2008 Barcelona - European Society of Human Genetics

Molecular and biochemical basis of disease
to 0 .00008) . The strongest signals emerged from the haploblock harboring
the trait-associated STR .
These data provide further evidence for involvement of RELN gene
variations in cognitive functions .
P06.252
the risk of respiratory distress syndrome in neonates from
Bashkortostan, Russia and gene polymorphisms of cytochrome
P450 (CYP A , CYP A ) and glutathione-s-transferase M
(GSTM )
L. Khamidullina1 , K. Danilko2 , R. Fayzullina2 , T. Victorova1 ;
1 2 Institute of Biochemistry and Genetics, Ufa, Russian Federation, Bashkortostan
State Medical University, Ufa, Russian Federation.
We have investigated association between polymorphisms of cytochrome
P450 genes (CYP1A1 (A2455G, T3801C), CYP1A2 (A-163C,
T-2467delT)), glutathione-S-transferase M1 (deletion GSTM1) and risk
of developing respiratory distress syndrome (RDS) in neonates from
Bashkortostan .
After birth molecular oxygen and free radicals influence on the neonates
lung . They are potentially harmful to cellular components . Antioxidants
provide protection against oxidative damage to proteins,
lipids and DNA .
We used whole peripheral blood of 144 patients with RDS and umbilical
cord blood of 217 healthy term neonates for the isolation of genomic
DNA. It was used PCR amplification. We used chi-square tests to detect
the association between genes polymorphisms and RDS babies .
It was shown that the CYP1A1 (T3801C) gene genotypes frequency
distribution patterns not significantly differ between patients with RDS
and healthy neonates (χ2 =1 .92, df=2, P=0 .382) . In male infants the
CYP1A1 TC genotype was associated with higher risk of RDS (38 .1%
in patients vs. 20.5% in healthy babies; χ2 =6 .8, P=0 .009; OR=2 .39,
95%CI 1 .23-4 .68) . While, the CYP1A1 TT genotype had a protective
effect (60.7% vs. 78.7%; χ2 =7 .0 P=0 .009; OR=0 .41, 95%CI 0 .22-
0 .81) .
But at the same time we found no differences in the genotypes frequency
distributions of the CYP1A1(A2455G), CYP1A2 genes within
the patients and healthy groups .
We also didn’t find any association of GSTM1 gene with RDS .
Our results showed that the polymorphisms in CYP1A1 may play a
significant role in the development of RDS in male neonates.
P06.253
Genetic diagnosis of autosomal dominant and recessive
Retinitis Pigmentosa using sNP high-throughput genotyping
E. Pomares 1,2 , G. Marfany 1,3 , R. Gonzàlez-Duarte 1,2 ;
1 Dept. de Genètica. Universitat de Barcelona, Barcelona, Spain, 2 CIBERER.
Instituto de Salud Carlos III, Barcelona, Spain, 3 IBUB. Universitat de Barcelona,
Barcelona, Spain.
Retinitis Pigmentosa (RP), the major cause for blindness in the adults,
is an extremely heterogeneous monogenic disorder which shows all
mendelian types of inheritance . Up to now, more than 30 RP genes
have been described, 17 of which are involved in autosomal dominant
(adRP) and 20 in autosomal recessive (arRP) forms . However, many
cases remain unassigned . Proper genetic diagnosis of the patients
and potential carriers requires screening of all the candidates, but the
high number of genes, with no major mutation sites, makes conventional
mutation analysis time-consuming and costly for a small/medium
sized laboratory . In addition, before undertaking the search for new
RP genes, the already known candidates have to be ruled out . Taking
into account these data and the fact that there is increasing evidence
assigning the same candidate genes as responsible for distinct
retinal dystrophies, we have designed an innovative time-cost effective
strategy for cosegregation analysis of 39 RP and LCA genes by SNP
genotyping on isolated families . This high-throughput strategy allows
to discard the genes that do not cosegregate with the disease and
highlights the remaining candidates . Subsequent mutational screening
has allowed us to identify the causative mutations for several families .
This type of analysis is very powerful in the arRP forms, particularly
when the family is consanguineous . For adRP families, the analysis of
several affected siblings is usually informative enough to discard most
of the candidates . This approach can also be successfully applied to
diseases with high genetic heterogeneity .
P06.254
Genomewide Linkage validation of the RP locus and
molecular Evaluation of Forty three candidate Genes
J. Pieras 1,2 , M. Abd El-Aziz 3 , I. Barragan 1,2 , C. O’Driscoll 3 , S. Borrego 1,2 , L. Abu
Safieh 3 , M. El-Ashry 3 , N. Carter 4 , C. Ponting 5 , S. Bhattacharya 3 , G. Antiñolo 1,2 ;
1 Unidad de gestión Clínica de Genética, Reproducción y Medicina Fetal, Hospitales
Universitarios Virgen del Rocío, Sevilla, Spain, 2 Centro de Investigación
Biomédica en Red de Enfermedades Raras (CIBERER), ISCIII, Seville, Spain,
3 Department of Molecular Genetics, Institute of Ophthalmology, London, United
Kingdom, 4 The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus,
Hinxton, Cambridge, United Kingdom, 5 The Medical Research Council
Functional Genetics Unit, Department of Physiology, Anatomy and Genetics,
University of Oxford, Oxford, United Kingdom.
RP25locus (Chr.6:56.02-89.78Mb) was identified as the genetic cause
in 14% of autosomal recessive Retinitis Pigmentosa (RP) in Spain .
Linkage analysis has also reported the presence of this locus in Pakistani
and Chinese families .
Our objective was: to confirm the initial findings of linkage to RP25locus
by genomewide linkage analysis; mutation screening of genes from
the RP25 region in 6 Spanish families with autosomal recessive RP
(arRP) linked to this locus; analysis of new arRP families by microsatellite
markers spanning the chromosome 6p12 .1q15 .
The data obtained using the 10KGeneChip-Mapping array have confirmed
the original evidence of linkage to only the RP25locus in the
three families with no linkage to any other region in the genome . Targeted
linkage analysis of 18 newly ascertained arRP families led to
the identification of five additional Spanish families also linked to RP-
25locus .
Bioinformatics analysis of the RP25 region indicated in excess of 111
genes with many showing retinal expression . 43 candidate genes were
selected on the basis of their function, tissue expression pattern and/or
the genetic data .
The direct sequence analysis from these genes (38,7%) led to the
identification of 244 Single Nucleotide Polymorphisms, of which 76
were novel .
In conclusion, the fact that none of the observed variants were pathogenic
exclude the screened genes as disease causing in these families
. However, we could not rule out these genes as good candidates
for other retinal degenerations mapping to the same chromosomal
region .
These results support and validate the high prevalence of RP25 in the
Spanish population .
P06.255
Retinoblastoma and microdeletion syndrome: identification of
PcDH8 as a candidate for developmental delay
C. Dehainault1 , D. Michaux1 , L. Castera1 , I. Aerts1 , L. Desjardins1 , D. Stoppa-
Lyonnet1,2 , M. Gauthier-Villars1 , C. Houdayer1,3 ;
1 2 Institut Curie, Paris, France, INSERM U830 Université Paris Descartes, Paris,
France, 3UMR INSERM 745 Université Paris Descartes, Paris, France.
Retinoblastoma (RB), the most common pediatric intraocular neoplasm,
results from inactivation of both alleles of the RB1 gene, located
in 13q14 .2 . Whole germline RB1 gene deletions represent 6
% of RB1 mutational spectrum . When the deletion involves the RB1
flanking regions it also causes a variable degree of mental retardation
and several dysmorphic abnormalities .
In order to refine the role of chromosomal regions adjacent to RB1 in
mental retardation and developmental delay, we decided to map the
breakpoints in seven RB patients harbouring a whole gene deletion .
Five of these patients presented no associated clinical abnormality,
one presented a mild developmental delay with epileptic seizures, and
one presented developmental delay with facial dysmorphism .
To precisely map the deletion breakpoints we designed a 385 000 oligos-custom
array (Nimblegen) focusing on RB1 and its flanking regions
(34-74Mb) . We also used MP/LC, a multiplex semi quantitative
PCR assay running on a DHPLC platform to further narrow the breakpoint
regions . Then PCRs spanning the breakpoints were performed
and sequenced which allowed the deletion breakpoints to be defined
at the nucleotide level .
We compared the deleted intervals between RB-only patients and RB
patients with developmental delay and define a 3Mb critical interval
that includes a good candidate, protocadherin 8 (PCDH8) . PCDH8 is
thought to function in signalling pathways and cell adhesion in a cen-