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màj 23/07/98 |
Report
by Dany Jaffuel on the following session :
| Vendredi
13 Février 1988 |
Présentateurs/Speakers
|
Modérateurs
|
Experts
|
10h30-11h30
|
Epidémiologie -
Génétique
|
F. Demenais
(Paris)
C.
Pison (Grenoble)
Discussion
|
15'
15' 30'
|
D.
Charpin (Marseille)
Ph. Godard
(Montpellier)
|
J.
Anton (Barcelone, E)
G. Koppelman (Groningen, NL)
|
During this
session were presented preliminary results of the French
cooperative Epidemiologic study of the Genetics and
Environment of Asthma (EGEA study). Objectives of the EGEA are to
identify the genetic and environmental factors involved
in asthma, bronchial responsiveness, atopy and to
elucidate the gene-environment interactions. Patients
with asthma ascertained from chest clinics of 5 cities
(Paris, Lyon, Marseille, Montpellier and Grenoble) and
their first-degrees relatives and spouses were examined
with a standard protocol. Control subjects matched for
age, month of exam, and city were evaluated with the same
protocol. All probands and their two parents were born in
France. Family structure (either proband with a spouse
and at least one child, or proband with at least one
sibling and 2 parents) and a positive answer to 4
questions (1-Have you ever had attack of breathessness
at rest with wheezing ? 2- Have you ever had asthma
attacks ? and if yes, 3- Was the diagnosis confirmed by a
physician ? 4- Have you had an asthma attack in the last
12 months ? ) were needed to include probands. Cases (213
adults, 135 children) relatives, spouses, and control
subjects (416) totaled 1,854.
|
Data concerning the
epidemiological characteristics of the population studied were
presented by Ch. Pison. The most controversial points of this presentation were criteria used
for patient severity. There were only three steps of severity in
this study (mild asthma, intermediate asthma and severe asthma).
The prevalence of severe asthma was 24,6% and asthmatics were
classified as severe if they experienced more than 1 asthma
attack per week and breathlessness with activity limitation
between attacks or severe dyspnea on exercise, or FEV1<60%
predicted, or hospitalization in the past year for asthma, or at
least once in the ICU.
Discussion:
Dr Anto
emphasized that it's
difficult, in retrospective
study, to appreciate the time
sequence of symptoms and treatment and so the severity of asthma.
Dr Pison agreed with that considering asthma severity closely
related with long-term
treatment in compliant patient (enough this was not included in
the severity classification of the study) and asthma activity
closely related with symptoms.
Dr Godard
suggested that a correct assessment of severity require at least
one year of follow-up. Because genetics status can not change but
asthma severity can be modified, a longer follow up is need if one of the
objective of the study is to determine if there is a familial aggregation for
severe asthma.
Dr Fabbri
underlined that asthma severity differ with criteria used but
also with population studied and in particular socio-economical
status of this population.
Preliminary data concerning the
genetics aspects of this study were presented by F. Demenais. A total of 227 individuals belonging to
the first set of families were genotyped for 263 microsatellites
markers located at 15-20cM over the whole genome. Phenotypes
analyzed were: asthma, bronchial responsiveness, skin test
response, immunoglobulin E levels, atopy, eosinophil counts.
These analyses showed 15 regions of potential linkages with at
least one of the phenotype study. A few linkage regions (chromosomes 6, 7,
11, 12, 13) were previously reported in the literature and new
ones were also detected. Because some of linkage are surprising
(atopy and skin test seems to be linked to chromosome 7 whereas
IgE is linked to 6p), confirmation of results is currently
investigated in the second set of families and candidate regions
are explored specifically.
Discussion:
Dr Koppelman
emphasized that in this type of study (multicentric), it's difficult to have a closely related
control group in particular for environmental factors.
Dr Holgate
suggested that more patients are need to perform genetic studies
and so, he would enjoyed that EGEA group joined his group to pool
results. Dr Demenais underlined that a limitation for pooling
results will be that it is possible only for patients with the
same phenotype.
Dr Anto
concluded that objectives of EGEA group will be to determinate
if:
- there is a familial
aggregation for severe asthma.
- there is a specific genetic
control for severe asthma.
- there are particular
phenotypes of severe asthma.
- there are relevant
gene-environment interaction in severe asthma.
. 
Enfumosa Congrès Conçue et réalisée par: Michel Godard (at) Top
Date de création: 12 Février 1998 -Dernière mise à jour: 23/07/98
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