GENEVA, November 25 - Merck Serono, a division of Merck KGaA, Darmstadt, Germany, announced
today the launch of a website dedicated to phenylketonuria (PKU), a rare
inborn metabolic disorder. Developed in collaboration with healthcare
professionals and dieticians, the website aims to provide patients living
outside of the United States [1], with a reliable and extensive source of
information on the disease and its management, including practical tips for
everyday life.

"After the launch in Europe of Kuvan(R), the first pharmaceutical
treatment option for PKU, Merck Serono is pleased to provide further support
to patients and their families with a new website", said Roberto Gradnik,
Executive Vice President, Commercial Europe at Merck Serono. "The website
provides clear information addressing the different needs of anyone affected
by this disease, whether patients, families with children suffering from PKU,
or patients seeking to start a family."

Over time, the website will be enriched with new tools and additional
languages. The website is currently available in English and accessible via:
www.pku.com/en. French, German, Italian and Spanish versions are
expected to be available by the end of 2009, while versions in other
languages are planned for 2010.

PKU is an inherited disorder whereby the body fails to break down an
essential amino acid called Phenylalanine (Phe), which can be found in
protein-rich food. In patients suffering from PKU, a long lasting excess
level of Phe in the blood may lead to irreversible neurological disorders in
children, and cognitive deficits and psychiatric disorders in adults. At
present, the management of PKU consists of lifelong dietary restrictions
limiting the Phe intake, often combined with food supplements or substitutes.
Used with a restricted Phe diet, Kuvan(R) has been shown to help control
blood levels of Phe in patients suffering from PKU.

About phenylketonuria (PKU)

PKU, a genetic disorder affecting approximately 50,000
diagnosed patients in the developed world, is caused by a deficiency of the
enzyme phenylalanine hydroxylase (PAH). PAH is required for the metabolism of
phenylalanine (Phe), an essential amino acid found in all protein-containing
foods. If the active enzyme is not present in sufficient quantities, Phe
accumulates to abnormally high levels in the blood and brain, resulting in a
variety of complications including severe mental retardation and brain
damage, mental illness, seizures and tremors, and cognitive problems. As a
result of global newborn screening efforts implemented in the 1960s and early
1970s, virtually all PKU patients in developed countries are diagnosed at
birth.

About Kuvan(R)

Developed by Merck Serono and BioMarin Pharmaceutical Inc.
(Nasdaq and SWX: BMRN), Kuvan (sapropterin dihydrochloride), is an oral
therapeutic and the first treatment indicated in Europe for the treatment of
hyperphenylalaninemia (HPA) due to phenylketonuria (PKU) in patients over the
age of 4; or due to tetrahydrobiopterin (BH4) deficiency. Kuvan is the
synthetic form of 6R-BH4, a naturally occurring enzyme cofactor that works in
conjunction with the enzyme phenylalanine hydroxylase (PAH) to metabolize
phenylalanine (Phe). Clinical data show that Kuvan produces significant
reductions in blood Phe levels in the subset of patients who are
BH4-responsive.

Most common side effects reported with the use of Kuvan
include headache, runny nose, diarrhea, vomiting, sore throat, cough,
abdominal pain, stuffy nose and low levels of phenylalanine in the blood.

Kuvan is approved in 32 countries, including member states of
the European Union and the USA. Under the terms of the agreement with
BioMarin, Merck Serono has exclusive rights to market Kuvan in all
territories outside the USA, Canada and Japan.

About Merck Serono

Merck Serono is the division for innovative prescription
pharmaceuticals of Merck KGaA, Darmstadt, Germany, a global pharmaceutical
and chemical company. Headquartered in Geneva, Switzerland, Merck Serono
discovers, develops, manufactures and markets innovative small molecules and
biopharmaceuticals to help patients with unmet medical needs. In the United
States and Canada, EMD Serono operates through separately incorporated
affiliates.

Merck Serono has leading brands serving patients with cancer (Erbitux(R),
cetuximab), multiple sclerosis (Rebif(R), interferon beta-1a), infertility
(Gonal-f(R), follitropin alpha), endocrine and metabolic disorders (Saizen(R)
and Serostim(R), somatropin), (Kuvan(R), sapropterin dihydrochloride) as well
as cardiometabolic diseases (Glucophage(R), metformin), (Concor(R),
bisoprolol), (Euthyrox(R), levothyroxine). Not all products are available in
all markets.

With an annual R&D expenditure of around EUR 1bn, Merck Serono
is committed to growing its business in specialist-focused therapeutic areas
including neurodegenerative diseases, oncology, fertility and endocrinology,
as well as new areas potentially arising out of research and development in
autoimmune and inflammatory diseases.

About Merck

Merck is a global pharmaceutical and chemical company with
total revenues of EUR 7.6 billion in 2008, a history that began in 1668, and
a future shaped by approximately 33,000 employees in 60 countries. Its
success is characterized by innovations from entrepreneurial employees.
Merck's operating activities come under the umbrella of Merck KGaA, in which
the Merck family holds an approximately 70% interest and free shareholders
own the remaining approximately 30%. In 1917 the U.S. subsidiary Merck & Co.
was expropriated and has been an independent company ever since.

For more information, please visit www.merckserono.com or
www.merck.de

———————————

[1] The website www.pku.com is already available to PKU patients
and their families living in the US and is managed by BioMarin, Merck
Serono's development partner.

Merck Serono, 9 Chemin des Mines, 1202 Geneva, Switzerland, Media Relations: +41-22-414-3600