Merck Serono Initiates KAMPER, the First Pan-European Registry for Patients Under Kuvan(R) Therapy

GENEVA, December 10 - Merck Serono, the pharmaceutical division of Merck KGaA,
Darmstadt, Germany, today announced the enrollment of the first patient in
KAMPER, the Kuvan Adult Maternal Pediatric European Registry. KAMPER is the
first Pan-European registry for patients suffering from
hyperphenylalaninaemia (HPA), due to phenylketonuria (PKU) or
tetrahydrobiopterin (BH4) deficiency, and treated with Kuvan(R) (sapropterin
dihydrochloride).

The registry aims to follow 625 patients over a period of up
to 15 years in order to document the long-term treatment outcomes of
Kuvan(R). Kuvan(R) was granted with an Orphan Drug designation by the
European Commission and received a marketing authorization in December 2008.

"The purpose of the KAMPER registry is to collect additional
information on the benefits and long-term safety of therapy with Kuvan.
Beyond this objective, Merck Serono's goal is to help improve the clinical
care of patients with PKU or BH4 deficiency. The KAMPER registry represents a
significant commitment in this direction", said Bernhard Kirschbaum,
Executive Vice President Research and Development at Merck Serono.

The KAMPER registry is a multi-center observational registry
which will be conducted in specialist clinics across 11 European countries.
Patients over the age of 4 suffering from PKU and all patients with BH4
deficiency, treated with Kuvan(R) are eligible to participate. A maternal
sub-registry will also be open to collect additional data from pregnant
patients under Kuvan(R). An assessment of patients will be performed on a
regular basis according to local practice. Interim analyses of the data
collected will be published over the 15 years of the registry.

About hyperphenylalaninemia (HPA)

Disorders of phenylalanine (Phe) metabolism can lead to
abnormal elevations of blood Phe levels, also called hyperphenylalaninemia
(HPA). Two inborn errors of metabolism, phenylketonuria (PKU) and
tetrahydrobiopterin (BH4) deficiency, account for the majority of cases of
HPA.

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 tetrahydrobiopterin (BH4) deficiency

BH4 deficiency is a very rare inborn error of metabolism, and is
estimated to account for 1-2 % of cases of HPA. BH4 deficiency is an
autosomal recessive genetic condition and can result from deficiencies of any
of the five different enzymes involved in BH4 synthesis and regeneration. BH4
is a necessary co-factor for PAH. Therefore, BH4 deficiency impairs PAH
activity leading to a biochemical situation similar to PKU, with HPA
resulting from deficient conversion of Phe to tyrosine. In addition, since
BH4 is also a necessary co-factor for both tyrosine hydroxylase and
tryptophan hydroxylase, BH4 deficiency causes deficiencies in the downstream
neurotransmitter products of these amino acids including catecholamines and
serotonin. Dietary limitation of whole protein or Phe intake is often not
necessary with BH4 treatment. However, since BH4 does not cross the blood
brain barrier, concomitant therapy with neurotransmitter precursors, i. e.
levodopa and 5-hydroxytryptophan, may be necessary to boost central nervous
system substrate levels for catecholamine and serotonin synthesis,
respectively.

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

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