7 months of research: a personal review

This blog entry is a translation of „Über 8000 Zugriffe: Zeit für ein Resumee“.

I started researching XXY in April 2014 and began this blog on 8th May 2014. The most surprising facts have been the following:

XXY is not necessarily Klinefelter’s syndrome

Klinefelter’s syndrome describes possible effects of testosterone deficit. In addition to that, a certain number of people with additional X chromosome are not suited for testosterone replacement therapy (TRT) because they have normal testosterone values, they are happy with their body or they do not even identify as males. The only communality is the additional X chromosome. Moreover it should be emphasized that XXY people are more than just a syndrome (as the term „Klinefelter males“ suggests), they have strengths.

Emotional distress is not exclusively connected to testosterone deficit and infertility

Different polls and studies revealed the association between depressions and testosterone deficit is rather indirectly given. TRT improves energy, endurance and general well-being with most (not all) XXY but serious effects may arise from communication difficulties like identification of facial expressions (e.g. sad versus angry) and interpreting tone of the voice (prosody). Misunderstandings and difficulties to maintain relationship with others often result. Research also showed that the ability to put oneself in the other’s shoes („theory of mind“) is also impaired but mainly „for the moment“ as processing time is delayed in XXY. Impaired impulse control and executive functions (consequences of actions, processing new information, sudden changes) add to the daily challenges of many XXY.

Many XXY have sensory gating disorder

Polls in XXY forums and groups, personal communication and my own experience, as well as at least one research study suggest enhanced prevalence for sensory gating disorder in XXY, in a wider sense called as sensory processing disorder encompassing sense of balance as well as motoric skills. The most affected sense seem to be hearing (oversensitivity to noise) and vision (sensitivty to flickering and bright light) but occasionally touch and smell are also reported.

Psychiatric diagnoses like ADHD and autism have higher prevalence in XXY

Commonly, a large number of unknown XXY cases is assumed to be present and it is difficult to estimate the overall number of co-morbid ADHD, autism and further psychiatric conditions. Depending on studies (mostly with relatively small numbers of participants and lacking statistical evidence), 60-80 % of XXY have additional ADHD, with about 50 % inattentive subtype (quiet, not hyperactive but often distracted). In 30-50 %, autism spectrum disorder (ASD) is diagnosed – with all subtypes like PDD-NOS (e.g. 30 % in the Netherlands), Asperger’s syndrome as well as high functional autism – which gives further evidence that intelligence in XXY is not lower but even higher than average.

There is a study about stigmatization of children with ADHD through labels which reveals that parents are mostly concerned about the symptomes but the diagnose itself barely enhances the stigma. The possibility to benefit from therapeutical support and services compensates this fear.

According to DSM-V and latest research (see e.g. Temple Grandin, The autistic brain), sensory gating disorder, avoiding eye contact and executive dysfunctions are core symptomes of autism. It might be assumed that the majority of XXY therefore shows autistic-like symptomes and traits and are rather on the autistic spectrum than on the neurotypical spectrum (feel free to test yourself here).

Conflicting information about the use of testosterone injections versus transdermal (gel) applications

Current state for me has been the statement that viable sperm is mostly available during puberty and adolesence but this ability will be increasingly lost between 20 and 30. US studies show viable sperm even in adulthood which partly depends on the application before. Injections result in too rapid increasing testosterone values killing remnant sperms while gel application provides lower but constant doses. In USA, aromatase inhibitors are used together with TRT. Aromatase is an enzyme converting testosterone into estrogen (called aromatization). Increasing estrogen increases the risk of gynecomastia and breast tumors. Moreover, inhibited conversion increases endogenous testosterone production helping to maintain fertility with XXY. So far, aromatase inhibitors are used with off-label indication, though, and possible side effects do not seem well studied. Injections show another disadvantage as sudden rise and subsequent decline might favour mood swings (instead of fighting them).

Lack of longitudinal studes in all areas of XXY

Considering possible effects of testosterone deficit in XXY, like diabetes, osteoporosis, poor muscle mass as well as social behavior and general well-being, statistic significant long-term studies are missing so far. Most studies refer to cross-sections (at a certain point of time) but with inhomogenous treatment. The only long-term study has not been controlled by placebos.  Most indications for improvements by TRT refer to men with normal chromosome type (46,XY). Anecdotal evidence is also given for XXY males with respect to libido, energy, endurance and attention.

Negative feedback can be mostly deduced to incompetent medical treatment (lacking knowledge of the physician) as XXY specials are rather seldom worldwide. The few XXY specialists have only few XXY patients and might underestimate the degree of the XXY spectrum. Inappropiate treatment also occurres with XXY who do not identify as males.

Intersexuality might be but has not to be present

Leading associations and support groups often ignore this taboo: In contrast to XY, XXY humans rather have a female body composition and tend to be emotionally more sensitive than XY males. Intersexuality might be present anatomically but also males who do not idenfity as males.  They all belong to the XXY spectrum and discussion about intersexuality should not be excluded in support groups and organisations.

Both genes and hormones serve as cause for XXY traits

A large number of genes is situated on the X chromosome influencing the neural brain development. The second X chromosome with remaining active genes enhances the number of active X chromosome genes in general (so-called gene dosage effect). Further genes have been identified to affect the physical phenotype of XXY.

Regarding testosterone deficit, there are barely any measurements of prenatal testosterone values. Anecdotal evidence exists for testosterone deficit during mini puberty (small penis and missing genitals) in the first three months after birth, as well as during puberty and later in adulthood. Evidence for testosterone deficit in fetus might be given by measuring the 2D:4D ratio of finger lengths. It correlates with the relation of estradiol to testosterone during fetus stage. A more reliable estimations originates from measuring the ano-scrotal distance. Studies show conflicting results, though. 


Independent of temporal occurrence of testosterone deficit, the second X chromosome is always present and researchers still do not know which genes are still active and responsible for the diversity of the XXY spectrum, e.g. XXY showing strong testosterone deficits and weak deficits, showing strong and weak autistic traits, some having gynecomastia and dyslexia and others not.

Both genes and hormones contribute to the brain development and brain differences have also been found in XXY.

Certain strengths and talents seem to be more prevalent in XXY

XXY pay more attentation to details, tend to think in pictures or patterns, and are often creative people. Deficits in communication and social interaction with peers might result in strengths like attending to special interests and becoming experts in their fields. XXY are mathematicians, graphic designers, photographers, artists and musicians as well as engineers. Apart from their profession, XXY are often said to be more sensitive, having a great sense for social injustice, honesty (to the degree of bluntness), long-term memory as well as love to animals.


XXY is a genetic variation adding another facet of diversity to XX and XY. XXY often comes along with sensory processing disorders affecting one or more senses. Sensory gating disorder also allows for a sharpened glance to details and is possibly responsible for improved long-term memory skills anchoring the information. As a result, XXY may accumulate large amounts of knowledge in their area of interest (too much incoming information needs large memory storage).

Only few of us will be able to reproduce, to forward genes but – in the context of advocates for abortion and prenatal gene tests – we still have a right to live! Parents will never decide FOR their kids whether they want to have kids later, neither with XX nor with XY. Having kids will be the private matter of the kid. Some XXY decide for donor sperm or adoption. Nature always finds a way raising children – even if it’s not the own child.

My hope and engagement for the future:

I wish an open-minded and frank discussion within the XXY spectrum but also between XXY and practising physicians. Scientific evidence is given that XXY is much more than what is told by many local support groups and testosterone treatment appears to be more complex than suggested by specialists. In some countries like the Netherlands, specialists already work together successfully, i.e., researchers, psychiatrists, psychologists, endocrinologists and urologists and neurologists. XXY is more than just replacing a hormone deficit. Its certainly not a one-size-fits-all condition. We need individual treatment! Confidence in the treatment is very important and sometimes the sole sheet anchor for XXY who have to deal with difficulties at so many levels. The most important thing for me is, however, being appreciated for my strengths and talents. Comprehension and accomodation make it easier to overcome the difficulties in communication and interaction.