2009 Vienna - European Society of Human Genetics

Clinical genetics and Dysmorphology
cluding 200 for prenatal diagnosis. The continuous share of experience
with rare variants greatly helps genetic counselling.
Since 2001, six workshops were organized, convening molecular geneticists,
technicians, clinicians of CF care centres and private companies.
Three main topics were addressed: 1) Network functioning, discussion
on best practice guidelines and report on European actions; 2)
technical aspects including new technologies; 3) and clinical issues. A
number of collaborative studies have been published (e.g. Claustres,
Hum Mutat 2000; Muller, Am J Med Genet 2002; Feldmann, Hum Mutat
2003) and others are still ongoing, such as the study of phenotypegenotype
correlations on R117H. The involvement of several of the
Network members in European actions contributes to the dynamism
of the French Network.
P02.119
the prevalence of common cFtR gene mutations and 5t allele
between infertile men in Russia
V. B. Chernykh, T. M. Sorokina, L. V. Shileiko, L. F. Kurilo, A. A. Stepanova, A.
V. Polyakov;
Research Centre for Medical Genetics, Russian Academy of Medical Sciences,
Moscow, Russian Federation.
Introduction: Cystic fibrosis conductance transmembrane regulator
(CFTR) gene mutations are common genetic cause of male infertility.
The frequency and the spectrum of CFTR mutations are variable
between populations.
Materials and methods: We examined a cohort of 850 men from
Russian infertile couples. Fourteen common CFTR mutations
(CFTRdele2,3(21kb), 394delTT, L138ins, R334W, F508del, I507del,
1677delTA, G542X, 2143delT, 2184insA, 3821delT, W1282X, N1303K
and 3849+10kbC>T) and Tn-polymorphism in the intron 8 (IVS8T)
have been analyzed.
Results: CFTR gene mutations were found in 40 (4.7%) patients. Following
heterozygous mutations have been revealed: F508del (n=17),
CFTRdele2,3 (n=7), W1282X (n=6), 2143delT (n=4), 2184insA (n=1),
G542X (n=1), R334W (n=1), 1677delTA (n=1), 3849+10kbC>T (n=1)
and 3821delT (n=1). The presence of 5T allele was found in 96 (11.3%)
infertile men. This CFTR allele has been revealed in the heterozygous
(87,5%), in the homozygous (4,2%) and in the compound heterozygote
state (8,3%) with following common CFTR mutation: F508del (n=4),
CFTRdele2,3 (n=1), W1282X (n=2) and G542X (n=1). Mild (atypical)
forms of cystic fibrosis (CF) with extragenital features of CF (with a
presence of chronic bronchitis or chronic pancreatitis) were diagnosed
in 4 (0.5%) infertile men. CBAVD and/or obstructive azoospermia were
revealed in about 2% of examined individuals. One severe oligozoospermic
patient presented with unilateral renal agenesis (URA) associated
with CUAVD syndrome.
Conclusion: Obtained results demonstrated high prevalence of common
CFTR mutations and 5T allele between Russian infertile men. Following
four mutations: F508del, CFTRdele2,3, W1282X and 2143delT,
are the commonest CFTR mutations in Russia.
P02.120
Prenatal diagnosis by ARms-PcR and genetic counseling in
couples of cFtR mutations carriers
L. A. Tamas 1 , Z. L. Popa 2 , L. Pop 3 , I. Popa 3 , G. Budau 2 , A. Anghel 1 , C. Samoila
1 , Z. Popa 4 , I. M. Ciuca 3 , C. Gug 5 ;
1 Department of Biochemistry, UMF, Timisoara, Romania, 2 Obstetrics and Gynecology
Clinic III, UMF, Timisoara, Romania, 3 Pediatric Clinic II, UMF, Timisoara,
Romania, 4 National Center of Cystic Fibrosis, Timisoara, Romania, 5 Department
of Genetics, UMF, Timisoara, Romania.
Objectives: The aim of this study was to provide a correct prenatal
diagnosis and genetic counseling for couples with previous family history
of cystic fibrosis who intended to have a new child.
Method and materials: 11 couples were selected for prenatal diagnosis,
based on family history or typical echographic findings. The couples
had previous children with cystic fibrosis who had been genetically
tested and had both mutations identified or had deceased children
diagnosed with cystic fibrosis but without molecular diagnostic. Genomic
DNA was isolated from amniotic fluid collected by transabdominal
amniocentesis in the 16th week of pregnancy and from venous
blood collected on EDTA from both parents. The genetic analysis for
CFTR mutations was performed with Elucigene CF29 kit which uses
the ARMS-PCR method. STR genotyping was performed for several
loci in order to verify the absence of contamination with maternal blood
or cells. When maternal contamination of amniotic fluid was unavoidable,
the culture of amniocytes in specific media was used for selection
of fetal cells.
Results: 4 heterozygous genotypes were identified (ΔF508/N, G542X/
N), six normal genotypes and one compound heterozygous genotype
(621+1G>T/ΔF508).
Conclusions: It is possible to perform prenatal diagnosis using Elucigene
CF29 kit in all cases with the exception of cases which can be
homozygous for non-ΔF508 mutations. STR genotyping and amniocytes
culture are complementary methods used in difficult cases for
obtaining a correct prenatal diagnosis.
P02.121
Prenatal diagnosis in cF Russian families
N. V. Petrova, E. E. Timkovskaya, T. A. Vasilyeva, R. A. Zinchenko;
Research Centre for Medical Genetics, Russian Academy of Medical Sciences,
Moscow, Russian Federation.
Cystic fibrosis is the most common recessive disease in Caucasians.
The spectrum and relative frequencies of mutations in the CFTR
gene significantly varied between different populations and ethnic
groups. According to our previous investigations 20 different CF mutations
(CFTRdele2,3(21kb), 394delTT, 604insA, L138ins, 621+1G>T,
R334W, R347P, F508del, 1677delTA, G542X, 2143delT, 2184insA,
K598ins, 3821delT, S1196X, 3677insTCAA, 3849+10kbC>T, W1282X,
3944delTG, N1303K) were accounted for 77% of CF alleles in Russian
patients with F508del (54,2%) and CFTRdele2,3(21kb) (7,2%) being
the most frequent ones. We have performed 123 prenatal diagnoses
for 98 couples. Two cases included twin pregnancies: one homozygous
and one heterozygous. 74 families with 17 different genotypes
were fully informative for direct DNA analysis performed by using multiplexPCR,
heteroduplex analysis and restriction analysis. In 19 families
only one parent mutant allele was known and in 5 families none of
CF mutations were identified, so prenatal analysis was done by indirect
DNA analysis using haplotype analysis of four dinucleotide repeats
(IVS1CA, IVS8CA, IVS17bCA, W30), one tetranucleotide repeat
(IVS6aGATT) and four biallelic restriction polymorphic sites. Materials
used for fetal DNA analysis were CVS samples. 30 fetuses were affected,
66 - heterozygous carriers and 28 were healthy with two normal
alleles of CFTR gene. In all cases when prenatal diagnosis indicated
that the fetus had CF the couples chose pregnancy termination.
P02.122
A new cryptic CFTR exon in mild cystic Fibrosis
C. Costa 1 , V. Prulière Escabasse 2 , L. Bassinet 3 , L. Golmard 1 , C. Gameiro 1 , A.
de Becdelièvre 1 , A. Coste 2 , M. Goossens 1 , E. Girodon 1 ;
1 Laboratoire de Génétique et INSERM U955 équipe 11, Creteil, France, 2 ORL
CHU H Mondor, Creteil, France, 3 Pneumologie-CRCM CHIC, Creteil, France.
Cystic fibrosis (CF) is the most frequent autosomal recessive disease
in the Caucasian population. So far, over 1500 CFTR gene mutations
have been described responsible for classical CF and CFTR-related
disorders. Screening for large gene rearrangements has improved
identification of CF alleles but a number of cases remain unsolved,
making genetic counselling difficult, particularly when the diagnosis
is uncertain. Unidentified CF mutations may lie in introns, such as
3849+10kbC>T and 1811+1.6kbA>G.
We report the case of a French 25y woman diagnosed with disseminated
bronchiectasis, pancreatic sufficiency and borderline sweat
tests. Screening of the 27 exons including search for gene rearrangements
only identified F508del in heterozygosity. Investigation at the
mRNA level was then performed from nasal epithelial cells.
An abnormal, longer CFTR mRNA was detected, corresponding to a
97bp insert between exons 6b and 7. This fragment matches a 101bp
sequence of intron 6b, and is flanked by the consensus donor and
acceptor splice sites. A new stop codon is created within the inserted
sequence. The amount of abnormal CFTR mRNA of the patient was
estimated to be 20% of the wild type, which suggests the abnormal
splicing is due to partial activation of a cryptic splice site. This hypothesis
is supported by the fact that the patient does not suffer from severe
CF. Studies at the genomic level are still ongoing to identify the
mutation which leads to partial activation of a cryptic splice site and
explains the creation of a new exon.