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Sexual Development

Sexual development in PWS is affected by the diminished or disrupted production of sex hormones. This condition is called hypogonadism (failure of the gonads to function properly – testes in men and ovaries in women.) In PWS, hypogonadism is present from birth and is thought to be caused by a combination of hypothalamic and primary gonadal deficiencies.

Hypogonadism in PWS is characterised by underdeveloped genitalia, incomplete puberty and infertility. The affects on genitalia are evident from birth, in both boys and girls. Cryptorchidism (undescended testes) is typical in the vast majority of male infants and a procedure called orchidopexy to bring testes down may be necessary.

Puberty and Fertility

Puberty is usually delayed and/or incomplete, with slow or disrupted progression. On average, children with PWS reach a stage called pubarche earlier than is typical, but premature adrenarche (or pubarche) can happen before the ages of 8 or 9 in 14-30% of children with PWS, although this is not related to actual pubertal onset. Adrenarche is a separate process to puberty which typically occurs a few years before and causes new hair growth, body odour, skin and mood changes.

The onset of puberty may begin as expected or be delayed. Early pubertal development is often experienced normally with some breast development in girls and a degree of penile development in boys. However, the penis and testes rarely reach full development and menstruation in girls either does not start, is sporadic, or is very delayed, sometimes starting much later in adulthood. Some girls develop oligomenorrhea (infrequent menstrual periods) which is usually only intermittent spotting, but primary amenorrhea (absent menstruation) is slightly more common. A very small number of children with PWS are affected by precocious (early) puberty which can result in having a slightly advanced bone age. Treatment to suppress development may not be needed as pubertal advancement is usually not sustained.

Fertility

It was previously thought not possible for men or women with PWS to have children. There are no known cases of a man with PWS fathering a child, but there have been a handful of women with PWS who have had a baby. Without sex hormone treatment, fertility is unlikely, but current advice is that birth control should be considered for women with PWS who are sexually developed, even if menstruation is sparse and minimal. Similarly, males should also be counselled about the possibility of their own fertility if penile length and testicular volume is normal. Infertility in males is complex and it remains unknown if it is possible to correct. Multiple forms of hypogonadism have been observed involving testicular dysfunction and various hormone deficiencies. If fertile, those with PWS by deletion have a 50% chance of their baby being born with either Angelman syndrome if they are female, or PWS if they are male. Those with PWS by UPD would have every chance of having a healthy baby.

Sex Hormone Treatment

Testosterone therapy for boys and oestrogen therapy for girls can be used for promoting and maintaining pubertal development. They are sometimes prescribed to induce puberty, but are often used when puberty stalls. These therapies may improve sexual function and have the potential to bring about fertility in females (and possibly males.) However, some research suggests that attempts to normalise male genitalia with gonadtropins and androgens might be more effective during infancy or early childhood.

Sex hormone therapies are also beneficial for bone health, retaining muscle mass and for general well being. Due to hormone deficiencies, adults with PWS have low bone mineral density, but sex hormone therapy can increase bone density and help prevent osteoporosis, particularly if given during the period of bone building (before age 25-30 yrs.)

Key Points for Providing Support

  • Puberty is usually delayed and incomplete. The person with PWS will be aware of their developmental differences and this needs to be handled sensitively.
  • Sex hormone treatments should be considered to help normalise pubertal development and improve sexual function.
  • Inidividuals with PWS have the same needs and desires as everyone else and want to have relationships.
  • Sex education needs to explicitly teach responsibilities, boundaries, appropriateness and safety because it cannot be assumed these are understood.
  • Long term relationships can be successful with appropriate support.
  • Female fertility is possible, particularly with sex hormone treatment. Male fertility is unlikely, but fertility outcome with sex hormone treatment is uncertain. Birth control should be considered.

Relationships

Individuals with PWS appear to have a normal sex drive and want to have relationships in the same way as their peers. They will dream of having a partner, getting married and having a baby, so it is advisable to help them understand and accept the limitations of sexual development in PWS ahead of time so that it is not a shock and cause of stress later on.

The social and emotional deficits of PWS can lead to a somewhat naive approach to relationships. Individuals with PWS are often very open about their wants and desires, can form stereotyped ideas and may lack understanding of relationship appropriateness. It is important that sex education for people with PWS includes clear information about responsibilities, limits and boundaries, what is OK behaviour, and saying no. People who have intellectual disabilities are also known to be more vulnerable to sexual abuse and therefore need ongoing, additional guidance on keeping themselves safe.

Relationships can be difficult to sustain due to social skill and behavioural challenges, but long lasting relationships can be achieved with sufficient support. For example, support may be required in facilitating problem solving due to difficulties in understanding the feelings of others and expressing their own. Relationships can be successful and some people with PWS have been known to become engaged and marry.

Additional Resources