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Pre-Implantation Genetic Diagnosis: An innovative technique with exciting potential

Mr. Paul Serhal. MRCOG
Medical Director
Hon. Consultant/Senior Lecturer

PGD is a very early method of prenatal diagnosis for those couples who are at risk of transmitting an inherited disease to their children. For such couples to produce a healthy family, the main option open to them is for the woman to become pregnant and undergo prenatal diagnostic test, such as amniocentesis or chorionic villus sampling (CVS) at between 12-16 weeks of her pregnancy.
If the foetus is found to be affected, the couple have to decide if they wish to continue with the pregnancy. Using PGD we perform the diagnostic test before implantation, thus avoiding the need for recurrent termination of pregnancies.
For PGD the couple undergo routine IVF procedures and when the embryos are between 6-10 cells (3 days after the egg collection) 1-2 cells can be removed (embryo biopsy) and used for the diagnosis. Unaffected embryos can be transferred back to the woman so that pregnancy is started knowing that the foetus will be unaffected with the familial disease.
The Human genetics and Embryology Group at UCL, under the direction of Mr. Paul Serhal, has been performing the diagnosis of sex for patients carrying X-linked disease (which will only affect male children) since 1991 and in 1195 were the first group to perform PGD for patients carrying chromosome abnormalities.
UCL Centre for PGD will undertake PGD for embryo sexing to avoid X-linked disease (such as Duchenne muscular dystrophy and haemophilia), for the detection of chromosome abnormalities (such as translocations and gonadal mosaicism) and the diagnosis of severe single gene defects (such as cystic fibrosis, b-thalassaemia and sickle cell anaemia).
The UCL group is one of the leaders in this field, analysing chromosomes using a procedure called fluorescent in-situ hybridisation (FISH).

Analysis of Oocytes

The work on oocyte chromosomes shows that abnormalities originating from oocytes account for a large proportion of spontaneous miscarriages. It is already known that the chance of producing a chromosomally abnormal foetus increases with age, an effect called 'age-related aneuploidy'. Therefore, women over 35 years of age are offered a prenatal diagnostic test to ensure their pregnancy is chromosomally normal.

Analysis of Sperm

Examining chromosomes from sperm samples is problematic as the chromosomes are tightly packed within the sperm head. Using the FISH technique, the sperm nuclei have first to be de-condensed so that the probes can gain access to the chromosomes.

Analysis of Embryos

The examination of the chromosomes of human embryos is a major interest of the Human genetics and Embryology Group and a research team is currently involved in the investigation of early human development through such examinations. The results emerging from this work may also have important consequences for IVF and PGD.

The embryos being analysed come from several groups of patients: those with repeated IVF failure, repeated miscarriage, those showing abnormal oocyte or embryo development and patients undergoing PGD.
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Hair Loss In Women
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Normally we shed an average of 100 hairs each day which are then replaced. If, however, they are not replaced or the daily shedding is higher than normal then true hair loss (alopecia) occurs. In women there are a number of conditions that cause diffuse hair loss. The commonest of these is inherited female pattern hair loss or androgenetic alopecia which occurs in up to 30% of women below the age of 55. As with men the susceptibility to balding in women is acquired from one or both parents; however, the baldness is not as severe and is confined to thinning on the top and crown.The hair loss is triggered by the small amount of male hormone that women possess. After the menopause more women are seen with hair loss because the levels of female hormones decrease. Another type of hair loss in women is caused by trauma such as tightly braiding the hair, using hair dressing chemicals, accidents or burns. Cosmetic surgery especially after face lifts can cause hair loss above and in front of the ears because of traction. Chemicals used in hair dressing can cause breakage of the hairs, which is not true hair loss. However, if the substances are used incorrectly they can cause damage to the skin and to the hair roots so causing permanent damage.

Severe illness, surgery, rapid weight loss, emotional stress, and medical conditions such as thyroid disease or low blood count can cause or accelerate hair loss. Once the stress is removed or treated hair usually grows back within a few months. After pregnancy many women experience 'thinning' of their hair. This is because the hormones in pregnant women delay the normal shedding so in fact the hair is thicker before a women gives birth.
Localised skin problems such as eczema, psoriasis, and infections can cause temporary or permanent hair loss

There are many drugs known to cause hair loss as a side effect. Some of these include certain contraceptive pills, blood thinning drugs, thyroid medications, and chemotherapy for cancer. The effects are reversible once the drug is stopped or changed.

Alopecia Areata is a form of hair loss in which there are circular patches of baldness. It is thought that antibodies that attack the hair root cells cause Alopecia Areata. In more severe forms there is total loss of all the hair on the head. Sometimes medical treatment is successful in treating the less severe forms of this condition and sometimes the hair loss clears up on its own but it may recur at a later time.

A woman who is experiencing thinning hair should first contact their GP who will take a detailed medical history. Depending on what he/she thinks is a possible cause you may have to undergo some blood tests or be referred to a dermatologist who is a specialist in skin conditions. Treatment then depends on the cause found.

In clinics collaborating with Doctorinternet, the majority of women suffer from genetic hair loss which is the commonest cause for balding. Some women are prescribed medical treatment with minoxidil, which is a lotion that is applied twice a day to the thinning areas of the scalp. Others are suitable for hair transplantation, which involves taking hairs from the thicker area and surgically transplanting them into the thinning zones. The Clinic can do this because certain areas of the scalp around the back and sides are not programmed to become thin. Often more than one operation is needed in order to create enough density in the balding areas. This transplanted hair should then be permanent.

There are other causes for hair loss that can also be treated with surgery. Scars from accidents or burns can be treated either by cutting out the damaged area (scalp reduction) or by transplanting small grafts of hair bearing skin into the area. Hairlines in those who have had facelifts or damage from hot rollers or chemicals can be reconstructed using grafts containing one to three hairs each.
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Infertility / Groundbreaking research

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Researchers in London are working to help overcome some of the major infertility problems suffered by women.

Consultant Sammy Lee and his colleagues in the fertility unit, Great Portland Street, London have been testing a new procedure which helps embryos to hatch through the zona pellucida and have a greater chance of implantation.
Once fertilised the egg begins to divide. These divisions all take place within the confines of the zona pellucida. Before the embryo can implant in the lining of the womb, the zona pellucida has to give way to allow the embryonic cells to come out of their casing and attach to the endometrial cells.
There is a tendency for zona pellucida to harden within the passages of time and the actual processs of IVF may exacerbate their process. Indeed premature hardening of the zona pellucida may be a cause of infertility!. The process of hatching occurs naturally in all clinical pregnancies and there may be advantage in weakening the zona pellucida using micromanipulation techniques with older patients or patients who have persistently expierienced the failure of treatment with IVF- as in these instances the important research has proved so valuable.
The technique takes only a matter of minutes to complete and involves micromanipulation of the zona pellucida to enable the embryos to hatch and implant.
Already 11 mothers have given births that were treated in this way and others are ongoing. This represents an amazing 21% success rate.
The fertility unit is delighted with the results achieved so far and looks forward to being able to help even more women who may not otherwise have been able to complete a successful pregnancy.
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