2008 Barcelona - European Society of Human Genetics

Molecular and biochemical basis of disease
operative Research Centre, Sydney, Australia, 3 Vision Cooperative Research
Centre, Syndey, Australia.
Myopia (short sightedness) is a complex trait influenced by both genetic
and environmental factors. To date, fifteen myopia susceptibility
loci (MYP1-15) have been identified but no definitive gene pinpointed.
This study reports the identification of a novel locus for myopia located
on chromosome 2q37 adjacent to, but not overlapping, MYP12 . Three
large multigenerational families with autosomal dominant myopia were
recruited into this study . These families consist of 49 participants (35
affected) each of which has undergone a comprehensive ophthalmic
examination . Individuals with other eye diseases that may affect vision
such as glaucoma and keratoconus have been excluded . A genomewide
scan was performed using 400 microsatellite markers spaced an
average of 10 cM apart . Using MERLIN, a multipoint parametric LOD
score of 2 .37 was calculated on chromosome 2q37 . This LOD score
increased to 3 .43 with nonparametric analysis . The 1 LOD support interval
initially suggested that this region may overlap with a known
myopia susceptibility locus, MYP12. However, further fine mapping
and haplotype analysis narrowed down the critical region to a 0 .8cM
region that no longer overlaps MYP12 . Hence, a novel locus for myopia
was identified on chromosome 2q37 between markers D2S1397
and D2S2968 . Sequencing of all known and hypothetical genes in the
region is underway in order to identify DNA sequence variants associated
with myopia .
P06.200
Rapid Analysis of myotonic Dystrophy 1 using Quantitative
Fluorescent and Long PcR
M. Skrzypczak, S. Schinkel, A. Gross, U. G. Froster;
Institute of Human Genetics, University of Leipzig, Leipzig, Germany.
Diagnostics of myotonic dystrophy 1 (DM1) are based on the identification
and determination of CTG repeat expansion in the DMPK-gene .
This is usually done by Southern blot analysis - a time consuming and
very laborious technique requiring high molecular weight DNA . Our
study aimed at developing a highly sensitive, rapid and economical
molecular analysis characterizing the CTG repeat region of DMPKgene
based on a two step PCR protocol . Therefore we analyzed 105
patients with the clinical diagnosis of myotonic dystrophy 1 derived
from the DNA bank of the Institute of Human Genetics, University of
Leipzig (Germany) who had already been tested by Southern blot
analysis . 60 patients had one normal and one mutated allele of up to
2700 CTG repeats . 12 probands were homozygous for normal CTG
repeat length . In the remainder (33 patients) two different normal alleles
of up to 37 CTG repeats were present . Firstly, for the detection of
alleles of up to 100 repeats quantitative fluorescent (QF) amplification
with primers flanking the repeat region and 2 reference genes for standardization
were used . With these methods it was possible to identify
both homozygous and heterozygous DM1 alleles . Secondly, long PCR
was just performed if a single wild type allele was detected by giving a
QF-PCR-signal only half as intense . The results of using QF and long
PCR indicate high accuracy in comparison to Southern blot analysis .
We conclude that our new rapid analysis is reliable for genetic testing
of DM1 patients .
P06.201
A case of nail patella syndrome with severe renal involvement in
two sisters
J. Reiterová1 , J. Štekrová2 , M. Urbanová2 , M. Merta1 ;
1 2 Department of Nephrology, Prague, Czech Republic, Institute of Biology and
Medical Genetics, Prague, Czech Republic.
Nail-patella syndrome (NPS) is characterized by developmental defects
of dorsal limb structures, nephropathy, normal tension glaucoma
and sensorineural hearing impairment . NPS is a rare disorder with autosomal
dominant mode of inheritance and is caused by heterozygous
mutations in the transcription factor LMX1B . Proteinuria was described
in 21% of individuals with NPS . Nevertheless, renal failure in a rare
event .
A 38-year-old woman was admitted to our nephrology unit because of
severe nephrotic syndrome . The diagnosis of NPS was established
because of fingernail dysplasia, hypoplastic patellae, iliac horns and
dislocation of the radial head . She underwent renal biopsy with the
finding of proliferative glomerulonephritis at the age of 7 years. Her
sister with NPS suffered under severe nephrotic syndrome and renal
insufficiency which lead to renal failure at the age of 13 years. Her
father with NPS suffers only under mild proteinuria at the of 70 years .
All 8 exons of the LMX1B gene were amplified by polymerase chain
reaction with described primers and then sequenced on an automatic
fluorescent sequencer.
The missense mutation in exon 4 (c .599 G>A, p .Arg200Gln) of the
homeodomain of the LMX1B gene was detected . This mutation was
detected in the examined patient with renal failure as well as in her father
with mild renal involvement . This missense mutation was already
described in more families with NPS but only in individuals without proteinuria
. The patient is nowadays dependent on peritoneal dialysis .
To conclude, we describe a case of NPS with severe renal involvement
.
Supported by project VZMSMT 0021620806
P06.202
serum levels of some igG and igm type natural autoantibodies
are differently regulated in carriers and non-carriers of HLA-
DR16
G. Füst 1 , É. Pozsonyi 2 , B. György 3 , T. Berki 4 , Z. Bánlaki 1 , E. Buzás 3 , K. Rajczy 2 ,
Z. Prohászka 1 , Á. Szilágyi 1 ;
1 3rd Dept Intern Med, Budapest, Hungary, 2 National Blood Transfusion Service,
Budapest, Hungary, 3 Institute of Genetics, Immunobiology and Cell Biology,
Semmelweis University, Budapest, Hungary, 4 Department of Immunology and
Biotechnology, Pécs University, Pécs, Hungary.
Natural autoantibodies (IgM or IgG type autoantibodies (Abs) present
in the sera of most healthy individuals) are most important participants
of the immune response . Little is known, however, on the
genetic regulation of their plasma levels in human beings . Therefore
we determined the concentrations of the IgM and IgG type antibodies
against certain conserved self antigens (60 kD heat shock proteins
(hsp60), citrate synthase (CITS) , and chondroitine sulphate (CONS)
in the sera of 78 healthy individuals out of a family study with known
alleles of several polymorphisms in the class I, class III and class II
regions of main histocompatibility complex (MHC, HLA in humans) . We
found significantly lower serum levels of the IgM type CITS (p=0.029)
and COTS (p=0 .026) Abs in the carriers than non-carriers of the HLA-
DR16 allele . Even stronger differences were found when levels of two
Abs were considered. Frequency of the DR16 alleles were significantly
higher in subjects with 1 or 2 low (in the lowest quartile) CITS/COTS
Abs (p=0 .002), CITS-hsp60 Abs (p=0 .001) and COTS/hsp60 Abs
(p=0 .003) as compared to those with normal Ab titers for both antigens
. Abs against these antigens exhibited strong positive correlation
(p=0 .01) By contrast, concentrations of IgG type anti-hsp60 Abs was
siginificantly higher (P=0.008) in the carriers than non-carriers of the
HLA-DR16 allele . Similar differences were found when carriers and
non-carriers of the HLA-DR16-DQ5 haplotype were considered . These
novel observations indicate that not only induced, acquired but natural,
inborn immune resoponse as well is regulated by the MHC .
P06.203
cytokine (tNF-alpha, tGF-beta1, iL-10, iFN-gamma, iL-6)
genotyping in turkish children with nephrotic syndrome: A brief
report
S. Pehlivan 1 , K. Ozdilli 2 , T. Sever 1 , Y. Duvarcı 3 , M. Buyukcelik 4 , F. Savran-
Oguz 3 , S. Oguzkan Balci 1 , M. Carin 3 , A. Balat 4 ;
1 University of Gaziantep, Faculty of Medicine, Department of Medical Biology,
Gaziantep, Turkey, 2 Halıc University, Institute of Health Science, Istanbul, Turkey,
3 Istanbul University, Faculty of Medicine, Department of Medical Biology,
Istanbul, Turkey, 4 University of Gaziantep, Faculty of Medicine, Department of
Pediatric Nephrology, Gaziantep, Turkey.
Considering the recognized influence of cytokines in nephrotic syndrome
(NS) development, the aim of this study was to investigate
whether this disease may be associated with polymorphisms of the
IL-6, IL-10, IFN-gamma, TGF-beta1 and TNF-alpha genes .
Forty-six children with NS, and 46 age-and sex-matched healthy controls
were tested for 8 polymorphisms in 5 different genes . DNA was
extracted from whole blood by standard salting out method . Cytokine
genotyping was performed by polymerase chain reaction sequencespecific
primer methods. The polymorphisms analyzed in the present
study were IL-6 (-174 G/C), IL-10 (-1082 A/G, -819 T/C, -592 C/A),
IFN-gamma (+874 A/T), TGF-beta1 (+10 T/C; +25 C/G) and TNF-alpha
(-308 G/A) .