TEMPORARY COMMITTEE ON HUMAN GENETICS
AND OTHER NEW TECHNOLOGIES OF MODERN MEDECINE
HEARING on 27 March 2001
Professor Joep GERAEDTS
Prof. Dr. Joep Geraedts
PO Box 1475
6201 BL Maastricht
Professor Joep P.M. Geraedts (1948) studied general biology at the Catholic University of
Nijmegen. In 1975 he obtained a PhD from the University of Leiden with his thesis:
'Constitutive heterochromatin as a marker for chromosomal studies in human somatic cells and
From 1972-1982 he held posts as a scientist at the Institute of Human Genetics at Leiden
In October 1982 he was appointed full professor of genetics and cell biology at the University of
In January 1983 he became the first director of the Clinical Genetics Centre serving South-East
Netherlands. He has also started the centre for preimplantation genetic diagnosis in Maastricht,
which is still the only PGD-centre in the Netherlands.
He has served as chairman of the Dutch Society of Human Genetics and is currently chairman of
the Society of Dutch Clinical Genetics Centres.
At the European level he is actively involved in the European Society of Human Reproduction
and Embryology, in particular as coordinator of the Special Interest Group on Reproductive
Genetics and steering member of the so-called ESHRE PGD Consortium.
PREIMPLANTATION GENETIC DIAGNOSIS IN EUROPE
Preimplantation Genetic Diagnosis (PGD) is an alternative to prenatal diagnosis for the detection
of monogenic and chromosomal disorders. After IVF or ICSI one or two blastomeres are
biopsied from about 8-cell preimplantation embryos and tested using PCR or FISH. Unaffected
embryos are selected for transfer to the uterus, preventing termination of pregnancy after
prenatal diagnosis. Legislation, regulation and service of PGD varies among European countries.
In 1997, the ESHRE (European Society of Human Reproduction and Embryology) PGD
Consortium was formed as part of the ESHRE Special Interest Group on Reproductive Genetics,
in order to undertake a long-term study of the efficacy and clinical outcome of PGD. In
December 1999, the first PGD Consortium report was published discussing referrals on 323
couples, 392 PGD cycles and 82 pregnancies. In the second data collection round, contributing
centres were asked to send in data from their PGD activities before this date, as well as from 1
October 1998 until 1 May 2000, in order to have as complete a review as possible of PGD
practices in these centres. The cumulative data consist of 886 referrals and 1319 PGD cycles.
Many couples have had affected children and have objections to (more) terminations of
pregnancy. The pregnancy rate is less than 20 %. This figure is below expectancy and results
from the increased maternal age and limited number of embryos available for transfer. The rate
of multiple pregnancies is high. There is no indication that the children born show more
abnormalities other than from multiple pregnancies. The most serious problem is misdiagnosis.
Although not all of these data are encouraging, the practice of PGD is becoming more and more
established and more and more different applications are emerging.
Most couples having a child or a family member with a hereditary disease and having an
increased risk themselves, in the recent past have had the following alternatives to decrease the
risk: (1) to refrain from having children and eventually opt for adoption, (2) to accept the risk,
(3) to opt for donor insemination or IVF using donor oocytes, or (4) to undergo prenatal
diagnosis with or without selective abortion. Preimplantation genetic diagnosis (PGD) is an
alternative option especially with regard to prenatal diagnosis.
PGD takes place between fertilisation and implantation, but in most cases on the third day of
early embryonic development. To obtain access to this early development stage, IVF or ICSI is
necessary, although the women undergoing this treatment are normally fertile.
The laboratory studies need to be conducted on minimal amount of biological material, which
means biopsy of 1 or 2 cells (blastomeres) out of the 8 cells which are normally developed at day
3. With special techniques it is possible to study these cells. FISH (fluorescent in site
hybridisation) is used to detect the sex and chromosomal abnormalities[1,2]. PCR is used to
diagnose autosomal dominant, autosomal recessive and X-linked monogenic disorders .
Since the first report on clinically applied preimplantation genetic diagnosis (PGD) in 1990 by
Handyside and colleagues in the UK , the number of centres involved in PGD, as well as the
number of PGD treatments has increased year by year.
In 1997 the ESHRE (European Society for Human Reproduction and Embryology) PGD
Consortium was formed as part of the ESHRE Special Interest Group on Reproductive Genetics.
The prospective and retrospective collection of data on availability, accuracy, reliability and
effectiveness of PGD has been one of the major aims of the ESHRE PGD Consortium. In
December 1999, the first PGD Consortium report was published discussing referrals on 323
couples, 392 PGD cycles and 82 pregnancies . In the second data collection round,
contributing centres were asked to send in data from their PGD activities before this date, as well
as from 1 October 1998 to 1 May 2000, in order to have an as complete as possible overview of
PGD practices in these centres. These data have been published recently .
The availability of PGD in Europe has been summarised by Viville and Pergament in 1998 .
A more recent overview representing the situation in September 2000, is given in Table 1. From
this it is clear that a division can be seen between countries with and without legislation
regulating PGD. Some of the countries with legislation have a law allowing PGD (The United
Kingdom, Spain) while it is clear that PGD is not allowed in others (Austria). In Germany the
state of affairs is unclear since the law is interpreted in different ways. In countries without
legislation PGD is sometimes allowed under the guidance of a national authority. Belgium,
Greece, Italy and The Netherlands are examples of this.
In total referral data have been obtained from 886 couples. The vast majority of couples have had
one or more pregnancies. However, healthy children have been born in less than 25 % of them.
More than a quarter of all couples have one or more affected children. Almost the same
proportion of couples has suffered from spontaneous abortion or termination of pregnancy after
This is reflected in the reasons for PGD. The most important reason is genetic risk and objection
to termination of pregnancy (44 %). The group having experienced termination after prenatal
diagnosis is smaller (28 %). In almost one third of the cases (29 %) the genetic indication was
combined with sub- or infertility, which made IVF or ICSI necessary.
If the broad indication groups are considered it is clear that chromosomal indications are
becoming an increasingly important reason for referral. This is most likely a reflection of
The referrals for monogenic disorders shows that cystic fibrosis is the most frequent reason for
referral, followed by thalassemia and spinal muscular atrophy (type I) as far as the autosomal
recessive disorders are concerned. The group of autosomal dominant diseases is dominated by
the trinucleotide repeat disorders myotonic dystrophy (57 couples) and Huntington's disease (44
couples). For the fragile-X syndrome as well as Duchenne/Becker's muscular dystrophy 52
couples were referred. Referrals for several other X-linked diseases were noted. However, in
most cases the numbers were small with the exception of haemophilia and Wiskott-Aldrich
In general it might be concluded that the pattern of referral indications is more or less a reflection
of the genetic disorders requiring prenatal diagnosis. One of the differences that are clearly
present is the number of referrals with the combination of two genetic disorders segregating at
the same time. A total of 7 couples presented with this phenomenon. For the time being it will be
very difficult to help these couples.
In the majority of cases the patients were suitable for IVF or ICSI, and PGD was technically
possible and/or ethically acceptable. For different reasons a total of 199 couples could not be
accepted for PGD. Technical obstacles were the main reason for not being able to offer
diagnosis. In a few cases this had to do with the fact that diagnosis on frozen embryos was
requested. Some patients were referred to a centre that had the test already available. About 9 %
of the patients did not fulfil the criteria for IVF or ICSI. Some patients were simply too old,
others showed a high FSH. IVF was also considered risky to the mother in some cases of
myotonic dystrophy and spinal muscular atrophy. One of the ethical objections was in the case of
nondisclosure testing for Huntington's disease.
The reasons for declining show that the largest group quits because of the burden of the
procedure followed by the low success rate. Financial aspects appear to play a minor role. It is
also interesting to note that in 21 cases a spontaneous pregnancy was the reason for declining.
Cycle data were obtained on 1319 cycles.
Screening for chromosome abnormalities was done in 465 cycles. All patients were infertile and
the indications included repeated IVF failure, maternal age, and recurrent abortion. From a total
of 6025 oocytes retrieved a fertilisation rate of 62 % was achieved. Seventy-nine percent of
cycles resulted in an embryo transfer, although for a number of cycles no embryos were
diagnosed as transferable, and embryos were still transferred. This is reflected in the data by the
fact that the number of embryos transferred is more than the number of embryos transferable.
The hCG levels were not recorded by one centre, but the clinical pregnancy rate was 29% per
oocyte retrieval and 36% per embryo transfer procedure.
All other cycles, a total of 843 cycles were started because of true PGD. About 10 %, 82 cycles,
were cancelled before the oocyte retrieval due to a poor response, cysts or other reasons (9.7%
cancellation rate). Seven hundred and seventy-one cycles reached the stage of oocyte retrieval.
From 10267 oocytes collected, a fertilisation rate of 63 % was obtained. The number of oocytes
inseminated is not an accurate figure, as some centres did not record this information. From the
6465 fertilised oocytes, 81% were suitable for biopsy, of which 96% were successfully biopsied,
which is consistent with the data for last year. The majority of cases had cleavage stage biopsy
(755 cycles) all of which used blastomere aspiration to remove the cell.
The diagnosis was obtained in 86 % of embryos successfully biopsied, and of these, 46 % were
diagnosed as suitable for transfer. From the number of oocytes collected, only 18 % were finally
diagnosed as suitable for transfer, which confirms the need for the retrieval of a high number of
oocytes for a successful PGD cycle. A total of 639 cycles reached the embryo transfer stage and
1340 embryos were transferred. In this series, 360 embryos have been cryopreserved, and some
have been thawed and transferred, but there has been no publication reporting a pregnancy from
A positive hCG was detected in 174 cycles (23 % per oocyte retrieval) and 141 were confirmed
as clinical pregnancies following an ultrasound scan (16.5 % per started cycle, 18 % per oocyte
retrieval, 22 % per embryo transfer procedure).
When the cycles were separated according to the diagnostic method used, the following results
were obtained: PCR diagnoses were performed for a variety of autosomal recessive and
dominant disorders and for sexing or specific diagnosis for X-linked diseases. For the PCR
diagnosis, 385 cycles reached oocyte retrieval. It is well documented that for PCR diagnosis
fertilisation should be achieved by ICSI to reduce the risk of contamination from sperm
embedded in the zona pellucida, but still IVF was used in 35 cycles. A successful PCR diagnosis
was obtained in 81% of embryos successfully biopsied, and 55 % were diagnosed as
transferable. A pregnancy rate of 22 % per oocyte retrieval and 26 % per embryo transfer
procedure was obtained.
FISH was used for the diagnosis of sex for X-linked disease and patients carrying Robertsonian
and reciprocal translocations. More X-linked diseases can be diagnosed by a DNA-specific test,
which obviates the need for sexing by FISH.
For the FISH diagnosis, 386 cycles reached the stage of oocyte retrieval. A successful diagnosis
was obtained in 90 % of embryos successfully biopsied and of these only 32 % was diagnosed as
suitable for transfer. This was mainly due to the high levels of abnormal embryos detected for
patients carrying translocations. PGD for chromosome analysis mainly involved patients
carrying Robertsonian or reciprocal translocations. From a total of 196 cycles that reached the
oocyte retrieval stage, ICSI was performed in most cases, some of which were probably because
of poor sperm quality due to the male carrying the translocation. One cycle had IVF and ICSI.
Three cycles were cancelled after the oocyte retrieval, probably due to insufficient embryo
development. Acidic Tyrode’s was used for drilling in 157 cycles. Polar body biopsy was used
for three cycles and cleavage stage aspiration for 190 cycles. From the 2732 oocytes collected,
85 % were fertilised, which was higher than for other types of PGD cycles. Of these, 85 % of the
embryos were considered suitable for biopsy. The embryo biopsy procedure was successful in 95
% of cases and a FISH result obtained in 90 % of embryos. Only 27 % of the embryos
diagnosed were considered suitable for transfer, which was just 13 % of the oocytes collected.
This reflects the high level of abnormal embryos detected in this group of patients. In 19 % of
cycles there were no embryos suitable for transfer. A clinical pregnancy rate of 19 % per embryo
transfer procedure and 15 % per oocyte retrieval was obtained. The low number of embryos
available for transfer after PGD for chromosomal aberrations is one of the subjects of study.
Pregnancy data were obtained on 163 pregnancies. The high rate of multiple pregnancies (31 %)
was in contrast to the moderate pregnancy rate per cycle (16.5 %). Although several publications
have now shown that careful selection of one or two viable embryos for transfer is effective in
reducing multiple pregnancies, this type of selection is not easily applicable in PGD. First of all,
it is still unclear to what extent biopsy of one or two cells from an embryo impairs the
implantation potential. Secondly, at each PGD a cohort of embryos is diagnosed as unsuitable for
transfer on genetic grounds, while this cohort could well contain the embryos with the highest
implantation potential. Thirdly, PGD embryos are transferred at day three or day four, while
most IVF centres now transfer embryos in regular ICSI patients at day 2 or sometimes at day 5 at
the blastocyst stage, which makes comparing pregnancy rates after PGD and ICSI difficult.
Clearly, the PGD Consortium data collection would be an ideal tool for investigating what
selection criteria apply to embryos post biopsy. Up to May 2000, data on 163 pregnancies and
224 foetal sacs have been collected, the oldest of which date from 1993. Thirty-two of the 224
foetal sacs were lost during the first trimester, leading to 138 pregnancies, which went on to the
second trimester. During the second trimester, seven pregnancies were lost, two most notably by
TOP after misdiagnosis discovered at prenatal diagnosis. Five triplet and one quadruplet
pregnancies were reduced to one singleton and five twin pregnancies. Hundred and thirty-one
pregnancies went on normally, five of which were ongoing by May 2000, three for which no
further information was available, and 123 which had delivered (85 singletons, 37 twins and 1
triplet). The reason why so few ongoing pregnancies are recorded is that centres were asked to
send in pregnancy and baby data when the pregnancy was completed, either through birth,
miscarriage, or other reasons.
Complications of pregnancy were obtained for 95 pregnancies for which complete information
was available. Complications occurred in a total of 31 pregnancies with more than one
complication reported for some pregnancies. An important proportion of these complications
(preterm labour, premature rupture of membranes) originated from multiple pregnancies, as is
also illustrated by the rate of complications (calculated on the totality of deliveries) in singletons
(22 %) as compared to twins (32 %).
The incidence of pregnancy loss (subclinical pregnancies (i.e. pregnancies with a positive hCG,
but no foetal heart beat), clinical abortions and extra uterine pregnancies) was 30/163 or 18.4 %,
which is comparable to the 22.4 % mentioned by Wisanto et al. (1995) for ICSI with ejaculated
sperm. However, caution is mandatory because the retrospective nature of the data collection
may lead to underestimation of chemical pregnancies could be underreported. Reassuringly, no
specific complication emerges which could be linked to PGD.
Not surprisingly, a higher level of prematurity (51 % for twins vs. 9 % for singletons) and
delivery by C-section (54 % for twins vs. 35 % for singletons) was seen in the twins.
Data reported on 162 live born children were collected. The sex ratio is heavily skewed towards
female children due to the high number of girls born after sexing for X–linked diseases. The
average birth weight for 145 children was 2824 g, with an average of 3206 g for 81 singletons
and 2344 g for 64 twins. The average birth length was 47.5 cm (n=93) and the average head
circumference was 33.2 cm (n=60). Apgar scores were good (≥ 8 at birth) in 78 out of 82
children and bad (< 8 at birth) in four children, three of which showed a good further evolution
and one of which, a severely premature child, died.
The presence or absence of malformations was available for 130 children; 121 of these showed
no malformation. (Again it can be assumed that the 32 for which no information was given did
not show malformations). Seven children showed non life-threatening malformations ranging
from Mongolian spot to bilateral clubfoot and two children died due to severe malformations
(exencephaly and chylothorax). No information on possible surgical correction is available since
this type of information was not requested.
The cohort of 162 children described here is very similar to a cohort of 1987 children born after
'regular' ICSI described by Bonduelle et al. : 52 % and 54 % were singletons, 46 % and 41 %
were twins, and 2 % and 5 % were triplets respectively. Other parameters such as birth weight
were also very similar: singletons weighed 3206 g and 3220 g and twins weighed 2344 g and
2421 g respectively. Birth length and head circumference were equally similar. When we apply
the definition of major malformation used in this publication (i.e. malformations that generally
cause functional impairment or require surgical correction), we obtain a rate of 3/130 (bilateral
clubfoot, exencephaly and chylothorax) or 2.3 %. Again, this is very close to the 2.9 % obtained
by Bonduelle et al. . Although the numbers are still small, an important message to emerge
here is dealing with one of the first concerns of the ESHRE PGD Consortium in that PGD babies
are not exposed to greater risks of neonatal problems or malformation than ICSI babies.
Confirmation of diagnosis
In total, 116 of the 236 foetal sacs (49 %) were examined through prenatal diagnosis. Four cases
unfortunately were shown to be misdiagnosed at PGD. Two of these pregnancies (one affected
with myotonic dystrophy and one with β-thallassemia) were terminated, while the two other
pregnancies (one with cystic fibrosis and one male foetus after sexing for X-linked retinitis
pigmentosa) went on to term. Whether this boy is affected with RP is not known. The obvious
confirmation of PGD for sexing by the baby’s sex at birth is not taken into account. After PGD
for sexing only one misdiagnosis (see above), which was discovered at prenatal diagnosis,
occurred after preimplantation sex determination using PCR. In four early miscarriages a
karyotype was obtained: two miscarriages showed an abnormal karyotype (one trisomy 16 and
one mosaic trisomy 22). Although both abnormal karyotypes occurred in the FISH group, these
cannot be classified as misdiagnoses since the involved chromosomes were not examined at
The four misdiagnoses for monogenetic diseases shows the greater technical difficulties
encountered with PCR than with FISH. One of these misdiagnoses was probably due to
contamination during PCR; for the other three no explanation was given or available, although it
would be interesting to know why these misdiagnoses occurred in order to prevent such events in
the future, possibly through guidelines issued by the PGD Consortium.
Many couples referred for PGD have had affected children and/or have objections to termination
of pregnancy after prenatal diagnosis. The parental ages of the couples are increased. The
pregnancy rates are not yet in agreement with a fertile population. Most probably this results
from the increased parental ages and the reduction of the number of embryos available for
transfer. Misdiagnosis occurs in about 2-4% and is a serious problem. There is no evidence for
an increase of congenital abnormalities other than from the increased rate of multiple
pregnancies. Although not all of these data are encouraging, the practice of PGD is becoming
more and more established and more and more different applications are emerging.
1. Staessen C, Van Assche E, Joris H et al. Clinical experience of sex determination by
fluorescent in-situ hybridization for preimplantation genetic diagnosis. Mol Hum Reprod 1999;
2. Scriven PN, Handyside AH and Mackie Ogilvie C. Chromosome translocations: segregation
modes and strategies for preimplantation genetic diagnosis. Pren Diagn 1998; 18: 1437-1549.
3. Wells D and Sherlock JK. Strategies for preimplantation genetic diagnosis of single gene
disorders by DNA amplification. Pren Diagn 1998; 18: 1389-1401.
4. Handyside AH, Kontogianni E, Hardy K et al. Pregnancies from biopsies human
preimplantation embryos sexed by Y-specific DNA amplification. Nature 1990; 344: 768-770.
5. Viville S and Pergament D. Results of a survey of the legal status and attitudes towards
preimplantation genetic diagnosis conducted in 13 different countries. Pren Diagn 1998; 18:
6. ESHRE PGD Consortium Steering Committee. ESHRE Preimplantation Genetic Diagnosis
(PGD) Consortium: preliminary assessment of data from January 1997 to September 1998. Hum
Reprod 1999; 14: 3138-3148.
7. ESHRE PGD Consortium Steering Committee. ESHRE Preimplantation Genetic Diagnosis
(PGD) Consortium: data collection II (May 2000). Hum Reprod 2000; 15: 2673-2683.
8. Bonduelle M, Camus M, De Vos A. et al. Seven years of intracytoplasmic sperm injection and
follow-up of 1987 subsequent children. Hum Reprod 1999, 14 (suppl. 1): 243-264.
COUNTRY PGD PGD PERMITTED NUMBER OF
REGULATED BY CENTRES
Austria + - 0
Belgium - + 1
Denmark + + 1
Finland + + 0
France + + 2
Germany + ? 0
Greece - + 1
Italy - + 2
Norway + + 0
Spain + + 2
Sweden + + 2
The Netherlands - + 1
United Kingdom + + 4
Name: J.P.M. Geraedts
Date of birth: 17 April 1948
Place of birth: Swalmen
Address Kerkstraat 79
6267 EB Cadier en Keer
Civil status Married with 2 children
1960-1965: Episcopal College Roermond
Secondary school-leaving certificate
1965.1972 Catholic University of Nijmegen
04-06-1969: Degree in biology
01-02-1972: Master's in biology
05-11-1975: Doctorate, University of Leiden with a thesis on:
Constitutive heterochromatin as a marker for chromosomal
studies in human somatic cells and spermatozoa.
29-11-1985: Registered human geneticist (SMBWO: Institute for
Medical and Scientific Research)
1972-1975: University clinic, Leiden
1975-1982: University of Leiden
(chief) scientific assistant
1983-present University of Maastricht
Professor of genetics and cell biology
Stichting Klinische Genetica Zuid-Oost Nederland:
Director (since 1983)
Stichting Beheer Gebouw Drie-X Factoren:
President (since 1995)
Stichting Medisch Biologisch Wetenschappelijk Onderzoeker
Member of board (1983-1989)
Chairman of the Human Genetics Assessment Panel (1983-1989)
Stichting Netwerk Zwakzinnigenzorg Benelux:
Secretary/Treasurer (since 1991)
Stichting Automatisering Klinisch Genetische Registratie:
Chairman of the steering group (1989-1993)
Nederlandse Anthropogenetische Vereniging:
Member of board (1981-1985)
VERENIGING VAN STICHTINGEN KLINISCHE GENETICA:
Member of board (1993-2000)
President (since 2000)
Member of the negotiating committee (since 1994)
Member of the health insurance advisory committee (since 1996)
Member of the interdisciplinary Human Genome Analysis committee (1994-1998)
Secretary, working party on chromosome and gene analysis (since 1990)
Organiser of the annual retreat in Rolduc (since 1991)
Member of the Transgene Organism committee (1994-1997)
Member, committee on animal experiments, transgenesis and biotechnology (since 1997)
Stichting Biowetenschappen en Maatschappij:
Member of board (since 1996)
European Society of Human Genetics and Embryology:
Member of Preimplantation Genetic Diagnosis consortium (since 1997)
Coordinator Special Interest Group Reproductive Genetics (since 2000)
Member, International Scientific Committee (since 2000)
Member, International Advisory Committee (since 2000)
Saudi Arabian Fertility Society:
Member, International Advisory Committee (since 1998)
Maastricht University Clinic:
Member, IVF Committee (since 1992)
Member, 'Effects of Prevention' group of experts; 1997 health surveys
University of Maastricht:
Head of division, development biology, GROW research institute
Chairman, research trainees committee (1992-1994)
Chairman, medical faculty examination board (1994-1998)
Member of examinations appeal board (since 1998)
Dutch member of jury, European Union Contest for Young Scientists (1995-1997)
Membership of editorial boards:
Medische Genetica (since 1983)
Dezen en Genen (since 1989)
Balkan Journal Medical Genetics (since 1997)
Prenatal Diagnosis, PGD section (since 2000)
Mediator (since 2000)
Membership of academic bodies:
Nederlandse Anthropogenetische Vereniging (since 1972)
European Society of Human Genetics (since 1972)
Nederlandse Genetische Vereniging (since 1979)
Nederlandse Vereniging voor Oncologie (since 1981)
Nederlandse Vereniging voor Celbiologie (since 1982)
European Society of Human Reproduction and Embryology (since 1988)
America Society of Human Genetics (since 1993)