A to Z of syndromes

A-Z syndromes: Klinefelter syndrome

How to recognise and support children who have this rare neurological condition

Klinefelter syndrome, affecting males, is a collection of characteristics that occurs as a result of two or more X chromosomes. The syndrome was named after Harry Klinefelter, an American endocrinologist, and is common – occurring in all races. It is thought that one male in every 500 live births is affected and the incidence is rising. However, this may be due to increasing awareness, reflective of the sophistication of the methods to diagnose. 

Picture: Alamy

Although a chromosomal abnormality it is not inherited and usually occurs as a random mutation, with advancing maternal age being thought to increase the risk slightly. This condition is a result of non-disjunction during meiosis, this is when the sex chromosomes fail to separate in the ovum or the sperm. The ovum, once fertilised, carries additional X sex chromosomes, as well as the father’s Y sex chromosome which codes for a male infant.


There is a trajectory of severity. The symptoms can be so subtle that the parents/carers and the healthcare professionals may not realise the child is affected. While those more severely affected usually have three or more X chromosomes and the symptoms occur mainly because of limited testosterone affecting the secondary sexual characteristics. There may be overt signs of this and males may be born with undescended testicles, small penis and hypospadias.  

The child may be slightly slower than average in developing, delayed in reaching their milestones and have difficulties with reading and communicating effectively. Although if a child is aware that they are different this may affect their confidence and the parents/carers may report that the child is quiet and passive. They may be investigated for muscle weakness, poor coordination, delayed puberty, gynaecomastia or a female fat deposition. Physiotherapy and encouraging sport can improve muscle function and, if there are speech and language difficulties, support in developing the individual’s communication skills and cognitive behavioural therapy can be used to address this and any conduct issues.   

Boys who are pre-puberty do not differ much from their peers and, should this be diagnosed, the priority would be to normalise and not medicalise them.

As the age of puberty approaches males who wish to look more masculine can take a testosterone supplement and surgical intervention for gynaecomastia and gonads can be augmented. In adulthood the main concern will be limited fertility or sterility.

Case study

Ahmed was the first boy born to a British Asian family who had several sisters. When he was born the midwife and the family noticed that his urethra did not reach the tip of his penis. He had surgery when he was nearly one which was complicated because he had been circumcised, so a small skin graft was also needed.

Ahmed was a healthy child and unlike his parents he was tall, but this did not cause concern. His family did not have much contact with the health services and he had an uneventful early childhood. His teachers identified that he was behind his peers in reading. It was not until he was 14 that Ahmed and his parents began to get nervous about his development as he was increasingly tall for his age, but had not begun puberty. They consulted the GP who referred him to a specialist. The endocrinologist performed blood tests and low levels of testosterone were identified. Chromosome analysis identified an additional X chromosome and a diagnosis of Klinefelter syndrome was made.

Ahmed and his family were offered counselling and a treatment plan was made to provide Ahmed with the testosterone he lacked. This was offered not only to build up Ahmed’s muscle mass and develop more masculine characteristics, but also to improve his bone density and reduce the risk of osteoporosis. 

Further information

Doreen Crawford is nurse adviser with the consultancy Crawford McKenzie and Annette Dearmun is divisional head of nursing and clinical governance, Oxford University Hospitals NHS Trust.

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