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2009 Vienna - European Society of Human Genetics

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Clinical genetics and Dysmorphology<br />

P02.123<br />

A synonymous mutation in the cFtR gene causes an aberrant<br />

splicing in an Italian patient affected by cystic fibrosis.<br />

V. Faa’ 1 , A. Coiana 2 , L. Costantino 3 , S. Pirroni 2 , M. Masala 2 , A. Cao 1 , M. Cristina<br />

Rosatelli 2 ;<br />

1 Istituto di Neurogenetica e Neur<strong>of</strong>armacologia, Consiglio Nazionale delle<br />

Ricerche, Cagliari, Italy, 2 Dipartimento di Scienze Biomediche e Biotecnologie,<br />

Universita’ degli Studi di Cagliari, Cagliari, Italy, 3 Policlinico Mangiagalli e Regina<br />

Elena, Milano, Milano, Italy.<br />

Genotype screening in human disease frequently identifies exon/ intron<br />

sequence variations whose association with the disease phenotype<br />

is unclear. In fact the pathologic effect <strong>of</strong> an apparently benign<br />

polymorphism, such as codon third position variations, or nucleotide<br />

change/ deletion in the intronic non canonical splicing regulatory elements,<br />

are difficult to assess.<br />

In this work we define the pathogenic role <strong>of</strong> a synonymous mutation<br />

found in an Italian patient affected by cystic fibrosis (CF). It consists<br />

<strong>of</strong> a G>T substitution at nucleotide 2811 on exon 15 <strong>of</strong> CFTR gene.<br />

CFTR mRNA analysis showed that this synonymous mutation created<br />

a new 5’ splice site inside exon 15 causing the skipping <strong>of</strong> 76 amino<br />

acids.<br />

Furthermore, CFTR mRNA analysis showed that, although this aberrant<br />

splicing caused a shorter exon 15, the downstream exonic sequence<br />

from exon 16 to the end <strong>of</strong> the ORF was in frame.<br />

Therefore, the skipping <strong>of</strong> amino acid residues included in exon 15,<br />

located in CFTR transmembrane domain MSD7, probably modify the<br />

structure and the regulation <strong>of</strong> the Cl- channel.<br />

The growing interest on the potential effects <strong>of</strong> single-nucleotide<br />

changes in coding and non-coding regions on the extent and accuracy<br />

<strong>of</strong> pre-mRNA splicing is expected to have a significant impact on the<br />

diagnosis and treatment <strong>of</strong> genetic diseases. The correct classification<br />

<strong>of</strong> mutations is essential to understand structure-function relationship<br />

in the corresponding protein, to assess the phenotypic risk in CF patients<br />

and to devise new therapies.<br />

P02.124<br />

Identification <strong>of</strong> a novel CFTR mutation in a patient with cystic<br />

fibrosis<br />

N. Polgar 1 , J. Bene 1 , K. Bolbas 2 , K. Pongracz 2 , K. Gyurkovits 2 , B. Melegh 1 ;<br />

1 Department <strong>of</strong> Medical <strong>Genetics</strong> and Child Development, University <strong>of</strong> Pecs,<br />

Pecs, Hungary, 2 Department <strong>of</strong> Pediatrics, Hospital for Chest Diseases <strong>of</strong> the<br />

Reformed Church <strong>of</strong> Hungary, Mosdos, Hungary.<br />

Cystic fibrosis (CF) is a most common autosomal recessive disease<br />

with a prevalence <strong>of</strong> 1 in 2500 and a carrier frequency <strong>of</strong> 1:22. CF<br />

is caused by mutations in the cystic fibrosis transmembrane conductance<br />

regulator (CFTR) gene expressed in several organs including<br />

the lung, the pancreas, and the sweat glands. So far 1604 mutations<br />

<strong>of</strong> the CFTR gene have been reported at the CF Mutation Database.<br />

We examined a 17-year-old girl, a daughter <strong>of</strong> a Hungarian mother<br />

and a Nigerian father with a tentative diagnosis <strong>of</strong> CF. The patient’s<br />

history was uneventful until her school years when mild upper respiratory<br />

infections appeared with repeated coughing periods and sweatchloride<br />

levels <strong>of</strong> 102mmol/l, however she did not have any intestinal<br />

symptoms. As direct sequencing <strong>of</strong> all 27 exons <strong>of</strong> CFTR revealed, the<br />

patient had two mutations in compound heterozygous form: a 2183<br />

AA>G frameshift mutation in exon 13, described previously in three<br />

unrelated CF patients <strong>of</strong> Sardinian descent; and a mutation not yet<br />

reported elsewhere, a 3872 G>A transition in exon 20 resulting in a<br />

glycine-glutamate amino acid change at position 1247. We found that<br />

the 2183 AA>G frameshift mutation was inherited from her Hungarian<br />

mother, while the 3872 G>A transition from her Nigerian father. The<br />

latter is also carried by her brother. This novel mutation affects an ATPbinding<br />

site <strong>of</strong> the CFTR protein, and was predicted to be probably<br />

damaging by the Poly-Phen prediction s<strong>of</strong>tware, thus we presume that<br />

it is a CF-mutation causing a milder, late-onset form <strong>of</strong> CF.<br />

P02.125<br />

Distribution <strong>of</strong> CFTR mutations in cystic fibrosis patients from<br />

Eastern Hungary<br />

I. Balogh1 , B. Nagy1 , F. Gonczi2 , E. Ajzner3 , E. Dzsudzsak1 , J. Kappelmayer1 ;<br />

1 2 University <strong>of</strong> Debrecen, Debrecen, Hungary, Kenezy Gyula Hospital, Debrecen,<br />

Hungary, 3Josa Andras Hospital, Nyiregyhaza, Hungary.<br />

Cystic fibrosis (CF) is the most common severe inherited monogenic<br />

disease in Caucasians. In addition <strong>of</strong> the most frequent deltaF508 mutation<br />

which is responsible for the 50-65% <strong>of</strong> the cases, more than<br />

1300 different rare mutations are present in the CFTR gene. Distribution<br />

<strong>of</strong> the different CFTR mutations show large ethnic variability. As<br />

an initial attempt to create a mutation testing panel in Hungary, the<br />

aim <strong>of</strong> this study was to determine which mutations are present among<br />

Eastern Hungarian CF patients.<br />

For the mutation analysis, 43 patients with severe CF phenotype were<br />

selected and tested with commercially available multiplex allele specific<br />

PCR and oligonucleotide ligation methods.<br />

Mutations in both alleles could be identified in 28 patients (65%). 19<br />

patients (44%) were homozygous for deltaF508, while the other 9 patients<br />

were compound heterozygous for two mutations. 4 out <strong>of</strong> them<br />

had deltaF508 and CFTRdele2,3(21kb), 2 had deltaF508 and N1303K<br />

and one patient had deltaF508 with c.1717-1G>A. The remaining two<br />

patients possessed two rare mutations (G542X with N1303K and<br />

G542X with R347P).<br />

In 12 patients (28%), only one mutation could be detected. 10 patients<br />

were heterozygous for delta F508, one patient had G542X and an other<br />

had N1303K in heterozygous form. In 3 patients (7%) no mutation<br />

was found.<br />

In conclusion, using multiplex mutation detection methods, the complete<br />

underlying genetic background could be identified in 65% <strong>of</strong> CF<br />

patients form Eastern Hungary, while in other 28%, one mutation was<br />

found. The frequency <strong>of</strong> CFTRdele2,3(21kb) mutation with Slavic origin<br />

was surprisingly high (9%).<br />

P02.126<br />

Cystic fibrosis liver disease and CFTR or MBL<br />

I. M. Ciuca1,2 , I. Popa1,2 , L. Pop1,2 , Z. Popa3 , L. Tamas4 ;<br />

1 2 3 Pediatric II Department, Timisoara, Romania, UMFT V.Babes, Romania, National<br />

Cystic Fibrosis Centre, Timisoara, Romania, 4Biochemistry Department,<br />

UMFT V Babes, Timisoara, Romania.<br />

Background: CFTR (cystic fibrosis transmembrane conductance regulator)<br />

gene and MBL (mannose binding lectine) gene seems to influence<br />

development <strong>of</strong> CF liver disease. Severe CFTR genotype and<br />

low serum MBL are promoting factor in development <strong>of</strong> CFLD. Study<br />

aim: assessment <strong>of</strong> CFLD patients in relation with genotype and MBL<br />

levels. Methods: Twenty five children with CFLD, followed in our National<br />

CF Centre were evaluated. Genotype results were taken from<br />

centre’s data base. MBL assay procedure was performed using MBL<br />

oligomer ELISA kit. Results: In patients with CFLD, 36% were MBL<br />

deficient; from those 66% Δ F508 homozygous, while in patients with<br />

normal or increase MBL 56% patients had “severe” genotype. Δ F508<br />

homozygous genotype was found in 43% CFLD patients, each other<br />

with a different genotype. Conclusions: A correlation between CFLD<br />

and specific genotype or MBL level could not be made. MBL2 genotyping<br />

is necessary to identify the patients predisposed to develop CFLD.<br />

Heterogeneity <strong>of</strong> genotypes in CFLD patients suggests the hypothesis<br />

<strong>of</strong> other factors in determination <strong>of</strong> cystic fibrosis associated liver disease.<br />

P02.127<br />

Abnormal ultrasound signs <strong>of</strong> fetal bowel in cystic fibrosis: a<br />

molecular approach.<br />

L. Porcaro 1 , L. Costantino 1 , V. Paracchini 1 , D. A. Coviello 1 , P. Capasso 1 , D.<br />

Degiorgio 1 , C. Colombo 2 , M. Seia 1 ;<br />

1 Fondazione IRCCS, Ospedale Maggiore Policlinico, Mangiagalli e Regina<br />

Elena, Milan, Italy, 2 CF Centre, Fondazione IRCCS, Ospedale Maggiore Policlinico,<br />

Mangiagalli e Regina Elena, Milan, Italy.<br />

Hyperechogenic fetal bowel (HFB), a possible prenatal sign <strong>of</strong> CF, is<br />

detected in 0.1−1.8% <strong>of</strong> pregnancies during the second or third trimester.<br />

The prevalence <strong>of</strong> meconium ileus (MI) is higher among neonates<br />

with previous HFB than in neonates with normal ultrasound imaging so<br />

there could be a relationship between HFB and MI.<br />

The aim was to evaluate usefulness and limits <strong>of</strong> genetic analysis in

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