2009 Vienna - European Society of Human Genetics

Molecular basis of Mendelian disorders
Italy, 2 Institute of Dermatological Sciences, Fondazione Ospedale Maggiore
Policlinico, Mangiagalli, Regina Elena, IRCCS, Milano, Italy, 3 Institute of Dermatological
Sciences, University of Brescia, and Azienda Ospedaliera Spedali
Civili, Brescia, Italy, 4 U.O. Genetica Medica, Policlinico Sant’Orsola Malpighi,
University of Bologna, Bologna, Italy, 5 UOC Malattie del Ricambio, Dipartimento
di Medicina Interna e Dermatologia, Università Cattolica del Sacro Cuore,
Roma, Italy, 6 Emergency Medicine Department, S. Maria degli Angeli General
Hospital, Pordenone, Italy, 7 Dipartimento di Pediatria, Università di Padova,
Padova, Italy, 8 Dipartimento di Biochimica A. Castellani, Università di Pavia,
Pavia, Italy.
Vascular EDS (vEDS) (MIM #130050) is a dominantly inherited disorder,
whose clinical diagnosis is made by major and minor criteria
(e.g., easy bruising, thin skin, typical facies, and fragility of arteries, or
internal organs). The first major complication occurs in 25% of vEDS
patients by the age of 20, and in 80% by the age of 40; the median
survival is 48 years. vEDS is due to mutations in COL3A1 gene. About
200 COL3A1 mutations have been reported. Mutations in TGFBR1
and TGFBR2 cause the Loeys-Dietz syndrome (LDS) type II (MIM
#610380), presenting with vEDS major signs and without cardinal features
of originally described LDS.
In this work we report the characterization of Italian vEDS patients. In
17 out of 32 probands, with presumed vEDS, we disclosed 15 novel
and 2 known COL3A1 mutations: 13 (76,5%) missense, and 4 (23.5%)
splicing mutations. All the missense mutations affected a glycine in
the collagenous domain of the protein, and all the splicing mutations
the donor splice site, leading to exon in frame skipping. No TGFBR1
and TGFBR2 mutations were detected in COL3A1 negative patients.
The median age of the first complication in 15 out 17 probands was
28.5 years. Two probands (at 35 and 12 years) and 3 relatives died for
abdominal aorta rupture. The most involved vessels were the mediumsizes
arteries, mostly the splenic and hepatic ones. The majority of the
patients were diagnosed after a major event. These data add insights
to the knowledge of vEDS genotype-phenotype correlation.
P12.164
The influence of VEGF polymorphism on the progression of
chronic glomerulonephritis
H. Šafránková 1 , J. Reiterová 1,2 , M. Merta 2,1 , J. Štekrová 2 , V. Tesař 1 ;
1 Dept. of Nephrology, 1st Faculty of Medicine of Charles University and General
Faculty Hospital, Prague, Czech Republic, 2 Institute of Biology and Human
Genetics, 1st Faculty of Medicine of Charles University and General Faculty
Hospital, Prague, Czech Republic.
The role of vascular endothelial growth factor (VEGF), a potent angiogenic
agent, in the pathogenesis of different glomerulonephritides
(GN) has been studied intensively. We investigated the influence of
VEGF polymorphism at position -2578 (A/C) of the VEGF promoter on
the progression of two common GN - focal segmental glomerulosclerosis
(FSGS) and IgA nephropathy (IGAN).
247 Czech patients with FSGS and IGAN entered into study. Patients
were divided into rapid progressors (RP) - 99 pts (64 males, 35 females,
mean age 45.4 ± 10.7 years) with renal failure during 5 years
since renal biopsy and slow progressors (SP) - 148 pts (91 males, 57
females, mean age 46.5±12.1 years) with stable renal function. 100
genetically unrelated healthy subjects were control group (CG). Genomic
DNA was amplified by PCR with published primers. A χ 2 -test
was used to compare the distribution of genotypes according to recessive
and dominant genetic model between RP and SP.
The distribution of the -2578 VEGF polymorphism:
AA (%) AC (%) CC (%)
FSGS
RP
SP
27.3
23.1
49.1
50
23.6
26.9
IGAN
RP
SP
22.7
22.1
40.9
52.5
36.4
25.4
CG 21 54 25
There was a tendency to negative prognostic value of the C allele on IGAN, however
a significant influence of VEGF-2578 polymorphism on the progression of FSGS and
IGAN was excluded.
Supported by IGA projects NR/9523-3, NS 9779-4
P12.165
Williams-Beuren syndrome in a Bulgarian patient diagnosed by
mLPA kit for microdeletion syndromes.
A. V. Kirov, T. Todorov, A. Todorova, S. Kalenderova, V. Mitev;
Department of Medical Chemistry and Biochemistry, Medical University, Sofia,
Bulgaria.
William-Beuren syndrome (WBS) syndrome is an autosomal dominant
disorder clinically characterized by supravalvular aortic stenosis
(SVAS), multiple peripheral pulmonary arterial stenoses, elfin face,
mental and statural deficiency, specific dental malformation, and infantile
hypercalcemia.
The genetic cause of WBS is a contiguous gene deletion of several
genes on chromosome 7q11.23. The severity of clinical symptoms and
particularly mental retardation may be related to the size of the deletion
(the number of genes involved). Recently developed for research
purposes Multiplex Ligation-dependant Probe Amplification (MLPA)
method provides a possibility to detect copy number changes (deletions
and duplications) along a single or a number of genes. We successfully
applied MLPA probe mix P245-A1 Microdeletion syndromes
to genetically diagnose a patient with clinically suspected WBS. The
obtained results showed undoubted a reduction of gene dosage for
the 3 specific WBS probes: two within Elastin(ELN) gene and one in
(LIMK1) gene, both localized in 7q11.23. The detected deletion in our
patient was associated with multiple peripheral pulmonary stenoses,
supravalvular aortic stenosis, moderate mental retardation, cognitive
problems associated with attention deficiency and hyperactivity. Facial
dismorphology was also present: thick lips, machroorchidism, micrognathia.
The MLPA analysis proved to be useful in routine genetic diagnosis of
microdeletion syndromes and particularly William-Beuren syndrome.
P12.166
is tRim50, a Williams Beuren syndrome gene, at the intersection
of autophagy and proteasome pathways?
C. Fusco 1 , M. Egorov 2 , L. Micale 1 , M. Monti 3 , M. G. Turturo 1 , B. Augello 1 , R.
Polishchuk 2 , P. Pucci 4 , F. Cozzolino 3 , G. Merla 1 ;
1 Medical Genetics Unit, IRCCS Casa Sollievo Della Sofferenza Hospital, San
Giovanni Rotondo, Italy, San Giovanni Rotondo, Italy, 2 Unit of Membrane Sorting
and Biogenesis Department of Cell Biology and Oncology, “Mario Negri Sud
Consortium”, Santa Maria Imbaro, Italy, 3 CEINGE Advanced Biotechnology
and Department of Organic Chemistry and Biochemistry, Federico II University,
Napoli, Italy, 4 3 CEINGE Advanced Biotechnology and Department of Organic
Chemistry and Biochemistry, Federico II University, Napoli, Italy.
Proteasome and Autophagy catabolic pathways have been implicated
in many human disorders. Recently, we showed that TRIM50 acts as
an E3-ubiqutin ligase. TRIM50 is hemizygous in the Williams Beuren
syndrome (WBS), a contiguous genetic disorder, caused by a 1.5 Mb
deletion at 7q11.23 that include about 25 genes. Although some of
the WBS phenotypes have been associated to some of the deleted
genes, the contributions of the remaining genes, including TRIM50, to
the multiple defects are still undetermined. To get insight on its role and
to identify putative TRIM50-interacting peptides we performed fluorescence
and electronic microscopy and mass spectrometry.
We founded that TRIM50 protein localizes in highly mobile, labile and
dynamic cytoplasmic bodies. CLEM-microscopy showed that it localizes
in the multi-vesicular structures similar to the autophagosome and
notably it colocalizes with LC3, a specific marker of autophagosomes.
Consistently, nano LC-MS/MS identified a number of putative TRIM50interacting
proteins known being implicated in the proteasome and
autophagy. Among them we showed that TRIM50 interacts with P62/
SQSTM1, an essential protein involved in the autophagic flux. p62 is
able to transfer misfolded and ubiquitinated proteins to the autophagosomes
for degradation and as TRIM50 is an E3-ubiquitin ligase, we
can speculate that TRIM50 ubiquitinates its substrates that are, then,
shuttled to the autophagosome for degradation via TRIM50-p62 complex.
These results show an unexpected role for TRIM50 on protein degradation
pathways. We anticipated that the haploinsufficiency of TRIM50
could account for a consistent part of WBS phenotype through the accumulation
and/or abnormal degradation of TRIM50 substrates.