Poly-Y Male Syndrome

Poly-Y Male Syndrome

Poly-Y Male Syndrome

What is a Poly Y Syndrome?

XYYY Syndrome is a chromosome that affects men and boys only. It is also known as Triple Y or 48, XYYY Syndrome. It is extremely rare and there is little information, partly because men and boys with XYYY Syndrome have developed or have not been diagnosed with major difficulties.

From the information that is available, it seems that most boys and men with this condition do not have major birth defects or major handicaps and their long term outlook is fairly good. However, many men and boys who have been diagnosed with XYYY syndrome do experience behaviour, educational and medical problems.

Poly-Y Male Syndrome

Background of the study

The information in this brochure is partly derived from the medical literature published. Since a first boy was diagnosed in 1965, however, only nine people have been described in the medical literature.

They have been diagnosed because they received something unusual and are therefore likely to represent people more severely affected and unlikely to represent an average boy and man group with XYYY.

If so few people with a specific chromosome condition have been described, it is not always possible to be sure whether certain features are caused or not. Some young men may develop XYYY syndrome normally or with minimal problems and never come to the attention of the physician’s profession.

This is thought to be true for as many as 85% of young men who have a single additional Y chromosome with XYY syndrome. This leaflet is also available on the database of Unique. During childhood, all 8 members of Unique were diagnosed, aged between 11 and 24, three with mosaicism.

This means that they too are unlikely to represent an average group for XYYY. Their information, however, helps to give the most complete picture of XYYY available today. Four families completed a detailed questionnaire about their son’s development in 2005.

Can boys ever live independently?

Most boys take care of their personal needs from a reasonably early age. Toilet training appears to be only slightly delayed and daily activities such as dressing, eating and hygiene are reasonably well managed. However, in Unique’s experience, the typical behaviour difficulties mean that boys and young men need regular supervision, so that independence may be limited. Poly-Y Male Syndrome

Unique’s members may not be typical of all XYYY men, and it is clear from the medical literature that
some XYYY men can live independently and marry (Hori 1988).

Causes

Rearrangements occur in chromosomes as part of evolution. They affect children from all parts of the world and from all types of background. They also happen naturally in plants and animals. So there is no reason to suggest that your lifestyle or anything that you did would make XYYY syndrome or any other sex chromosome variation more likely.

XYYY syndrome arises from the fertilisation of a woman’s egg with a sperm containing an atypical number of Y chromosomes. Normal male sperm contains either one X or one Y chromosome, and in XYYY syndrome the sperm contains two or three Y chromosomes. Sperm containing additional Y chromosomes can arise in a number of ways. Usually, it is due to a series of mistakes in sperm
development were copies of the Y chromosome fail to separate from each other. This is called nondisjunction. Another possibility is that the father has additional Y chromosomes as well, either having XYY chromosomes in all of his cells (XYY syndrome) or in just some of his cells that give rise to the sperm.

Sperm containing two Y chromosomes are found in over one per cent of samples from normal adult male sperm donors, so they are fairly common. The father himself usually has normal chromosomes but a mistake has occurred when his sperm were forming. When YY sperm are involved in XYYY syndrome, the third Y chromosome is most likely to result from a mistake in the very earliest days
when the embryo is developing after conception (when the baby is made).

Typically when the mistake happens after conception, mosaicism is the result, so there may be cells with a single Y, no Y’s, two Ys or four Ys as well.

What first signs were there?

The first signs of XYYY are most likely to be developmental delays, particularly in language development. ‘It would’ve been prematurely backward, he hasn’t smiled much, slept little and his speech didn’t develop as he grew older.’ recalled one family.

Is it different during pregnancy?

Pregnancy with an XYYY baby is not shown to be abnormal. Three out of four unique babies were born one month earlier (Sele, 1975; U) after their due date and one boy described in the medical literature.

Poly-Y Male Syndrome

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