The Extent Genes Affect Behavior In Turner Syndrome

Introduction

Genetics as a phenomenon was discovered in the late 19th century. This can be considered as quite a late discovery in comparison to other medical advancements such as general anesthesia which can be seen throughout recorded history in each culture. Genetic conditions like the well-known downs syndrome or Huntington’s disease are due to faulty genetics at play, causing the person to sometimes have characteristic facial features or intellectual disabilities.

A gene is a sequence of DNA bases that code for either a polypeptide chain or functional RNA; they can even exist in different forms called alleles this is how organisms have variations within species like different eye color or blood type. Genes that have random mutations, can alter the primary level of DNA through the error. There are two types of error: substitution and deletion. Substitution is when one base is substituted with another; deletion is when one base is deleted. Often these errors cause no effect on the organism due to the degenerate non-overlapping nature of the genetic code but sometimes they do and thus cause genetic disorders. The disorder I will investigate through the course of this report is Turner syndrome.

Through my work experience at clinical genetics, I have learnt that it can be quite visually clear when a person has a specific genetic condition due to characteristic feature, for example, a short palpebral fissure indistinct philtrum and micrognathia all indicate to the person having foetal alcohol syndrome or FAS. These specific characteristics for specific genetic conditions are especially useful for clinical geneticists who help identify genetic causing conditions. However, for some genetic disorders, genetic doctors are faced with no outward physical disabilities but a difference in other factors like puberty and sexual development behavior fertility or even employment and education; these are all clinical features geneticist take into account when diagnosing. I will be specifically looking at the behavioral factors affected by the mutated gene that causes Turner syndrome. This disorder can then have behavioral characteristics associated with it. Thus I want to see whether these behavior problems are due to the mutated gene or other ‘nature/nurture’ triggers. I also want to investigate the extent genes affect behavior in the mentioned genetic disorder.

Turner syndrome

Turner syndromes features were described in 1938 and 1959 by turner and he found that the cause of this syndrome is an absent X chromosome 45 X karyotype in the 23rd chromosome pair. This mutation only happens in girls/ women and affects one in twenty-five thousand live female births. Girls who have this condition do not have the second sex chromosome. Statistics from the Oxford Desk Reference: clinical genetics and genomics second edition show us that ‘80% of the x chromosome in 45 x is of maternal origin’ meaning the origin of the mutation is thought to be because of paternal meiotic error that then causes genetic abnormal sex chromosomes. For this condition, there is help available through NHS approved groups that help the person themselves and those around the family and friends that are affected. An example of this help is the service of NCARDRS (National Congenital Anomaly and Rare Diseases Registration Service) that helps scientists find a way to prevent this disease from occurring and also find better ways to treat patients that currently have Turner Syndrome. As there is no cure for this syndrome, a prevention or healthcare scheme is highly useful for the patient and other affected.

The distinguishable characteristics of Turner Syndrome are the girls are shorter than average and have underdeveloped sexual organs (ovaries) that then cause irregular to most likely non-existent monthly periods and thus infertility. Due to the circumstances of these specific conditions, girls may not be diagnosed until the stage of puberty or until they don’t show ‘sexual development associated with puberty.’ There are other characteristics associated with Turner’s syndrome but they vary for each individual. For example, cardiovascular malformations can be found in 15-50% of women with Turner Syndrome. As mentioned before, there is no cure for this genetic disorder like many other genetic disorders. The only thing doctors can do is treat and minimalize associated symptoms. For example, the girls have their heart, kidney and reproductive system regularly checked for abnormalities. In addition, life expectancy is unfortunately slightly reduced but with good access to healthcare, the above regular health checks and effective treatment to problems in the early stage, life expectancy can be increased.

Clinical Features – Behavior

It is acknowledged that the mutation in the gene that consequently causes the deletion of an X chromosome in the 23rd pair then causes behavioral problems associated with Turner Syndrome. Therefore, we can safely say that here, for this disorder, genes do cause behavioral changes. For Tuners Syndrome, studies were conducted to see whether there was a link between behavior and the genetic disorder thus implying genes do have an impact on behavior. By looking at a medical journal, a study called McCauley et al. (2001) indicated final results of when compared to a control group, girls who have Turner Syndrome faced challenges with ‘social relationships’ and ‘school progress’. Most of the girls who have this disorder seem to face social adjustment problem such as being unable to make as many friends in comparison to a control group. This could be because of physical features that make them stand out and therefore different to other pupils; this would then cause, in an enclosed environment like a school or workplace, bullying and other negative actions to possibly occur. Another behavioral attribute that has been associated with Turner Syndrome is the girls having subtle perceptual difficulties such as finding it hard to read faces or facial affect recognition. From the above study conducted in 2001, girls that had Turner Syndrome had fewer friends and with these minimal friends, spent less time with them in general, in comparison to a control group. Overall, the study concluded that the girls were socially backwards and in a new social group, seemed distressed, not confident and felt highly vulnerable.

Another study was conducted in 1997 called Skuse et al to investigate girls that have Turner Syndrome. The study was conducted to see the differences from a woman that had a deprived maternal (from the mother) X chromosome and a woman with a deprived paternal (from the father) chromosome. The studies concluded that women without an X chromosome from the mother were ‘significantly better adjusted, with superior spoken language and sophisticated functional skills that mediate social interaction’ when compared to women without an X chromosome in the 23rd pair from the father. When there is an X chromosome from the father, the girl will do better in a social situation than if the child only has her one X chromosome from the mother. This study here clearly indicates a link between a human’s genetic code and their social cognition. In regards to employment capability and Turner Syndrome, a US study that was organized with a sample size of two hundred and forty women with Turner Syndrome, found that the women had qualifications at high levels and were in employment. This was independent of the parental origin of the X chromosome: there is no link between where there the X chromosome is derived from and intelligence. Most women were independent and lived well in their adult lives.

Conclusion

In conclusion, we see that genes do in fact affect certain areas of behavior in the genetic disorder of Turner Syndrome. The mutation in the genetic code that results in the 2nd X chromosome in the 23rd pair to be missing in girls, affects areas within the idea of behavior, but through research, I have realized it predominately affects social behavior. The girls and women affected can be socially backwards in the sense of finding it hard to form strong social relationships like close friendships and overall ‘socially awkward.’ This lack of ‘correct’ behavior is initially a result of genetics and the genetic condition but an increase in this behavior may have been fuelled by environmental factors later on. However, when researching other areas of behavior like communication skills or emotional behaviors like empathy or anger didn’t seem to be affected by the condition. Here, we see that for Turner syndrome, genes do not affect this area. However, studies like the ones mentioned, show a clear link between genes and behavior in Turner Syndrome especially between genes and social behavior.