Phenotype Signs And Symptoms Of Klinefelters Syndrome Biology Essay


Klinefelters syndrome is a common chromosomal disorder affecting around one in every 500 male babies, Cover, 2006; Better Health Channel, 2008. It can also be referred to as 47XXY, XXY or XXY syndrome, as it entails a male that has inherited an extra X chromosome. This disorder also increases the risk of other diseases that can usually affect both males and females. Behaviour and learning skills can also be affected as the various typical features of an affected male can be both physical and mental. Although Klinefelter's syndrome cannot be prevented, there are different management techniques and therapies that can assist in maintaining a regular lifestyle.

Phenotype; signs and symptoms:

Unless a small penis, hypospadias, hypotonia or undescended testicles have been found as indications, it is difficult to diagnose 47XXY (Cover, 2006; Better Health Channel, 2008; Saladin, 2007). Furthermore, Cover (2006) described that "a condition known as torticolis, in which the baby's head and neck are slightly twisted to one side, may be present" (p.66). Thus, some affected babies might be much easier to identify than others. Better Health Channel also indicates physical features present in adolescents include; slim appearance, longer arms and legs, fewer amounts of hair and hypogonadism (2008).

Cognitive development:

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Delay of cognitive development such as speech delay and low concentration is often seen in Klinefelter syndrome (Cover, 2006; Better Health Channel, 2008). Moreover, Cover mentioned that children with the syndrome tend to avoid eye contact and have difficulties with learning, speaking and concentration, as well as poor communication skills (2006). Despite having the disorder, some children could enter higher education or university (Cover, 2006). Although children with the syndrome have some disadvantages in cognitive development in childhood, it is possible to improve their skills though their growth.


Because of the extra X chromosome, fertility rates are very low; or some people with the syndrome are not able to produce testosterone (Better Health Channel, 2008).

Genotype: how the disorder is transmitted:

Klinefelter Syndrome is an irregularity in the number of chromosomes that affects about in 500 males (Better Health Channel, 2008) or 0.1-0.2% of the general population, regardless of race (Lanfranco, Kamischke, Zitzmann & Nieschlag, 2004). People typically have two sex chromosomes in each cell: females have two X chromosomes (46, XX), and male have one X and one Y chromosome (46, XY). In most men one of these X chromosomes is inherited from their mother and a Y from their father, however men with Klinefelter Syndrome generally have an extra X chromosome, although there are variants (Visootsak, Aylstock & Graham, 2001), resulting in 47 chromosomes, 3 of which are sex chromosomes (XXY).. Variants include 48, XXXY, 48, XXYY, 49, XXXXY and mosaicism (46,XY/47,XXY) and these account for 20% of cases (Baer, Block, Eberl, Farrell, Mahoney & Sait, 2005; Lanfranco et al., 2004). Klinefelter syndrome is not inherited; it usually occurs as a random event during the formation of reproductive cells. An error in cell division called nondisjunction results in reproductive cells with an abnormal number of chromosomes (Lee, Cheng, Ahmed, Shaw & Hughes, 2007). For example, an egg or sperm cell may gain one or more extra copies of the X chromosome as a result of nondisjunction if one of these atypical reproductive cells contributes to the genetic make up of a child, the child will have one or more extra X chromosomes in each of the body's cells (Yung Seng et al., 2007).

How the disorder is diagnosed:

Klinefelter syndrome is diagnosed using a number of tests, such as a physical examination. This involves a rectal exam of the prostate gland, as the majority of males with Klinefelter syndrome have an enlarged prostate (Better Health Channel, 2008). Chromosome analysis is a means of proving the diagnosis, and other assessments include blood tests (which verifies hormone levels) and semen examination, which tests fertility, as most males with Klinefelter syndrome won't have the ability to have children (Better Health Channel, 2008). Klinefelter syndrome also can be detected before birth (prenatally) through amniocentesis or chronic villus sampling, however it is estimated that only 10% of boys are diagnosed using amniocentesis (Visootsak, et al., 2001). However, this is not routinely done; it is usually diagnosed in childhood, during puberty or in adulthood by medical history; physical exam and the chromosome test (called a karyotype).

Mortality of the disease:

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Adult male with Klinefelter Syndrome have an increased risk of developing breast cancer and a chronic inflammatory disease called systemic lupus erythematosus, which can threaten the life of the person (Visootsak et al., 2001). Klinefelter syndrome is associated with an increased risk of certain diseases and conditions, such as diabetes mellitus, infertility, leukaemia, non-Hodgkin's Lymphoma and varicose veins (Lanfranco et al., 2004).


As Klinefelter Syndrome occurs at some point during the meiotic division, there is no way to prevent it, however increased maternal age has been linked to a higher risk of XXY syndrome (Visootsak et al., 2001).

Common therapies of the disorder:

As there is no cure for Klinefelter Syndrome, there are a number of treatments available which help with the various effects of having the condition. This might require having cosmetic surgery for the removal of large breast tissue or counselling for the person to help him manage his condition (Better Health Channel, 2008). An effective lifelong treatment is testosterone therapy, which develops the normal changes that occur in puberty and improves fatigue and libido (Amory, Anawalt, Paulsen & Bremner, 2000) however it does not effect gynecomastia or fertility (development of breast tissue) (Lanfranco et al., 2004). It also helps with bone mineral density, strength, masculinity and body hair (Lanfranco et al., 2004) Parents must also sometimes employ educational support and speech therapy, as the IQ of a boy with 48, XXXY syndrome is typically somewhere between 40-60, with significant delay in speech and motor abilities (Visootsak et al., 2001). Reproductive technologies can be implemented in order to aid the man to have kids, for example IVF, due to their generally very low sperm count and regular screening tests should also be put into service so as to allow for early diagnosis of particularly at risk issues, such as breast cancer (Better Health Channel, 2008).

Long-term prognosis:

Although Klinefelter's Syndrome itself does not kill the person, or even shorten the lifespan (Visootsak et al., 2001), it is associated with a number of other problems. Men with Klinefelter Syndrome are at an increased risk of several problems, most of them however are not life-threatening. Common in people with Klinefelter syndrome are several autoimmune disorders, including systematic lupus erythematosus (SLE), rheumatoid arthritis and Sjogren syndrome (Visootsak et al., 2001). There is a danger of hypothyroidism among men with Klinefelter's and 25% of males with the syndrome have decreased bone density (or osteoporosis) (Visootsak et al., 2001), with most also having reduced muscle strength, due to an androgen deficiency (Lanfranco et al., 2004). Deep-vein thrombosis, hypostatic ulceration and pulmonary embolism are also a threat in men with the syndrome (Visootsak et al., 2001) as are venous stasis ulcers and thromboembolic disease, which affect as much as a third of patients (Lanfranco et al., 2004). Males with Klinefelter's Syndrome also tend to have considerable medical, psychological or social problems (Lanfranco et al., 2004) and there is also a greater frequency of diabetes mellitus, low glucose tolerance and obesity, as well as a higher chance of death from diabetes (Lanfranco et al., 2004). Equally worrying is that they are 20 times more likely to get breast cancer than normal men, but still less likely than females (Amory et al., 2000; Visootsak et al., 2001). A minor issue in men with Klinefelter's is that they are less likely to have normal beard growth, with only 1 in 5 experiencing it, however more significant is after 25 years of age approximately 70% will experience a loss of libido and potency (Lanfranco et al., 2004) Although the risks are useful to know, the great majority of men with the condition don't know they have Klinefelter's (Harley, Sawalha & Scofield, 2009) with two-thirds of cases not being diagnosed (Lanfranco et al., 2004).


There has been quite a lot of research into Klinefelter's Syndrome, and it started in 1940 with three men named Fuller Albright, Edward Reifenstein and Harry Klinefelter (Amory et al., 2000). It was then first described in 1942 as an endocrine disorder and the XXY karyotype was established in 1959 (Lanfranco et al., 2004)

With new technology there are some new discoveries, one of these is the fact that some spermatozoa in men with Klinefelter's Syndrome have been found to have extra X chromosomes (Amory et al., 2000). Therefore for those men with the syndrome that have sperm and wish to have kids, selection of the sperm to be used in reproductive technologies must be very careful, so as to reduce the likelihood of transmitting the condition (Amory et al, 2000). There has also been research into the genital anomalies among men with Klinefelter's, and this illustrated that they are not commonly seen, but there is still an association (Lee et al., 2007).

Typical age of onset of signs and symptoms:

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Klinefelter syndrome is not usually diagnosed at birth, as the male baby looks healthy and normal, however there are certain signs that can indicate they have been affected by the condition which include a small penis, undescended testicles and their urethra is located on the underside of the penis rather than the tip. The syndrome is usually diagnosed during puberty when the expected physical changes in normal males cease to occur. At this stage the affected male will still have a small penis, small testicles, lack of facial and pubic hair, taller than average height, enlarged breasts, slim physique and disproportionately long legs in comparison to the rest of their body, possible speech and hearing difficulties and a slightly impaired IQ. (Better Health Channel, 2008). Aside from the physical signs which lead to the diagnosis of the syndrome there are numerous tests used which include blood tests to check for hormone levels, semen examination to check fertility as most males affected by the condition are infertile due to the extra X chromosome, a physical examination including a rectal exam to feel for an enlarged prostate which is common amongst those with Klinefelters and a chromosome analysis to confirm the diagnosis.

Ways in which the disorder affects ability to interact with society:

Males affected by Klinefelter's have varying factors that detrimentally influence their interaction amongst society. Intelligence, language and speech difficulties often affect males once they begin their academic education where it becomes noticeable that they are not progressing at the same rate as their normal peers. Most males with the condition have a lag in language skills with a mildly delayed expression of single words. Studies have shown that comprehension and receptive skills are not affected as highly as expressive language. (Visootsak & Graham, 2006) There are conflicting studies on the behaviour and personalities of those with Klinefelters, however most are described to be reserved and often lacks confidence. One study concluded that 47XXY males are timid and immature with difficulty relating to cohort whilst another study apposes suggesting that they relate well with other people and are friendly, kind and helpful. Despite the conflicts in some studies, it is commonly accepted that 47XXY males have an increased likelihood of anxiety and depression and are more prone to substance abuse in adolescents(Bender, Harmon & Linden, 1995). A factor that may be considered most detrimental is the impaired sexual function of affected males. Although it has been found that some pregnancies have occurred without medical assistance, it is very unlikely for a male with Klinefelters to be fertile. As stated earlier, during puberty their penis does not grow as normal males would during this time so they are left with a noticeably smaller penis.

Special requirements needed:

Despite the management of this condition, there are limited other requirements they might need throughout their life. They are still mentally capable of caring for themselves and partaking in common daily activities so a personal or carer that may be necessary for other genetic conditions is not necessary in most cases.