Klinefelter's syndrome

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Klinefelter's syndrome
Classification & external resources
ICD-10 Q98.0-Q98.4
ICD-9 758.7
DiseasesDB 7189
eMedicine ped/1252 
MeSH D007713

Klinefelter's syndrome, 47,XXY or XXY syndrome is a condition caused by a chromosome aneuploidy. Affected males have an extra X sex chromosome. The principal effect is abnormal testicular development and reduced fertility. A variety of other physical and behavioral differences and problems are common, though severity varies and many boys and men with the condition have little detectable effect. It is the second-most common extra chromosome condition, and is named after Dr. Harry Klinefelter, an endocrinologist at Massachusetts General Hospital, Boston, Massachusetts, who first described it in 1942.[1] The condition exists in roughly 1 out of every 500 to 1,000 males.[2]

Contents

[edit] Signs and symptoms

Affected males are almost always effectively sterile, although advanced reproductive assistance is sometimes possible[3] and some degree of language learning impairment may be present.[4] In adults, possible characteristics vary widely and include little to no signs of affectedness, a lanky, youthful build and facial appearance, or a rounded body type with some degree of gynecomastia (increased breast tissue).[5] Gynecomastia to some extent is present in about a third of individuals affected, a slightly higher percentage than in the normal XY population, but only about 10% of XXY males' gynecomastia is noticeable enough to require surgery.[6]

The more severe end of the spectrum of symptom expression is also associated with an increased risk of breast cancer,[7] pulmonary disease, varicose veins, diabetes mellitus, rheumatoid arthritis, and osteoporosis, risks shared to varying degrees with females.[8]

Because of how genetics is currently understood, it is thought that rare X-linked recessive problems occur even more infrequently in XXY males than in normal XY males, since these conditions are transmitted by genes on the X chromosome, and people with two X chromosomes are typically carriers rather than affected.[citation needed]

Patients will be found to have a low serum testosterone level but a high serum follicle-stimulating hormone (FSH) and luteinizing hormone (LH).[citation needed]

There are many variances within the XXY population, just as in the most common 46,XY population. While it is possible to characterise 47,XXY males with certain body types, that in itself should not be the method of identification as to whether someone has 47,XXY or not. The only reliable method of identification is karyotype testing.

[edit] Cause

The extra X chromosome is retained because of a nondisjunction during germ cell division. The XXY chromosome arrangement is one of the most common genetic variations from the XY karyotype, occurring in about 1 in 500 to 1,000 live male births.[2] Because of the extra chromosome, individuals with the condition are usually referred to as "XXY Males", or "47,XXY Males".[citation needed]

In mammals with more than one X chromosome, the genes on all but one X chromosome are not expressed. This happens in XXY males as well as normal XX females.[citation needed] A few genes, however, have corresponding genes on the Y chromosome and are capable of being expressed. These triploid genes in XXY males may be responsible for symptoms associated with Klinefelter's syndrome.[citation needed]

The first published report of a man with a 47,XXY karyotype was by Patricia A. Jacobs and Dr. J.A. Strong at Western General Hospital in Edinburgh, Scotland in 1959.[9] This karyotype was found in a 24-year-old man who had signs of Klinefelter's syndrome. Dr. Jacobs described her discovery of this first reported human or mammalian chromosome aneuploidy in her 1981 William Allan Memorial Award address.[10]

[edit] Treatment

The genetic variation is irreversible,[citation needed] but its symptoms can be altered or treated in a number of ways, including testosterone treatment and other therapies.[citation needed]

While the gender identity of people with the XXY karyotype is generally stable,[citation needed] it seems people with Klinefelter's suffer from gender identity disorder more often than people without it.[citation needed] However, this observation is based on the reports of support groups for transgender and transsexual people; no scientific study on this subject has been done.[citation needed] The fact that a person undergoing treatment for gender identity disorder has Klinefelter's syndrome is often missed, or the patient is not told, although in many jurisdictions this additional diagnosis can have legal consequences, for example regarding name change or medical treatment having to be taken.[citation needed]

Inadequately treated hypogonadism in Klinefelter syndrome increases recognized psychosocial morbidity.[11] At least one study indicates that planned and timed support should be provided for young men with Klinefelter syndrome, to ameliorate current poor psychosocial outcomes.[11]

Alternatives to testosterone treatment include a daily regime of cardiovascular exercise along with a complete soy diet or regular vitamins / herbs.[citation needed] Weight bearing exercise creates muscles.[12]

[edit] Variations

The 48, XXYY (male) syndrome occurs 1 in 17,000 births and has traditionally been considered to be a variation of Klinefelter's syndrome. XXYY is no longer generally considered a variation of KS, although it has not yet been assigned an ICD-9 code.

Males with Klinefelter syndrome may have a mosaic 47,XXY/46,XY constitutional karyotype and varying degrees of spermatogenic failure. Mosaicism 47,XXY/46,XX with clinical features suggestive of Klinefelter syndrome is very rare. Thus far, only about 10 cases have been described in literature.[13]

[edit] References

  1. ^ Klinefelter, HF Jr; EC Jr Reifenstein & Albright (1942), "Syndrome characterized by gynecomastia, aspermatogenesis without a-Leydigism and increased excretion of follicle-stimulating hormone.", J Clin Endocrinol Metab 2: 615-624, PMID: too early to be indexed. Klinefelter, HF (1986), "Klinefelter's syndrome: historical background and development.", South Med J 79 (9): 1089-1093, PMID: 3529433 talks about the history of the development of the literature.
  2. ^ a b Klinefelter Syndrome (HTML). Health Information. National Institute of Health and Human Development (2007-02-19). Retrieved on 2007-03-24. and Klinefelter syndrome (HTML). Genetics Home Reference. National Library of Medicine (2006). Retrieved on 2007-03-24. both provide statistical estimates.
  3. ^ Denschlag, Dominik, MD; Tempfer, MD Clemens & Myriam, MD Kunze et al. (October 2004), "Assisted reproductive techniques in patients with Klinefelter syndrome: A critical review", Fertility and Sterility 82 (4): 775-779, DOI:10.1016/j.fertnstert.2003.09.085 describes assisted reproduction techniques for Klinefelter patients.
  4. ^ Graham, JM Jr; AS Bashir & RE Stark et al. (June 1988), "Oral and written language abilities of XXY boys: implications for anticipatory guidance.", Pediatrics 81 (6): 795-806, PMID: 3368277
  5. ^ Abstract of Klinefelter, HF (1986), "Klinefelter's syndrome: historical background and development.", South Med J 79 (9): 1089-1093, PMID: 3529433 provides information on microorchidism (small testes), hypogonadism (infertility/sterility and androgen hormone function) and gynecomastia. Bock, Robert (1993 Aug). Understanding Klinefelter Syndrome: A Guide for XXY Males and Their Families (HTML). NIH Pub. No. 93-3202. Office of Research Reporting, NICHD. Retrieved on 2007-03-28. offers substantive information about body type and appearance until a more rigorous source is found/supplied.
  6. ^ Bock, Robert (1993 Aug). Understanding Klinefelter Syndrome: A Guide for XXY Males and Their Families, Adolescence section (HTML). NIH Pub. No. 93-3202. Office of Research Reporting, NICHD. Retrieved on 2007-03-29. describes statistical occurrence of gynecomastia and surgical treatment.
  7. ^ Hultborn, R; C Hanson & I Kopf et al. (1997 Nov-Dec), "Prevalence of Klinefelter's syndrome in male breast cancer patients.", Anticancer Res. 17 (6D): 4293-4297, PMID: 9494523
  8. ^ For instance, while Hultborn, R; C Hanson & I Kopf et al. (1997 Nov-Dec), "Prevalence of Klinefelter's syndrome in male breast cancer patients.", Anticancer Res. 17 (6D): 4293-4297, PMID: 9494523 shows a 50-fold increased risk of developing breast cancer versus normal males, study of the SEER Cancer Statistics Review (CSR) databases available at the National Cancer Institute reveal that female relative risk of breast cancer incidence compared to normal males is around a 100 to 200-fold increase, which indicates XXY males may not be as much at risk statistically as normal females are.
  9. ^ Jacobs PA, Strong JA. "A case of human intersexuality having a possible XXY sex-determining mechanism". Nature 1959 Jan 31;183(4657):302-3. PMID 13632697
  10. ^ Jacobs PA. "The William Allan Memorial Award address: human population cytogenetics: the first twenty-five years". Am J Hum Genet. 1982 Sep;34(5):689-98. PMID 6751075
  11. ^ a b Simm PJ, Zacharin MR. "The psychosocial impact of Klinefelter syndrome--a 10 year review". J Pediatr Endocrinol Metab 2006 Apr;19(4):499-505. PMID 16759035
  12. ^ Ivan's Research - http://www.xxytalk.com - This reference is not adquately formatted or referenced
  13. ^ Velissariou V, Christopoulou S, Karadimas C, Pihos I, Kanaka-Gantenbein C, Kapranos N, Kallipolitis G, Hatzaki A. "Rare XXY/XX mosaicism in a phenotypic male with Klinefelter syndrome: case report". Eur J Med Genet 2006 July - August;49(4):331-337. PMID 16829354

[edit] See also

[edit] External links

v • d • e
Pathology: chromosome abnormalities (Q90-Q99)

Autosomal trisomies: Down syndrome, Edwards syndrome, Patau syndrome, Trisomy 9, Warkany syndrome 2

Autosomal monosomies/deletions: Wolf-Hirschhorn syndrome, Cri du chat, Angelman syndrome/Prader-Willi Syndrome

X/Y linked: Turner syndrome, Triple X syndrome, Klinefelter's syndrome, XYY syndrome

Translocations: Philadelphia chromosome, Burkitt's lymphoma

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