2008 Barcelona - European Society of Human Genetics

Clinical genetics
are indeed more difficult to detect and characterize. Of the four CFTR
duplications reported, three were detected in our laboratory by QFM-
PCR, in two CF patients and a CBAVD patient . They involved exons
4-8, 10-18 and 11-13, respectively, in trans of another CFTR mutation .
Methods: The duplications were characterized by using a combination
of long-range (LR) PCR, digestion of LR-PCR products and sequencing
. Results: Two duplications were fully characterized, in direct
tandem each: dup10_18 (≈70kb long), and dup11_13 (≈17kb long).
Characterization of the remaining dup4_8 is in process . However,
given the classical CF phenotype of the patient, we hypothesize that
the duplicated region is located inside the CFTR gene and interferes
with the transcription, translation or maturation process, thus resulting
in a null mutation . Conclusion: Effective tools are required to detect
duplications, which may indeed be under-diagnosed. Refinement of
the breakpoints is important to confirm a deleterious effect and should
contribute to understand the duplication mechanism .
P01.029
A French collaborative study indicative of a very low classicalcF
penetrance of R117H; implications for genetic counselling.
C. Thauvin-Robinet 1 , A. Munck 2,3 , F. Huet 1,2,4 , G. Bellis 5 , E. Gautier 6 , C. Férec 7 ,
M. Audrézet 7 , M. Claustres 8 , M. Des Georges 8 , G. Lalau 9 , T. Bienvenu 10 , E.
Bieth 11 , B. Gérard 12 , I. Sermet 13 , G. Rault 14 , J. Flori 15 , J. Lafitte 16 , G. Bellon 17 ,
D. Hubert 18 , C. Binquet 6 , L. Faivre 1 , M. Goossens 19,20 , M. Roussey 2,21 , E. Girodon
19,20 ;
1 centre de génétique, Dijon, France, 2 AFDPHE, Paris, France, 3 CF Care Centres,
Paris, France, 4 CF Care Centres, Dijon, France, 5 INED, Paris, France,
6 CIC-CEC, CHU, Dijon, France, 7 CF laboratory Network, Brest, France, 8 CF
laboratory Network, Montpellier, France, 9 CF laboratory Network, Lille, France,
10 CF laboratory Network, Hôpital Cochin,, Paris, France, 11 CF laboratory Network,
Toulouse, France, 12 CF laboratory Network, Hôpital Robert Debré, Paris,
France, 13 CF Care Centres, Hôpital Necker-Enfants Malades, Paris, France,
14 CF Care Centres, Nantes, France, 15 CF Care Centres, Strasbourg, France,
16 CF Care Centres, Lille, France, 17 CF Care Centres, Lyon, France, 18 CF Care
Centres, Hôpital Cochin, Paris, France, 19 CF laboratory Network, Créteil,
France, 20 Laboratoire de Génétique Moléculaire, Hôpital Henri Mondor, Créteil,
France, 21 CF Care Centres, Rennes, France.
Background: The R117H-associated phenotypes vary from classical
CF to no clinical disease and have made genetic counselling difficult.
Since implementation of CF NBS, the observed high R117H frequency
among neonates with elevated IRT and two mutations has reinforced
this issue . Methods: Two retrospective studies were conducted: 1) a
phenotypic study on 263 patients with two CFTR mutations including at
least one R117H; 2) a retrospective 2002-2005 epidemiological study,
aimed to determine the frequency of R117H and other frequent mutations
in about 6000 healthy individuals without family history of CFTR
pathology . Results: 1) Among the 263 patients, including 92 neonates,
detailed clinical features were available for 247: severe classical CF,
n= 2; isolated CBAVD, n= 60; other CFTR-related disorders (CFTR-
RD), n= 109; healthy, n= 76 (65 neonates, reduced follow up period);
2) Based on R117H and F508del allelic frequencies in the general
population of 0 .25% and 1 .0%, respectively, the [F508del]+[R117H]
genotype prevalence was evaluated at 1/20,000, the CFTR-RD penetrance
at 4 .2% and the CF penetrance at 0 .06% . Conclusion: The very
low penetrance of R117H with regard to classical CF leads to consider
R117H no longer as a CF-causing mutation and to reassure patients
and their families in view of genetic counselling .
P01.030
the molecular genetic study CFTR gene in the group of Russia
cF-patients
A. A. Stepanova, N. V. Petrova, A. V. Polyakov;
Research Centre for Medical Genetics, Moscow, Russian Federation.
Cystic fibrosis (CF) is a common and generally severe autosomal recessive
disorder in the European population, caused by mutations in
the cystic fibrosis transmembrane conductance regulator gene (CFTR)
on chromosome 7q31 .
In the Russian population, cystic fibrosis is characterized by the presence
of two prevalent mutations, the F508del and CFTRdele2,3, which
account for ~55% and ~6% of the CF alleles, respectively .
This study includes 120 unrelated Russian CF patients affected by a
classical form of cystic fibrosis.
Using a comprehensive CFTR gene analysis protocol (ΔF508, ΔI507,
1677delTA, 2143delT, 2184insA, 394delTT, 3821delT, L138ins, G542X,
W1282X, N1303K, 3849+1C-T, R334W, CFTRdele2,3) mutations have
been previously identified in 112/120 (93,3%) patients including 76
(63,3%) with two revealed mutations and 36 (30%) with one revealed
mutation . The current study present the result of investigations by using
a commercial kit (CF OLA assay, Abbot, Rungis-France) in the 44
remaining samples with only one or without revealed CFTR mutation .
Three CFTR mutations at four patients have been in addition identified.
Mutation 2789+5g>a was identified in two patients (0,8%). Two mutations
were identified in one patient each (0,4%): R1162X, 3120+1g>a.
Mutations identified by using a commercial kit in addition in 4 (1,6%) of
the 240 CFTR chromosomes in investigated group .
P01.031
Identification of novel mutations in the Cystic Fibrosis
transmembrane conductance Regulator (CFTR) gene in the
Greek population
M. Poulou1 , M. Mastrominas2 , K. Pantos3 , S. Doudounakis4 , E. Kanavakis1 , M.
Tzetis1 ;
1 2 Department of Medical Genetics, Athens University, Athens, Greece, Embryogenesis
Centre for Reproductive and Fertility Studies, Athens, Greece, 3Centre for Human Reproduction, Genesis Hospital, Athens, Greece, 4Cystic Fibrosis
Clinic, St Sophia’s Children’s Hospital, Athens, Greece.
Cystic Fibrosis is the most common autosomal recessive disorder, with
5% carrier rate in the Greek population . The Greek population has one
of the highest rates of CFTR mutation heterogeneity .
In this study we report 16 novel variants in the CFTR gene identified
by DGGE analysis and direct sequencing. Of these five were synonymous
variants, 7 missense mutations, 2 frameshift mutations leading
to premature termination codon and two intronic substitutions . The effects
of these mutations were assessed in combination with the clinical
phenotype and using in silico analysis . The missense mutations were
assessed using “PolyPhen” and “SIFT” . The impact of the silent mutations
and the intronic substitutions on splicing elements was analysed
using “SSF: Splicing Sequences Finder”. Majority of findings included
changes in splicing factor binding .
Novel Mutation/ Other cFtR mu-
case clinical Phenotype Polyphen siFt
variant
tation/ variant
c .538_539insAC
111 .5 mEq/L; Classical
1
F508del
(L136H-fs153X)
CF; 3 mos
c .3946_3947delTG
2
(V1272Vfs1300X) F508del
118 .6mEq/L;
Classical CF ; 2 yrs
Fetal Echogenic bowel;
possibly
3 F319V TG11T5/ TG11T7 meconium ileus;
T 0 .48
damaging
59 .5 mEq/L
90meq/L; azoospermia; Probably
4 L541P N1303K
NT 0 .00
38yrs
Damaging
5 L1227L P936T Failure to Thrive; 6yrs
Probably
6 P936T Oligospermia
T 0 .38
Damaging
7 R1158R T966I Oligoasthenospermia
8 D1275D
50mEq/L; Malabsorption
Syndrome; 5 yrs
9 2622+3A>G* Oligospermia
10 V1212F GP
possibly
T 0 .42
damaging
11 F305V GP benign T 0 .33
12 2752-18delT* GP
13 S511C Azoospermia benign T 0 .06
14 L1414S GP
possibly
T 0 .06
damaging
15 L1408L Bronchiectasis; 30yrs
16 L346L
Pancreatic Dysfunction;
7yrs
* possible spicing mutation;
GP: General Population; NT: not tolerated; T: Tolerated
P01.032
Molecular-genetic and clinical analysis of cystic fibrosis in
Republic of moldova
N. I. Barbova 1 , V. V. Egorov 2 , A. P. Gavriliuc 2 ;
1 State University of Medicine and Pharmaceutics “N. Testemitanu”, Chisinau,
Republic of Moldova, Chisinau, Republic of Moldova, 2 National Center of Reproductive
Health and Medical Genetics, Chisinau, Republic of Moldova.
Objective: We intended to study relations between genetic and clinic
polymorphism in patients with cystic fibrosis (CF).