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2009 Vienna - European Society of Human Genetics

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

patients, but no controls, and is under further investigation.<br />

Four patients carried de-novo WT1 mutations, 3 had previously characterized<br />

mutations (1 with IVS9+5G>A, and 2 with R394W,) and the<br />

fourth had a novel mutation R366H, predicted to be pathogenic in<br />

silico. Karyotype analysis showed XX in 3 patients, consistent with the<br />

female phenotype, but one (with R394W), was XY and had complete<br />

gonadal dysgenesis.<br />

Thus 7/19 sporadic SRNS patients, (but no familial cases) had NPHS2<br />

or WT1 mutations, indicating that molecular investigation <strong>of</strong> these<br />

genes is useful to support definitive diagnosis and management <strong>of</strong><br />

pediatric SRNS..<br />

P12.120<br />

Genotype-phenotype correlations in patients with hereditary<br />

neurodegenerative diseases<br />

N. V. Hryshchenko1 , E. I. Patscun2 , L. A. Livshits1 ;<br />

1 2 Institute <strong>of</strong> Molecular Biology and <strong>Genetics</strong>, Kiev, Ukraine, Regional Clinical<br />

Hospital, Uzhgorod, Ukraine.<br />

Neurodegenerative diseases (ND) are characterized by progressive<br />

nervous system (NS) dysfunction, associated with mutation in genes<br />

leads to atrophy <strong>of</strong> the affected central or peripheral NS structures.<br />

To summarize our experience in the field <strong>of</strong> neurogenetics we provide<br />

the investigation <strong>of</strong> mutations associated with various NS dysfunction<br />

in patients with Huntington’s disease (HD) and Charcot-Marie-Tooth<br />

(CMT) disease.<br />

HD is a common disorder <strong>of</strong> central NS caused by expansion <strong>of</strong> CAGrepeats<br />

in the IT15. CMT is a heterogeneous group <strong>of</strong> peripheral NS<br />

diseases with more than 20 involved loci. The most common types <strong>of</strong><br />

CMT are due to mutations in PMP22 and Cx32.<br />

Analysis <strong>of</strong> CAG-, CCG- and del2642 <strong>of</strong> IT15 gene polymorphisms<br />

has been performed in patients with HD. We have provided the<br />

screening <strong>of</strong> PMP22 duplications/deletion and Cx32 point mutations<br />

in CMT patients. 35 HD-probands had expanded allele <strong>of</strong> IT15 (39-<br />

52 CAG-repeats). The significant differences in sex-determined instability<br />

<strong>of</strong> CAG-repeats inheritance have been revealed. The association<br />

between del2642 and the age <strong>of</strong> HD onset has been analyzed.<br />

PMP22-duplications were found in 21 CMT-families. We also detected<br />

the heterozygote PMP22 gene deletion in two patients with specific<br />

HNPP-phenotype. Mutation screening <strong>of</strong> Cx32 revealed 2 brothers<br />

with Arg22Gln mutation.Our data showed the association between different<br />

types <strong>of</strong> IT15, PMP22 and Cx32 genes mutations and specific<br />

abnormalities <strong>of</strong> the NS. Obtained data would be useful for better understanding<br />

<strong>of</strong> ND pathogenesis and for providing new individualized<br />

therapy for curing <strong>of</strong> neurological disorders.<br />

P12.121<br />

Identification and characterization <strong>of</strong> mutations causing<br />

Niemann-Pick disease types A/B in spanish patients<br />

L. Rodríguez-Pascau 1 , L. Gort 2 , E. H. Schuchman 3 , A. Chabás 2 , L. Vilageliu 1 ,<br />

D. Grinberg 1 ;<br />

1 Departament de Genètica, Facultat de Biologia, Universitat de Barcelona,<br />

CIBERER, IBUB, Barcelona, Spain, 2 Institut de Bioquímica Clínica, Hospital<br />

Clínic, Corporació Sanitària Clínic, CIBERER, Barcelona, Spain, 3 Department<br />

<strong>of</strong> <strong>Genetics</strong> & Genomic Sciences, Mount Sinai School <strong>of</strong> Medicine, New York,<br />

NY, United States.<br />

Niemann-Pick disease type A/B (NPD A/B) is an autosomal recessive<br />

lysosomal storage disorder caused by acid sphingomyelinase (ASM)<br />

deficiency due to mutations in the SMPD1 gene. Type A NPD is the<br />

severe neurological form whereas type B NPD patients have no neurological<br />

manifestations. In this work, we present a molecular analysis <strong>of</strong><br />

19 Spanish patients and 2 from Maghreb, 8 with type A and 13 with type<br />

B NPD. All mutant SMPD1 alleles were identified, including 17 different<br />

mutations, 10 <strong>of</strong> which were novel: c.503G>A (p.W168X), c.939C>A<br />

(p.Y313X), c. 1100A>G (p.Y367C), c.1400A>C (p.Y467S), c.1445C>A<br />

(p.A482E), c.1456A>G (p.T486A), c.1159delC (p.R387VfsX7),<br />

c.1169_1171delTCT (p.F390del), c.1257+4_1257+7delAGGG, and<br />

c.1774_1776delACT (p.T592del). The only frequent mutations in the<br />

21 NPD patients were c.1823_1825delGCC (p.R608del) (38%) and<br />

c.1445C>A (p.A482E) (9%). For most <strong>of</strong> the mutations a good correlation<br />

between genotype and phenotype could be established and,<br />

in particular, the p.R608del-type B association was confirmed. Six <strong>of</strong><br />

the mutations found in Spanish patients, and two other mutations for<br />

comparison, were expressed in vitro to establish their residual enzy-<br />

matic activities. All mutant alleles were confirmed to be disease-causing<br />

due to their low enzyme activity, although western blot analyses<br />

showed that a normal amount <strong>of</strong> protein was synthesized. The mutation<br />

c.1257+4_1257+7delAGGG, which affects a non-canonical donor<br />

splice site, was analysed at the RNA level. Only aberrant mRNAs, corresponding<br />

to previously reported minor SMPD1 transcripts, which do<br />

not code for functional enzymes, were produced by this allele. This<br />

study is the first exhaustive mutational analysis <strong>of</strong> Spanish Niemann-<br />

Pick A/B disease patients.<br />

P12.122<br />

the Evaluation <strong>of</strong> clinical selection criteria in NsHL molecular<br />

Results<br />

C. Radaelli 1 , P. Castorina 2,3 , F. Lalatta 2 , U. Ambrosetti 3 , A. Cesarani 3 , A. Murri 4 ,<br />

D. Cuda 4 , F. Sironi 1 , L. Trotta 1 , D. A. Coviello 1 , P. Primignani 1 ;<br />

1 Medical <strong>Genetics</strong> Laboratory - Fondazione IRCCS, Ospedale Maggiore Policlinico,<br />

Mangiagalli e Regina Elena, Milan, Italy, 2 Medical Genetic Service<br />

- Fondazione IRCCS, Ospedale Maggiore Policlinico, Mangiagalli e Regina<br />

Elena, Milan, Italy, 3 ENT Audiology Department - Fondazione IRCCS Ospedale<br />

Maggiore Policlinico, Mangiagalli e Regina Elena., Milan, Italy, 4 ENT Audiology<br />

Department - Ospedale “Guglielmo da Saliceto”, Piacenza, Italy.<br />

Since January 2001 we have studied more than 1000 subjects among<br />

deaf patients, family members and deaf/carrier partners.<br />

The majority <strong>of</strong> our patient’s population has been recruited through<br />

the Genetic Service <strong>of</strong> the O.R.L. Department <strong>of</strong> our Hospital in Milan<br />

since 2001 and through the O.R.L. Service in Piacenza starting from<br />

2004. The 658 subjects afferent to our Hospital were affected by neurosensorial<br />

deafness with various degrees (from mild to pr<strong>of</strong>ound) <strong>of</strong><br />

hearing loss (HL), while the 131 patients from Piacenza Hospital had a<br />

HL degree ranging from severe to pr<strong>of</strong>ound.<br />

All patients were analysed for mutations <strong>of</strong> the entire Cx26 gene<br />

(GJB2), and for the Δ(GJB6-D13S1830) deletion. The analysis <strong>of</strong> the<br />

deafness-causing A1555G substitution in mitochondrial (mt)DNA was<br />

carried out in our cohort <strong>of</strong> patients while, usually, in the second group<br />

this analysis is not requested. In order to compare the two different<br />

criteria <strong>of</strong> clinical selection and the concerning molecular results, we<br />

performed the mtDNA analysis in all the subjects with only one or without<br />

Cx26 mutations. In the first group we found a lower percentage <strong>of</strong><br />

positive Cx26/Cx30 cases in comparison to the second group (25.8%<br />

vs. 53.4%), but a higher percentage <strong>of</strong> dominant mutations (4.7% vs.<br />

1.5%); the mtA1555G was found only in the first group <strong>of</strong> the affected<br />

patients (3%). We conclude that clinical selection based on the severity<br />

<strong>of</strong> HL is quite relevant to obtain high percentage <strong>of</strong> Cx26 positive,<br />

but may allow the missing <strong>of</strong> uncommon GJB2 genotypes and mt mutations.<br />

P12.123<br />

Frequency <strong>of</strong> 35delG mutations in cochlear implant recipients .<br />

M. Falah1 , M. Houshmand2 , S. Akbaroghli3 , S. Seyedhassani2 , M. Farhadi1 ;<br />

1Department and research center <strong>of</strong> ENT and Head & neck surgery Iran University<br />

<strong>of</strong> Medical Sciences., Tehran, Islamic Republic <strong>of</strong> Iran, 2National Institute<br />

for Genetic Engineering and Biotechnology., Tehran, Islamic Republic <strong>of</strong> Iran,<br />

3Deputy for cultural affairs and prevention <strong>of</strong> Iran Welfare Organization, Tehran,<br />

Islamic Republic <strong>of</strong> Iran.<br />

Objective: Hearing impairment is the most common sensory disorder,<br />

present in 1 <strong>of</strong> every 500 newborns. Nonsyndromic sensorineural hearing<br />

loss(NSHL) is inherited in a predominantly autosomal recessive<br />

manner in up to 70% <strong>of</strong> cases. It is also an extremely heterogeneous<br />

trait. The gene more <strong>of</strong>ten involved is GJB2, encoding the protein Connexin<br />

26. In most populations a single mutation, 35delG, accounts for<br />

most cases <strong>of</strong> NSHI .<br />

Methods: 90 patients receiving cochlear implants were ascertained<br />

through research centre <strong>of</strong> ENT & head and neck surgery .After genetic<br />

counseling for them DNA isolated from the peripheral blood, all<br />

patients were molecularly evaluated for the presence <strong>of</strong> the 35delG<br />

mutation by ARMS /PCR.<br />

Result: We investigated 90 patients , 44.9% male and 55.1% female ,<br />

that 90% <strong>of</strong> them were < 10 years old that receiving cochlear implant<br />

.<br />

70.8% <strong>of</strong> these patients were born on consanguine family and 12.4%<br />

<strong>of</strong> them were syndromic hearing loss.<br />

Among these patients 86.5% were normal, 10.1 % homozygote and<br />

3.4% heterozygote for 35delG mutation.

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