2008 Barcelona - European Society of Human Genetics

Clinical genetics
L185R missense mutation, previously reported in EE patients, were
shown to be associated with the absence of the ETHE1 protein .
P01.056
mutation analysis of Fabry disease in Argentina
G. P. Serebrinsky 1 , F. M. Masllorens 2 , H. Amartino 3 , R. Valdez 4 , A. Fainboim 5 ,
G. Cabrera 6 , J. M. Politei 7 ;
1 Laboratorio de Biología y Patología Molecular, Buenos Aires, Argentina,
2 Hospital Nacional Profesor A. Posadas, Buenos Aires, Argentina, 3 Hospital
Universitario Austral, Servicio de Neurología Infantil, Pilar, Provincia de Buenos
Aires, Argentina, 4 Hospital Alemán, Servicio de Genética Médica, Buenos Aires,
Argentina, 5 Hospital de Niños Ricardo Gutierrez, Centro de enfermedades
lisosomales, Buenos Aires, Argentina, 6 Clínica Adventista, Buenos Aires, Argentina,
7 Sección Neurología, Instituto de Neurociencias, Fundación Favaloro,
Buenos Aires, Argentina.
Fabry disease is an X-linked inborn error of glycosphingolipid metabolism,
resulting from mutations in the alpha-galactosidase A gene
(GLA) . Very few reports on mutation analysis for Fabry disease in
the Argentinean population are available in literature . Here we report
mutation analysis in 16 unrelated Argentinean families with Fabry disease
. Methods: Genomic DNA was isolated from affected males and
female relatives, and the entire alpha-Gal A coding as well as flanking
intronic sequences were amplified by PCR and analyzed by automated
sequencing .
Results: Thirteen different mutations were identified, including eight
missense mutations (D155H, C174G, C202Y, N215S, Y216C, D264Y,
A292T, L415P); two nonsense (R227X, E398X); one splice site mutation
IVS4-1G→A and two small deletions: one complex G144fsX15
(del c .431-442, del c .448-459) and K374fsX15 (del c .1122-1125 del
AGGA) . Six were novel mutations (underlined) and seven were previously
described. Mutation analysis provided precise identification of
33 heterozygotes among female relatives and detected a de novo mutation
(IVS4-1G→A). Discussion: It is generally assumed that Fabry
mutations are private; however this does not seem to be the case of
our sample . Mutation L415P was found in four different families presumably
unrelated by pedigree analysis . Haplotype analyses with microsatellite
markers tightly linked to the GLA gene are being performed
in order to define whether this mutation is recurrent in Argentina or the
result of a founder effect. These studies further define the heterogeneity
of mutations causing Fabry disease and permit precise carrier
identification, which has consequences for genetic counselling and for
treatment .
P01.057
screening for Fabry disease using alpha-galactosidase assay on
dried blood discs : a prospective nationwide multicentric study
D. P. Germain 1 , N. Miri 2 , T. Damy 3 , K. Ly 4 , A. Millaire 5 , P. Charron 6 , A. Martin-
Mista 2 , K. Benistan 2 , T. Tran 2 , E. Caudron 7 , P. Prognon 7 , L. Gouya 8 , C. Boileau 8 ,
A. Bouzamondo 9 , C. Boucly 2 , A. Hagège 10 ;
1 Université de Versailles - St Quentin en Yvelines, Garches, France, 2 Hôpital
Raymond Poincaré, Garches, France, 3 Hôpital Henri Mondor, Créteil, France,
4 CHU, Limoges, France, 5 CHRU, Lille, France, 6 Hôpital Pitié-Salpétrière, Paris,
France, 7 Faculté de Pharmacie, Chatenay-Malabry, France, 8 Hôpital Ambroise
Paré, Boulogne, France, 9 Société Française de Cardiologie, Paris, France,
10 Hôpital européen Georges Pompidou, Paris, France.
Background . Fabry disease (FD, OMIM 301500) is a multisystemic and
clinically heterogeneous disease resulting from a deficiency of the lysosomal
enzyme alpha-galactosidase A . Hypertrophic cardiomyopathy
is a frequent symptom of the classic form of the disease and a cardiac
variant, characterized by residual alpha-galactosidase A activity and a
milder phenotype, has also been reported . In a prospective nationwide
multicentric study, we have studied the prevalence of Fabry disease in a
hypertrophic cardiomyopathy referral population .
Methods. We have developed and validated an assay of alpha-galactosidase
A activity on dried blood paper discs . Using this method, we have
assayed alpha-galactosidase A activity in 330 adult patients affected with
hypertrophic cardiomyopathy who had never been diagnosed with FD .
Results . Three patients (0 .9%) were found to exhibit low alpha-galactosidase
A activity in dried blood spots. This was confirmed by a second
determination of alpha-galactosidase activity in leukocytes . The three
patients presented neither the typical clinical signs of classic FD, such as
acroparesthesias or hypohidrosis, nor kidney insufficiency, suggesting a
variant form of FD . All patients with low alpha-galactosidase activity had
mutations in the GLA gene. DNA sequencing also allowed the identification
of two additional hemizygotes (half-brothers of the proband) in one
family .
Discussion . Screening for Fabry disease should be considered in all
cases of unexplained hypertrophic cardiomyopathy . Its recognition is important
since specific enzyme replacement therapy is now available. The
proposed novel filter paper method favours the collection, storage and
shipment of samples. It is simple and efficient for screening programs.
P01.058
An update in the molecular analysis of classical galactosaemia
in spain and Portugal: Eight new mutations in seventeen new
patients
L. Gort1 , E. Quintana1 , S. Moliner1 , L. González-Quereda1 , T. López-Hernández1
, P. Briones1,2 ;
1 2 Institut de Bioquímica Clínica - CIBERER, Barcelona, Spain, CSIC, Barcelona,
Spain.
Classical galactosaemia is an autosomal recessive inherited metabolic
disorder due to mutations in the galactose-1-phosphate uridyltransferase
gene (GALT) .
We previously reported molecular analysis of 83 Spanish and Portuguese
galactosaemic patients . Here we present the molecular results
of another seventeen unreported affected individuals .
Thirteen patients of Spanish origin were analysed . We detected six
alleles carrying p .Q188R, accounting for 23% . Other six alleles (23%)
were identified with the mutation p.K285N. Remarkably, the two patients
that were homozygous for this change were of North African
origin. We also identified seven novel mutations: p.Q9X, c.328+2T>C,
c .328+33G>A, p .I170N, p .C180F, p .V233L, p .P257L . Taking into account
all the Spanish galactosaemic diagnosed patients, mutation
p.Q188R is still the most frequent mutation identified (43.7%). The second
most frequent mutation is p .L195P (13 .3%) followed by p .K285N
(12 .5%) .
Four new Portuguese patients were analysed . In four alleles p .Q188R
was detected, representing 50%. One novel mutation was identified,
p .F171C . Mutations p .L195P and p .K285N still remain undetected in
Portuguese patients . In the whole group of 36 Portuguese patients we
have analysed until now, mutation p .Q188R remains the most frequent
identified (57%). It is worth mentioning that this is the only frequent
mutation as the rest of changes identified were found only in one or
two alleles each .
Our results confirm the already published observation that p.Q188R
is the most frequent mutation in Iberian Peninsula galactosaemic patients
(48,5%) .
Moreover, our molecular analyses on these seventeen new galactosaemic
patients provide eight novel mutations to the database with
more than 200 disease-causing mutations already reported .
P01.059
Normal HPRt coding region in complete and partial HPRt
deficiency.
M. G. García, R. J. Torres, C. Prior, J. G. Puig;
Hopital La Paz, Madrid, Spain.
Lesch-Nyhan syndrome is an X-linked recessive inborn error of metabolism
due to a virtually complete lack of hypoxanthine-guanine
phosphoribosyltransferase (HPRT) activity (OMIM 300322) . Partial
deficiency of HPRT (OMIM 300323) is characterized by the effects of
excess uric acid synthesis and a continuum spectrum of neurological
manifestations, without the manifestations of full-blown Lesch-Nyhan
syndrome . Both diseases have been associated with mutations
in the HPRT gene . These mutations are heterogeneous and disperse
throughout the entire HPRT gene . In 2005 Dawson et al described,
for the first time, an individual with gout in whom HPRT deficiency appeared
to be due to a defect in gene regulation .
Patients and methods: Four patients with partial HPRT deficiency and
one patient with Lesch-Nyhan syndrome were studied . The RNA and
RNA-free genomic DNA samples were isolated from whole blood .
Analysis of HPRT coding region was performed by Reverse transcription
of patients RNA, amplification of HPRT cDNA by PCR and automated
sequencing . HPRT mRNA expression was determined by Real-
Time PCR technology . All nine exons of the human HPRT gene, its
intronic flanking sequences, and gene regulatory sequences were amplified
and automated sequenced. Results: All patients showed a nor-
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