acuity during development. In this shape analysis we evaluate whether and to what extent covariation exists between ocular morphology and the size and spatial position of the frontal and temporal areas in adult modern humans. Magnetic resonance imaging (MRI) was used to investigate patterns of variation among the brain and eyes, while computed tomography (CT) was used to compare cranial morphology in this anatomical region among modern humans, extinct hominids and chimpanzees. Seventeen landmarks and semi-landmarks that capture the outline of the eye, frontal lobe, anterior fossa/orbital roof and the position of the temporal tips were sampled using lateral scout views in two dimensions, after projection of the average grayscale values of each hemisphere, with midsagittal and parasagittal elements overlapped onto the same plane. MRI results demonstrated that eye position in adult humans varies most with regard to its horizontal distance from the temporal lobes and, secondly, in its vertical distance from the frontal lobes. Size was mainly found to covary with the distance between the eye and temporal lobes. Proximity to these cerebral lobes may generate spatial constraints, as some ocular deformation was observed. Considering the CT analysis, modern humans vary most with regard to the orientation of the orbits, while interspecific variation is mainly associated with separation between the orbits and endocranial elements. These findings suggest that size and position of the frontal and temporal lobes can affect eye and orbit morphology, though potential effects on eye shape require further study. In particular, possible effects of these spatial and allometric relationships on the eye and vision should be examined using ontogenetic samples, vision parameters such as refractive error in diopters, and three-dimensional approaches that include measures of extraocular soft tissues within the orbit.

Phenotypic and genotypic correlation between myopia and intelligence

Myopia, or near-sightedness, is our most common eye condition and the prevalence is increasing globally. Visual impairment will occur if uncorrected, whilst high myopia causes sight-threatening complications. Myopia is associated with higher intelligence. As both are heritable, we set out to examine whether there is a genetic correlation between myopia and intelligence in over 1,500 subjects (aged 14-18 years) from a twin birth cohort. The phenotypic correlation between refractive error and intelligence was -0.116 (p < 0.01) - the inverse correlation due to the fact that myopia is a negative refractive error. Bivariate twin modeling confirmed both traits were heritable (refractive error 85%, intelligence 47%) and the genetic correlation was -0.143 (95% CI -0.013 to -0.273). Of the small phenotypic correlation the majority (78%) was explained by genetic factors. Polygenic risk scores were constructed based on common genetic variants identified in previous genome-wide association studies of refractive error and intelligence. Genetic variants for intelligence and refractive error explain some of the reciprocal variance, suggesting genetic pleiotropy; in the best-fit model the polygenic score for intelligence explained 0.99% (p = 0.008) of refractive error variance. These novel findings indicate shared genetic factors contribute significantly to the covariance between myopia and intelligence.

Analysis of the volumetric relationship among human ocular, orbital and fronto-occipital cortical morphology

Recent research on the visual system has focused on investigating the relationship among eye (ocular), orbital, and visual cortical anatomy in humans. This issue is relevant in evolutionary and medical fields. In terms of evolution, only in modern humans and Neandertals are the orbits positioned beneath the frontal lobes, with consequent structural constraints. In terms of medicine, such constraints can be associated with minor deformation of the eye, vision defects, and patterns of integration among these features, and in association with the frontal lobes, are important to consider in reconstructive surgery. Further study is therefore necessary to establish how these variables are related, and to what extent ocular size is associated with orbital and cerebral cortical volumes. Relationships among these anatomical components were investigated using magnetic resonance images from a large sample of 83 individuals, which also included each subject's body height, age, sex, and uncorrected visual acuity score. Occipital and frontal gyri volumes were calculated using two different cortical parcellation tools in order to provide a better understanding of how the eye and orbit vary in relation to visual cortical gyri, and frontal cortical gyri which are not directly related to visual processing. Results indicated that ocular and orbital volumes were weakly correlated, and that eye volume explains only a small proportion of the variance in orbital volume. Ocular and orbital volumes were also found to be equally and, in most cases, more highly correlated with five frontal lobe gyri than with occipital lobe gyri associated with V1, V2, and V3 of the visual cortex. Additionally, after accounting for age and sex variation, the relationship between ocular and total visual cortical volume was no longer statistically significant, but remained significantly related to total frontal lobe volume. The relationship between orbital and visual cortical volumes remained significant for a number of occipital lobe gyri even after accounting for these cofactors, but was again found to be more highly correlated with the frontal cortex than with the occipital cortex. These results indicate that eye volume explains only a small amount of variation in orbital and visual cortical volume, and that the eye and orbit are generally more structurally associated with the frontal lobes than they are functionally associated with the visual cortex of the occipital lobes. Results also demonstrate that these components of the visual system are highly complex and influenced by a multitude of factors in humans.

A novel review of the evidence linking myopia and high intelligence

The association between myopia and high intelligence has been the subject of much vexed debate in academic circles, particularly over the last two decades. This debate has risen from the observation that, over recent centuries, the prevalence of myopia amongst most populations has coincided with a marked increase in the average level of intelligence in these populations. The relationship between myopia and intelligence and theories surrounding this association is examined by the authors. Additionally, the various factors that confound the myopia and high intelligence debate, such as genetics, educational levels, ethnicity, and environmental factors were also explored by the authors. Whilst most studies found a positive correlation reaching statistical significance between myopia and high intelligence compared to emmetropes and hyperopes, further research is required to determine whether this association is causal.

Genetic variation of the RASGRF1 regulatory region affects human hippocampus-dependent memory

The guanine nucleotide exchange factor RASGRF1 is an important regulator of intracellular signaling and neural plasticity in the brain. RASGRF1-deficient mice exhibit a complex phenotype with learning deficits and ocular abnormalities. Also in humans, a genome-wide association study has identified the single nucleotide polymorphism (SNP) rs8027411 in the putative transcription regulatory region of RASGRF1 as a risk variant of myopia. Here we aimed to assess whether, in line with the RASGRF1 knockout mouse phenotype, rs8027411 might also be associated with human memory function. We performed computer-based neuropsychological learning experiments in two independent cohorts of young, healthy participants. Tests included the Verbal Learning and Memory Test (VLMT) and the logical memory section of the Wechsler Memory Scale (WMS). Two sub-cohorts additionally participated in functional magnetic resonance imaging (fMRI) studies of hippocampus function. 119 participants performed a novelty encoding task that had previously been shown to engage the hippocampus, and 63 subjects participated in a reward-related memory encoding study. RASGRF1 rs8027411 genotype was indeed associated with memory performance in an allele dosage-dependent manner, with carriers of the T allele (i.e., the myopia risk allele) showing better memory performance in the early encoding phase of the VLMT and in the recall phase of the WMS logical memory section. In fMRI, T allele carriers exhibited increased hippocampal activation during presentation of novel images and during encoding of pictures associated with monetary reward. Taken together, our results provide evidence for a role of the RASGRF1 gene locus in hippocampus-dependent memory and, along with the previous association with myopia, point toward pleitropic effects of RASGRF1 genetic variations on complex neural function in humans.

Functional craniology and brain evolution: from paleontology to biomedicine

Anatomical systems are organized through a network of structural and functional relationships among their elements. This network of relationships is the result of evolution, it represents the actual target of selection, and it generates the set of rules orienting and constraining the morphogenetic processes. Understanding the relationship among cranial and cerebral components is necessary to investigate the factors that have influenced and characterized our neuroanatomy, and possible drawbacks associated with the evolution of large brains. The study of the spatial relationships between skull and brain in the human genus has direct relevance in cranial surgery. Geometrical modeling can provide functional perspectives in evolution and brain physiology, like in simulations to investigate metabolic heat production and dissipation in the endocranial form. Analysis of the evolutionary constraints between facial and neural blocks can provide new information on visual impairment. The study of brain form variation in fossil humans can supply a different perspective for interpreting the processes behind neurodegeneration and Alzheimer’s disease. Following these examples, it is apparent that paleontology and biomedicine can exchange relevant information and contribute at the same time to the development of robust evolutionary hypotheses on brain evolution, while offering more comprehensive biological perspectives with regard to the interpretation of pathological processes.

Genospirituality: genetic engineering for spiritual and religious enhancement

The most frequently discussed role for genetic engineering is in relation to medicine, and a second area which provokes discussion is the use of genetic engineering as an enhancement technology. But one neglected area is the potential use of genetic engineering to increase human spiritual and religious experience - or genospirituality. If technologies are devised which can conveniently and safely engineer genes causal of spiritual and religious behaviours, then people may become able to choose their degree of religiosity or spiritual sensitivity. For instance, it may become possible to increase the likelihood of direct religious experience - i.e. 'revelation': the subjective experience of communication from the deity. Or, people may be able to engineer 'animistic' thinking, a mode of cognition in which the significant features of the world - such as large animals, trees, distinctive landscape features - are regarded as sentient and intentional beings; so that the individual experiences a personal relationship with the world. Another potentially popular spiritual ability would probably be shamanism; in which states of altered consciousness (e.g. trances, delirium or dreams) are induced and the shaman may undergo the experience of transformations, 'soul journeys' and contact with a spirit realm. Ideally, shamanistic consciousness could be modulated such that trances were self-induced only when wanted and when it was safe and convenient; and then switched-off again completely when full alertness and concentration are necessary. It seems likely that there will be trade-offs for increased spirituality; such as people becoming less 'driven' to seek status and monetary rewards - as a result of being more spiritually fulfilled people might work less hard and take more leisure. On the other hand, it is also possible that highly moral, altruistic, peaceable and principled behaviours might become more prevalent; and the energy and joyousness of the best churches might spread and be strengthened. Overall, genospirituality would probably be used by people who were unable to have the kind of spiritual or religious experiences which they wanted (or perhaps even needed) in order to lead the kind of life to which they aspired.

A book of ideas collected from Medical Hypotheses: Death can be cured by Roger Dobson

A new collection of ideas from Medical Hypotheses by Roger Dobson is entitled Death can be cured and 99 other Medical Hypotheses. It consists of humorous summaries of Medical Hypotheses articles from the past 30 years. The book's humour derives mainly from the subject matter, although sometimes also from the 'unconventional' approach of the authors with respect to matters such as evidence, argument or inference. Medical Hypotheses has generated such a lot of apparently- or actually-bizarre ideas because it aims to be open to potentially revolutionary science. The journal's official stance is that more harm is done by a failure to publish one idea that might have been true, than by publishing a dozen ideas that turn out to be false. Bizarre ideas tend to catch attention, and may stimulate a valuable response--even when a paper is mostly-wrong. A paper may be flawed but still contain the germ of an idea that can be elaborated and developed. The journal review process is susceptible to both false positives and false negatives. False positives occur when we publish an idea that is wrong; false negatives occur when we fail to publish an important idea that is right, and a potential scientific breakthrough never happens. False positives are more obvious, since the paper will be ignored, refuted, or fail to be replicated--and often attracts criticism and controversy. Editors may therefore take the more cautious path of avoiding false positives more assiduously than false negatives; however, this policy progressively favours less-ambitious science. Consequently, in Medical Hypotheses the 'set point' of risk is nearer to the false positive end of the spectrum than for most journals - and the publication of many apparently-bizarre papers is a natural consequence of this policy.