Red flags

KS/XXY is a spectrum condition. The severity and frequency of effects vary widely.

Small, firm testes are by far and away the most common of these.

This is why we ask medical professionals to ‘Lift the fig leaf’ to check the size of the testes to help identify the 1 in 600 males who have KS/XXY. 

Early diagnosis can change lives. Please be aware of these red flags. Klinefelter’s Syndrome isn’t rare – but it is rarely diagnosed. Help us to change this.

Red flags for adults and teens

This is the most consistent symptom of KS/XXY

Libido low or absent due to lack of testosterone production.

Those affected rarely have to shave. Feminised pattern of pubic hair. However, may have excess hair on arms and legs due to stimulation of FSH

Occurs in around 25% of cases.  Usually caused by some degree of breast tissue, but can be compounded by excess fat.

Hips are often wider than is usual. Feminine distribution of fat.  Torso comparatively short compared to body length. Hands inclined to be small.

Testosterone levels are usually low or very low. However young men may produce normal levels but these will decrease.

Most adults with KS/XXY are infertile

Can affect internal muscles causing constipation, difficulty swallowing. Lack of upper body strength, 'shambling' gait. Flat feet.

Ligaments very elastic.  Can cause clicking joints, dislocations, pain in joints and muscles, fatigue, constipation, IBS

Due to lack of testosterone.

Many will have problems with executive function which affects the ability to organise, initiate, plan,  control emotions etc. Affects memory.

Adults can look decades younger than their true age. Act younger than age, can be very vulnerable.

Many have difficulty processing information and interpreting social cues. Makes it difficult for them to make and maintain relationships

KS/XXY often live alone or with parents/siblings.

Not all KS/XXY adults are particularly tall but most are taller than would be expected when compared to other members of their family.

Research suggests that depression and extreme anxiety are more common than would be expected. An increased risk of schizophrenia and paranoia is also reported.

Although there is little research in this area, anecdotal evidence suggests that gender identity seem to be relatively common.

Many KS/XXYs appear to be on the autistic spectrum but there is little research to support this.

Image of a fig leaf displayed vertically

Red flags for children

Many have difficulty processing information and interpreting social cues. Makes it difficult for them to make and maintain relationships

Undescended  testicle(s) are common. Usually doctors will recommend a small operation to avoid the risk of them becoming cancerous.

Some boys may have a smaller than average penis.

Penis and testes may be smaller than is usual.

KS/XXY babies are sometimes identified as 'floppy babies'.  Their muscle tone may be poor, causing excessive flexibility of the joints. This can delay physical development - sitting up, walking.  Can cause clumsiness. The internal muscles can also be affected causing difficulty sucking, swallowing and constipation.  Physiotherapy may help. Encourage your child to be active. This will help to strengthen muscles.

Ligaments very elastic.  Can cause clicking joints, dislocations, pain in joints and muscles, fatigue, constipation, IBS

Although IQ is usually in the normal range, KS/XXY youngsters often have a noticeable difficulty learning. Difficulty processing information particularly verbal.

Have difficulty understanding social cues, following a conversation, making and maintaining relationships with peers.

Many will have problems with executive function which affects the ability to organise, initiate, plan,  control emotions etc. Affects memory.

KS/XXY children are often less mature than their peers. Can be very vulnerable.

Not all KS/XXY adults are particularly tall but most are taller than would be expected when compared to other members of their family.

Youngsters are often tall and skinny with little muscle or tall but overweight with a feminine fat distribution.

Many KS/XXYs appear to be on the autistic spectrum but there is little research to support this.