2008 Barcelona - European Society of Human Genetics

Normal variation, population genetics, genetic epidemiology 0
forms - 1:1600 . The most frequently autosomal dominant diseases
were Ehlers-Danlos’ syndrome -1:6400, Marfan’s syndrome - 1:20000,
idiopathic scoliosis - 1:20000, polydactylia postaxialis - 1:21400, syndactyly,
type I - 1:26700, osteogenesis imperfecta - 1:32000 . In autosomal
recessive, it was Spondiloepiphysial dysplasia Tarda - 1:64200,
Spondiloepiphysial dysplasia with mental retardation - 1:80200, Langer
type mesomelic dysplasia - 1:107000 . In X-linked, it was Aarskog syndrome
- 1:53500, Coffin-Lowry syndrome - 1:53500, Proud syndrome
- 1:80200 . Therefore, our research is enabling to improve genetic consultation’s
activity, directed to decrease of hereditary disease’s pressure
in Rostov region of Russian Federation .
P07.116
smith-Lemli-Opitz syndrome mutations in recurrent miscarriage
E. Dimitriadou 1 , I. Lalou 1 , S. Kalantaridou 2 , M. Pavlou 2 , A. Sotiriadis 2 , M. Tzoufi
3 , I. Georgiou 2 , M. Witsch-Baumgartner 4 , M. Syrrou 1 ;
1 Genetics Unit, Laboratory of General Biology, Medical School, University of
Ioannina, Ioannina, Greece, 2 Department of Obstetrics and Gynaecology, Medical
School, University of Ioannina, Ioannina, Greece, 3 Child Health Department,
Medical School, University of Ioannina, Ioannina, Greece, 4 Department for
Medical Genetics, Molecular and Clinical Pharmacology, Innsbruck, Austria.
Recurrent miscarriage (RM) is defined as >3 (or >2) consecutive pregnancy
losses before 20 weeks of gestation and affects 1-3% of all
women . More than 40% of RM are of unknown etiology and assumed
to be genetic in origin .
Smith-Lemli-Opitz Syndrome (SLOS, MIM270400) is an autosomal
recessive disorder of cholesterol biosynthesis caused by mutations in
the gene DHCR7 . The prevalence of SLOS ranges between 1:15000
and 1:60000 in European populations, but there is a discrepancy between
expected and observed incidence of SLOS mutations that might
be in part explained by first trimester miscarriages of affected fetuses.
Aim: 1 .To compare the prevalence of common SLOS mutations in
Greek women with unexplained RM and in a control group . 2 . To
correlate common SLOS mutations with RM in order to conclude if
screening for common SLOS mutations in couples with >2 spontaneous
miscarriages should be added in the evaluation of RM .
Study group: 124 women aged 2 consecutive first trimester
miscarriages . Controls: 75 healthy age-matched women, with
proven fertility . The three most common for the Greek population mutations
of the DHCR7 gene (IVS8-1G>C, p .Trp151X and p .Thr93Met)
were studied using allele-specific PCR.
Two out of 124 women with unexplained RM were heterozygous for
null IVS8-1G>C mutation . No carriers were found among the control
group . This is an ongoing study .
P07.117
Prevalence of functional sNPs in candidate genes for common
diseases in four siberian populations
M. V. Golubenko1 , M. S. Nazarenko1 , A. N. Kucher1 , E. Y. Bragina1 , N. P.
Babushkina1 , I. A. Goncharova1 , V. V. Pogrebenkova1 , O. Y. Bychkova1 , O. G.
Ivanova1 , T. V. Zheykova1 , I. V. Saltykova2 , A. R. Simakina2 , L. A. Koneva1 , S. V.
Buikin1 , O. A. Makeeva1 , V. P. Puzyrev1,2 ;
1 2 Institute for Medical Genetics, Tomsk, Russian Federation, Siberian State
Medical University, Tomsk, Russian Federation.
Genetics of common diseases deals with common polymorphisms (in
most cases SNPs) . There are differences in the common diseases
prevalence between human populations which may be explained in
part by variation in frequencies of some predisposing SNPs depending
on population descent . Furthermore, linkage disequilibrium is also
known to be different in diverse populations . We studied twelve known
candidate genes for common diseases of cardiovascular and immune
systems, in four Siberian populations of different ethnic origin, namely
Tuvinians, Yakuts, Buryats, and Russians (384 individuals in total) .
ACE, AGTR1, NOS3, GNB3, TNF and LTA, TNFRSF1A, ADRB2, IL4,
IL4RA, IL12A, IL12B, IL12RB1 genes were studied . Few SNPs in each
gene were picked for genotyping on the basis of known associations
with common diseases and/or possible functional effect . We have
found significant differences between populations in both frequencies
and LD estimates for most of genotyped SNPs . Few SNP positions
were not polymorphic in our samples. We confirmed the fact that some
SNPs within ACE, NOS3, TNF, IL4RA genes are in strong linkage
disequilibrium. Taking into account that significant differences were
found between related populations of Asian origin, as well as between
Russians and other European populations, our results emphasize
need for further investigations of prevalence of candidate SNPs for
common diseases in different populations . Differences in functional
SNPs frequencies suggest population specific character of genetic
structure of predisposition to common diseases which should be taken
into account during development of genetic tests for common diseases
predisposition in different regions .
P07.118
Application of mLPA in multiplex sNP genotyping for genetic
epidemiology
C. Brasch-Andersen 1,2 , L. Christiansen 3,2 ;
1 Clinical Pharmacology, Institute of Public Health, University of Southern Denmark,
Odense, Denmark, 2 Dept. of Biochemistry, Pharmacology and Genetics,
Odense University Hospital, Odense, Denmark, 3 Epidemiology, Institute of
Public Health, University of Southern Denmark, Odense, Denmark.
A method for simple and cost-effective medium-scale genotyping in
large epidemiological studies is often needed, for instance when investigating
the entire genetic variation in a single or a few genes .
The multiplex ligation-dependent probe amplification assay (MLPA)
was initially developed for detection of DNA deletions or duplications,
but is also suitable for genotyping single point polymorhisms (SNPs) .
We designed an allele discrimination assay for simultaneous genotyping
of at least 10-20 SNPs in a large number of samples using the
MLPA technology . Based on the MLPA probe design protocol we constructed
3 probes per SNP: 2 allele specific and 1 locus specific, which
after ligation were PCR amplified and size-separated using capillary
electrophoresis. In addition to the template specific sequence each of
the MLPA probes contain a variable length stuffer sequence enabling
both SNPs and alleles to be discriminated by size, and a primer specific
sequence common to all probes, thus permitting multiplex PCR
using only one primer set .
We applied the method on two genes for which the genetic variation
was covered by 12 and 19 tagging SNPs, respectively . Genotyping
results were verified using CEPH controls with known genotypes.
Applying the MLPA method will enable most labs to genotype SNPs in
a medium scale without investing in new lab equipment as the method
only requires a PCR machine and a capillary electrophoresis system .
P07.119
Large scale screening for spinal muscular atrophy (smA) - effect
of ethnicity on frequency of exon 7 deletion v.s duplication
R. Sukenik-Halevy 1,2 , R. Pesso 3 , N. Garbian 3 , N. Magal 1,2 , M. Shohat 1,2,3 ;
1 Recanati Institute of Medical Genetics, Petach Tikva, Israel, 2 Rabin Medical
Center, Petach Tikva, Israel, 3 Maccabi Health Insurance Genetic Institutes,
Rehovot, Israel.
Approximately 95% of SMA patients have homozygous deletions of
exon 7 and/or 8 of the SMN1 gene and 5% are compound for deletion
of exon 7 and a point mutation . The carrier frequency varies between
1:150 and 1:35 .
We undertook a survey to assess the carrier rate among healthy individuals
with no family history, evaluate the false negative rate (individuals
with three copies of exon 7), and determine any ethnic differences
.
We analysed data from two medical centres in Israel that conduct carrier
screening among the normal population using the MLPA kit . We
studied the copy number of exons 7 and 8 and divided the subjects into
six ethnic groups: Ashkenazi, North African, Iranian/Iraqi, Yemenite,
Balkan, other Jewish . Statistical analysis was performed using chisquare
.
Between February-October 2007, 7308 subjects were tested in Maccabi
clinics and 1729 at Rabin Medical Center . The carrier rate (deletion
of exon 7) was 1:62 and was not statistically different among the
various ethnic groups .
Duplication of exon 7 was found in 1 in 9 individuals - a false negative
rate of 5.5%. There was a significant difference between the ethnic
groups: 12% among Ashkenazim, 4 .4% among North African Jews
and 6%-8% in other groups (p