2008 Barcelona - European Society of Human Genetics

Molecular and biochemical basis of disease
P06.177
sequence analysis of circadian clock modulators miR-132 and
miR-219 and their targets RFX4 and PHLPP in mood Disorder
Patients
E. Saus 1 , V. Soria 2 , F. Vivarelli 1 , J. M. Crespo 2,3 , J. M. Menchón 2,3 , M. Urretavizcaya
2,3 , X. Estivill 1,4 , M. Gratacòs 1 ;
1 CIBERESP (CIBER en Epidemiología y Salud Pública), Genes and Disease
Program and CeGen Barcelona Genotyping Node, Center for Genomic Regulation,
Barcelona, Catalonia, Spain, 2 Mood Disorders Clinical and Research Unit,
CIBER-SAM, Psychiatry Department, Bellvitge University Hospital, L’Hospitalet
de Llobregat, Barcelona, Catalonia, Spain, 3 Department of Clinical Sciences,
Bellvitge Campus, Barcelona University, Barcelona, Catalonia, Spain, 4 Experimental
and Health Sciences Department, Pompeu Fabra University, Barcelona,
Catalonia, Spain.
It has been widely supported that circadian rhythms are involved in the
pathophysiology of mood disorders (MD). Two brain-specific miRNAs
(microRNAs) have been recently reported as modulators of endogenous
circadian clock located in the suprachiasmatic nucleus in mice .
The authors have functionally characterized miR-132 and miR-219
within the context of circadian clock and gave experimental evidences
of genes Rfx4 and Phlpp as respective targets. We first explored the
conservation between species for both miRNAs and once the existence
of hsa-miR-132 and hsa-miR-219 was corroborated in humans,
we used different prediction programs to check the experimentally
supported target sites RFX4 and PHLPP in humans. Specifically, mi-
Randa predicted hsa-miR-132 to target RFX4 and TargetScan predicted
PHLPP as a target site for hsa-miR-219, consistent with previous
work in mice . Once both miRNAs with their respective target sites
were confirmed in humans, we questioned whether these two miRNAs
and their target genes RFX4 and PHLPP are altered in mood disorder
patients . Thus, we re-sequenced both miRNAs and their respective
target sites at RFX4 and PHLPP genes in a sample consisting of 365
unrelated patients (218 Unipolar Major Depressive Disorder and 147
Bipolar Disorder) diagnosed according to DSM-IV criteria . All patients
completed the Spanish versions of the Seasonal Pattern Assessment
Questionnaire and the Horne-Östberg Morningness-Eveningness
Questionnaire. This is the first time that the circadian clock regulation
by miRNAs is explored in mood disorder, representing a first step to
elucidate the underlying mechanism of these proteins and the role of
these miRNAs in mood disorders .
P06.178
Allelic frequencies and heterozygosities of microsatellite
markers covering the whole genome in the Korean
J. Lee, M. Park, K. Kim, H. Lee, K. Kim, J. Jung, B. Oh, H. Kim;
Center for Genome Science, National Institute of Health, Seoul, Republic of
Korea.
Microsatellite markers are an essential tool for genetic linkage analysis
because of their high polymorphism content . Four hundred commercially
available markers covering the entire genome were genotyped
from 578 sib individuals from 249 Korean families . Allelic frequencies
and heterozygosities were determined for each marker loci and compared
between Korean, Taiwanese, Japanese and Caucasian populations
. In the three Asian populations, 10-13% of the markers had less
than 0 .6 heterozygosity, whereas in the Caucasian population, only
0 .5% of the markers had less than 0 .6 heterozygosity . Mean identical
by descent (IBD) values were calculated for 578 sib individuals .Analysis
of IBD values greater than 0 .5 suggested that markers with low
heterozygosity can also provide positive linkages, at least for the IBD
sharing method of model-free linkage analysis . The data presented in
this study will be a useful reference for genome-wide screens of Koreans
and comparative studies with other ethnic populations .
P06.179
Association study of migraine and 19 candidate genes involved
in serotoninergic neurotransmission in a spanish population
R. Corominas 1 , M. J. Sobrido 2,3 , E. Cuenca-León 1 , P. Blanco 4,3 , B. Narberhaus
5 , M. Del Toro 1 , R. Leira 6 , J. López 6 , M. Ribasés 1 , A. Macaya 1 , B. Cormand
7,3 ;
1 Hospital Universitari Vall d’Hebron, Barcelona, Spain, 2 Fundación Pública
Galera de Medicina Xenómica, Santiago de Compostela, Spain, 3 CIBER Enfermedades
Raras, Instituto de Salud Carlos III, Barcelona, Spain, 4 Grupo de
Medicina Xenómica, Universidad de Santiago de Compostela, Santiago de
Compostela, Spain, 5Hospital General de Manresa, Manresa, Spain, 6Servicio de Neurología, Hospital Clínco de Santiago, Santiago de Compostela, Spain,
7Departament de Genètica, Facultat de Biologia, Universitat de Barcelona,
Barcelona, Spain.
Migraine is a common neurological disorder with a complex inheritance
pattern . Although the pathophysiology of the disease is not well
understood, several studies suggest that serotonin-related genes may
participate in its pathogenesis . The involvement of some of these
genes has been studied in different migraine populations with conflicting
results thus far .
In the present study we aimed to evaluate the possible role of 19 genes
involved in serotoninergic neurotransmission in the susceptibility to migraine
in a Spanish population using a case-control approach based
on SNPs . A total sample of 528 unrelated patients were recruited and
diagnosed following the IInd International Criteria of Headache Disorders
from the IHS (308 patients had migraine without aura and 220
had migraine with aura) and compared to 528 sex-matched controls
in which migraine was ruled out . All individuals were Spanish of Caucasoid
origin from Catalonia and Galicia . SNP selection was based
on genetic coverage parameters and genotyping was performed using
SNPlex technology . Chi-square tests were used for the comparison
of allele and genotype frequencies between the patient and control
groups for each single SNP . Preliminary data of nominal associations
suggest a contribution of HTR1E, HTR2B, HTR3B, MAOA and DDC in
the genetic predisposition to migraine .
P06.180
Genetic diagnosis of Ataxia telangectasia and role of
mitochondria on it
M. Houshmand;
NIGEB, Tehran, Islamic Republic of Iran.
Ataxia telangiectasia (AT) is an autosomal recessive disorder in
1/40,000 to 1/100,000 in reported populations . There is a 25% possibility
for having an affected child when parents are carrier for the
ATM gene mutation . There is no cure available for this disease and
prenatal testing is strongly recommended for prevention of this disease
. Although the preferred method is the direct mutation analysis of
the ATM gene, the large size of the ATM gene with 63 exons and the
large number of possible mutations in patients considerably limit efficiency
of mutation analysis as a diagnostic choice. In this study, four
molecular markers: D11S2179, D11S1787, D11S535, D11S1343 are
genotyped in 19 unrelated families from different regions of Iran . All
carriers and affected patients were diagnosed accurately . This method
is effectively useful in prenatal diagnosis of AT .
We also investigated mt-DNA deletions and haplogroups in AT patients .
In this study, 24 Iranian patients suffering from AT and 100 normal
controls were examined . mt-DNA was extracted from whole blood and
examined by 6 primers for existence of mitochondrial deletions . We
also amplified and sequenced the mtDNA HVS-I by standard sequencing
techniques . mtDNA deletions were observed in 54 .1% (13/24) of
patients (8 .9 kb deletion in all samples, 5 .0 kb in one and 7 .5 kb in two
patients), representing mtDNA damage which may be due to oxidative
stress in mitochondria . Our results showed that there is no association
between mtDNA haplogroups and AT . This data may indicate involvement
of mitochondrial damage in the pathogenesis of AT .
P06.181
Role of mitochondria in Friedreich Ataxia
M. Houshmand;
NiGEB, Tehran, Islamic Republic of Iran.
Friedreich’s Ataxia (FA) is the commonest genetic cause of ataxia
and is associated with the expansion of a GAA repeat in intron 1 of
the frataxin gene . Mitochondrial DNA (mtDNA) could be considered a
candidate modifier factor for FA disease, since mitochondrial oxidative
stress is thought to be involved in the pathogenesis of this disease . The
expansion (GAA) repeat in the first intron causes decreased frataxin
expression by interfering with transcription .: Activity of mitochondrial
respiratory chain complex I (measured as NADH ferricyanide reductase)
and intracellular ATP measurement was performed on lymphocyte
of FA patients (n =12) and control subjects (n =25) . Common deletion
were identified and confirmed by southern blotting in FA patients.
Homozygous GAA expansion was found in 21 (84%) of all cases . In
four cases (16%), no expansion was observed, ruling out the diagnosis