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2009 Vienna - European Society of Human Genetics

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Molecular basis <strong>of</strong> Mendelian disorders<br />

P12.086<br />

Genetic heterogeneity <strong>of</strong> hereditary neuropathy with liability to<br />

pressure palsies at the Russian patients<br />

O. A. Schagina, T. B. Tiburkova, E. L. Dadali, G. E. Rudenskaya, A. V.<br />

Polyakov;<br />

Research centre for medical genetics RAMS, Moscow, Russian Federation.<br />

Hereditary neuropathy with liability to pressure palsies (HNPP) is an<br />

autosomal dominant painless peripheral neuropathy characterized<br />

by episodes <strong>of</strong> repeated focal pressure neuropathies at sites <strong>of</strong> entrapment/compression,<br />

with a considerable variability in the clinical<br />

course.<br />

Forty patients and twenty one healthy members from 26 unrelated<br />

families with a clinical history and examination suggestive <strong>of</strong> HNPP<br />

were observed. In 9 families HNPP were due to the common 1.5 Mb<br />

deletion. This mutation was detected on the basis <strong>of</strong> a PCR result that<br />

demonstrated loss <strong>of</strong> heterozygosity for each <strong>of</strong> four polymorphic markers<br />

in 17p11.2-12 region. Multiplex Ligation-dependent Probe Analysis<br />

(MLPA) was carried out for all patients and family members using a<br />

probes were designed to evaluate all PMP22 coding exons and five<br />

control genes: TBP, SIRT3, USP3, B2M and EEF. Disease-cause deletion<br />

was found at the three more unrelated families. At the three cases<br />

deletion de novo was the reason <strong>of</strong> disease and in the others families<br />

mutation persistence at several generations. At one patient the disease-cause<br />

duplication <strong>of</strong> 17p11.2-12 region were detect.<br />

In the absence <strong>of</strong> the deletion/duplication direct sequence analysis <strong>of</strong><br />

the all PMP22 coding exons 2-5, including their intron/exon boundaries<br />

was undertaken. One c.353C>T (Thr118Met) the previously described<br />

mutation in a heterozygotic condition and one new mutation<br />

c.75_78+2delCAGCgt were detected in two families.<br />

Thereby exciting cause was found in total at 15 from 26 unrelated families.<br />

In summary, we were able to detect genetic lesions in over 60% <strong>of</strong><br />

HNPP patients from Russia.<br />

P12.087<br />

Huntington disease pathogenesis: molecular biomarker/s in<br />

human peripheral blood and clonally striata-derived rat cells<br />

R. I. Lonigro1 , E. Bregant1 , L. Temil1 , F. Marcuzzi1 , N. Passon1 , G. Siciliano2 , E.<br />

Unti2 , G. Damante1 ;<br />

1Department <strong>of</strong> Science and Biomedical Technologies, University <strong>of</strong> Udine,<br />

Udine, Italy, 2Neuroscience Department, University <strong>of</strong> Pisa, Pisa, Italy.<br />

Huntington disease (HD) is an inherited neurodegenerative disease<br />

characterized by chorea and psychiatric disturbance. It is caused by<br />

the expansion <strong>of</strong> CAG repeats in the first exon <strong>of</strong> the gene encoding<br />

huntingtin (Htt). Normal people have a polymorphic repeat, up to 36<br />

CAG, encoding for glutamine (Gln). The mutant protein, with a longer<br />

poly-Q tract, becomes harmful to cells, particularly to cortical and<br />

striatal neurons. Mutant Htt affects many cellular processes, calcium<br />

homeostasis and mitochondrial dysfunction between others, still investigated<br />

to unveil their cause and effect relationship. An important tool<br />

for HD management could be the identification <strong>of</strong> molecular markers<br />

related to disease progression, in syntomatic and pre-symptomatic<br />

people, useful to draw early therapeutic treatments. By using quantitative<br />

RT-PCR we investigate the expression level <strong>of</strong> genes involved in<br />

calcium homeostasis in the peripheral blood <strong>of</strong> HD subjects and ageand<br />

gender- matched healthy controls. The genes selected for this<br />

study were: a purinergic receptor, P2RY5, and three calcium pumps,<br />

SERCA2, SERCA3 and PMCA1. The results we obtained demonstrate<br />

that, with respect to the controls HD patients display: 1) similar levels<br />

<strong>of</strong> SERCA3 and PMCA1 mRNAs. 2) a significant reduction <strong>of</strong> P2RY5<br />

mRNA level, in an age-related progression. 3) a significant reduction <strong>of</strong><br />

SERCA2 mRNA level at all ages. Furthermore, we propose SERCA2<br />

reduction as an early event in HD pathogenesis, since this pump is<br />

down-regulated at the protein level in clonally striata-derived rat cells<br />

expressing a doxycycline-inducible mutant Htt.<br />

P12.088<br />

Huntington disease pathogenesis: molecular biomarker/s in<br />

human peripheral blood and clonally striata-derived rat cells<br />

R. I. Lonigro 1 , E. Bregant 1 , L. Temil 1 , F. Marcuzzi 1 , N. Passon 1 , G. Siciliano 2 , E.<br />

Unti 2 , G. Damante 1 ;<br />

1 University, Udine, Italy, 2 University, Neuroscience Department, Pisa, Italy.<br />

Huntington disease (HD) is an inherited neurodegenerative disease<br />

characterized by chorea and psychiatric disturbance. It is caused by<br />

the expansion <strong>of</strong> CAG repeats in the first exon <strong>of</strong> the gene encoding<br />

huntingtin (Htt). Normal people have a polymorphic repeat, up to 36<br />

CAG, encoding for glutamine (Gln). The mutant protein, with a longer<br />

poly-Q tract, becomes harmful to cells, particularly to cortical and<br />

striatal neurons. Mutant Htt affects many cellular processes, calcium<br />

homeostasis and mitochondrial dysfunction between others, still investigated<br />

to unveil their cause and effect relationship. An important tool<br />

for HD management could be the identification <strong>of</strong> molecular markers<br />

related to disease progression, in syntomatic and pre-symptomatic<br />

people, useful to draw early therapeutic treatments. By using quantitative<br />

RT-PCR we investigate the expression level <strong>of</strong> genes involved in<br />

calcium homeostasis in the peripheral blood <strong>of</strong> HD subjects and age-<br />

and gender- matched healthy controls. The genes selected for this<br />

study were: a purinergic receptor, P2RY5, and three calcium pumps,<br />

SERCA2, SERCA3 and PMCA1. The results we obtained demonstrate<br />

that, with respect to the controls HD patients display: 1) similar levels<br />

<strong>of</strong> SERCA3 and PMCA1 mRNAs. 2) a significant reduction <strong>of</strong> P2RY5<br />

mRNA level, in an age-related progression. 3) a significant reduction <strong>of</strong><br />

SERCA2 mRNA level at all ages. Furthermore, we propose SERCA2<br />

reduction as an early event in HD pathogenesis, since this pump is<br />

down-regulated at the protein level in clonally striata-derived rat cells<br />

expressing a doxycycline-inducible mutant Htt.<br />

P12.089<br />

Exclusion <strong>of</strong> trinucleotide repeat expansions in JPH3 gene<br />

causing disease in italian patients with Huntington-like<br />

phenotype<br />

A. Patitucci, A. Magariello, T. Sprovieri, L. Citrigno, C. Ungaro, A. L. Gabriele,<br />

F. L. Conforti, R. Mazzei, M. Muglia;<br />

Institute <strong>of</strong> Neurological Sciences, CNR, Mangone (CS), Italy.<br />

Huntington disease-like 2 (HDL2) is a rare autosomal dominant disorder<br />

<strong>of</strong> the nervous system, apparently indistinguishable from Huntington<br />

disease (HD). HDL2 belongs to a group <strong>of</strong> HDL disorders, also<br />

including Huntington disease-like 1 (HDL1), an autosomal dominant<br />

disease caused by an extra octapeptide repeat in the prion protein<br />

gene (PRNP), on chromosome 20p12; and Huntington disease-like<br />

3 (HDL3), an autosomal recessive disease, mapped to 4p15.3. Furthermore,<br />

dentatorubral-pallidoluysian atrophy (DRPLA) and spinocerebellar<br />

ataxia type 17 (SCA17), may also have overlapping symptoms<br />

with HD.<br />

HDL2 is caused by the expansion above 40 CAG repeats, in a variably<br />

spliced exon <strong>of</strong> the junctophilin-3 gene (JPH3), on chromosome<br />

16q24.3. The pathogenic mechanism underlying HDL2 remains unknown.<br />

Different JPH3 transcripts caused by alternative splicing and<br />

different polyadenylation sites have been described.<br />

To date, the expansion in JPH3 gene has been found only in patients<br />

with African ancestry. A very recent paper reports the first HDL2 case<br />

with an apparent <strong>European</strong> ancestry. In order to find a new founder<br />

effect on Caucasian population, we performed a mutational analysis in<br />

JPH3 gene in 132 Italian patients negative for HD disease. All patients<br />

tested were negative for the expansion on JPH3 according to the available<br />

data on Polish, Yugoslavian and Portuguese populations.<br />

Further investigations for HDL1 and HDL3 forms, as well as DRPLA<br />

and SCA17, will be performed on our patients. However, the diagnosis<br />

<strong>of</strong> HDL2 should always be considered, regardless <strong>of</strong> the apparent origin<br />

<strong>of</strong> the family, particularly in populations <strong>of</strong> mixed ancestry.<br />

P12.090<br />

PcR <strong>of</strong> (cAG)n repeats in Bulgarian Huntington Horea patients<br />

A. Todorova 1 , T. Todorov 1 , B. Georgieva 1 , A. Kirov 1 , L. Angelova 2 , S. Kalenderova<br />

1 , V. Mitev 1 ;<br />

1 Department <strong>of</strong> Medical Chemistry and Biochemistry, Medical University, S<strong>of</strong>ia,<br />

Bulgaria, 2 Laboratory <strong>of</strong> Medical <strong>Genetics</strong>, Medical University, Varna, Bulgaria.<br />

Huntington disease (HD) is an autosomal dominant neurodegenerative<br />

disorder that gives rise to progressive, selective (localized) neural<br />

cell death associated with choreic movements, rigidity and dementia<br />

frequently associated with seizures. The disease is associated with<br />

increases in the length <strong>of</strong> a CAG triplet repeat in IT15 gene called<br />

‘huntingtin’ located on chromosome 4p16.3.<br />

The normal size <strong>of</strong> the CAG triplet <strong>of</strong> the HD is ≤35 repeats, the pathological<br />

number <strong>of</strong> the CAG triplet is larger than 36 repeats with different<br />

penetrance (36-39 repeats -

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