24.08.2013 Views

2009 Vienna - European Society of Human Genetics

2009 Vienna - European Society of Human Genetics

2009 Vienna - European Society of Human Genetics

SHOW MORE
SHOW LESS

You also want an ePaper? Increase the reach of your titles

YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.

Cytogenetics<br />

P03.151<br />

Familial Fraxe syndrome detected using mLPA technique<br />

A. Zuñiga, I. Pitarch, Y. Bello, A. Guerrero;<br />

Hospital de la Ribera, Alzira (valencia), Spain.<br />

We have employed MLPA technique in order to study a family with non<br />

specific mental impairment. The term non-specific or non-syndromic<br />

X-linked mental retardation (MRX) was introduced to indicate a condition<br />

segregating in an X-linked manner in which male patients have no<br />

consistent phenotypic manifestations other than MR. Nineteen genes<br />

responsible for MRX have been identified so far. P106 MRX MLPA<br />

probemix (MRC Holland MLPA®) can be used to detect copy number<br />

changes <strong>of</strong> several genes on the X-chromosome that have been implicated<br />

in (non-specific) X-linked mental retardation.<br />

Mother, a daughter (11 year old) and a son (3 year old) were analyzed<br />

using P106 MRX MLPA and a deletion was detected in AFF2<br />

(FMR2) probe. Further analysis using conventional PCR techniques<br />

and sequencing confirmed that members <strong>of</strong> family were carriers <strong>of</strong> an<br />

expanded CGG region in FMR2 gene. Mother was carrier <strong>of</strong> an expanded<br />

allele with 70 CGG repeats, allele <strong>of</strong> daughter was expanded<br />

till 120 CGGs and allele <strong>of</strong> son was 135 CGGs. Son has a more severe<br />

phenotype, but both mother and daughter had a mild mental retardation.<br />

FRAXE fragile site associated mental retardation remains<br />

unique among X-linked mental retardation phenotypes due to its very<br />

mild to borderline nature (50 < IQ< 85). It is the most prevalent form<br />

<strong>of</strong> non-specific X-linked mental retardation so far delineated, with an<br />

estimated incidence <strong>of</strong> at least 1/50-100,000 males. The FRAXE site<br />

is within, or immediately adjacent to, the 5’ untranslated region <strong>of</strong> the<br />

FMR2 gene.<br />

P03.152<br />

Prevalence <strong>of</strong> Fragile X syndrome in mentally retarded patients<br />

from Latvia<br />

Z. Daneberga 1,2 , Z. Krumina 1 , B. Lace 1,2 , D. Bauze 1 , N. Pronina 1 , R. Lugovska 1 ;<br />

1 Medical Genetic Clinic, Riga, Latvia, 2 Riga Stradins University, Riga, Latvia.<br />

The most common form <strong>of</strong> X-linked mental retardation (XLMR) is the<br />

Fragile X mental-retardation syndrome (FXS). Mutations at FRAXA<br />

locus on distal Xq may cause mental impairment. Most common mutation<br />

at FRAXA locus is expansion <strong>of</strong> CGG triplet repeats located in<br />

the 5’-untranslated region <strong>of</strong> the fragile X mental retardation-1 (FMR1)<br />

gene.<br />

The aim <strong>of</strong> this study was to estimate the prevalence <strong>of</strong> FXS in Latvia<br />

and characterize the FMR1 CGG-repeat structure in Latvian patients<br />

exhibiting mental retardation. The group <strong>of</strong> 374 unrelated patients<br />

with mental retardation (MR) referred from clinical geneticists was<br />

screened by PCR for a normal allele. The final diagnosis <strong>of</strong> FXS has<br />

been confirmed by Southern blotting. DXS548-FRAXAC1-FRAXAC2-<br />

ATL1 haplotype for FXS patients were estimated. DNA sequencing for<br />

the estimation <strong>of</strong> AGG inserts structure for gray zone (35-50 repeats)<br />

alleles was used.<br />

10 affected patients were detected (detection rate 2.67%). Calculated<br />

prevalence <strong>of</strong> FMR1 full mutation is 1:6173 for male in general Latvian<br />

population. After active cascade testing in 6 FXS families 6 female<br />

permutation carriers, 3 females with full mutation and 4 affected males<br />

were found. The highest incidence among FXS patients for haplotype<br />

4-3-4-G was found. The prevalence <strong>of</strong> 29, 30 and 31 CGG repeats for<br />

normal alleles were detected.<br />

P03.153<br />

FmR1 gene stability: distribution <strong>of</strong> premutation and<br />

intermediate alleles in five basque valleys<br />

I. Arrieta Saez 1 , M. Telez 1 , I. Huerta 1 , P. Flores 2 , B. Criado 3 , J. Ramirez 1 , M.<br />

Barasoain 1 , M. Hernández 1 , A. González 4 ;<br />

1 Department <strong>of</strong> <strong>Genetics</strong>, Faculty <strong>of</strong> Science and Technology, University <strong>of</strong><br />

the Basque Country, Bilbao, Spain, 2 Department <strong>of</strong> Nursing, School <strong>of</strong> Nursing,<br />

University <strong>of</strong> the Basque Country, Bilbao, Spain, 3 High School Da Maia,<br />

CESPU, Porto, Portugal, 4 Department <strong>of</strong> Internal Medicine, Faculty <strong>of</strong> Medicine,<br />

University <strong>of</strong> the Basque Country, Bilbao, Spain.<br />

Fragile X Syndrome (FXS) is the most common form <strong>of</strong> inherited mental<br />

retardation. The molecular basis is usually the unstable expansion<br />

<strong>of</strong> a CGG repeat in the FMR1 gene.The CGG sequence is polymorphic<br />

with respect to size and purity <strong>of</strong> the repeat. We had previously<br />

analyzed a sample <strong>of</strong> two Basque valleys (Markina and Arratia). In<br />

the present work we extend the study to another five isolated valleys<br />

(Uribe, Gernika, Durango, Goierri and Larraun). The results showed<br />

that differences in factors implicated in CGG repeat instability (CGG<br />

repeat size, DXS548/FRAXAC1 haplotypes and AGG interspersion<br />

pattern) are present in the Basque populations analyzed.<br />

P03.154<br />

Prevalence <strong>of</strong> the expanded alleles <strong>of</strong> the FmR1 gene in blood<br />

spots from newborn males in a spanish population<br />

I. Fernández-Carvajal 1 , P. Walichiewicz 2 , X. Xiaosen 2 , R. Pan 2 , P. J. Hagerman<br />

3,4 , M. J. Alonso 1 , J. J. Telleria 1 , A. Blanco 1 , F. Tassone 2,5 ;<br />

1 1I.B.G.M.Unidad de Diagnóstico Genético y Perinatal. Universidad de Valladolid,<br />

Valladolid, Spain, 2 Department <strong>of</strong> Biochemistry and Molecular Medicine,<br />

University <strong>of</strong> California, School <strong>of</strong> Medicine, 3 Department <strong>of</strong> Biochemistry and<br />

Molecular Medicine, University <strong>of</strong> California, School <strong>of</strong> Medicine, Davis, CA,<br />

United States, 4 M.I.N.D. Institute, University <strong>of</strong> California Davis HealthSystem,,<br />

Sacramento, CA, United States, 5 M.I.N.D. Institute, University <strong>of</strong> California<br />

Davis HealthSystem, Sacramento, CA, United States.<br />

Fragile X syndrome is the most common inherited form <strong>of</strong> intellectual<br />

disability. The frequencies <strong>of</strong> full mutation (>200 CGG repeats) have<br />

varied widely from 1/ 2,000 to 1/ 8,000 depending on the nature <strong>of</strong><br />

ascertainment. There remains uncertainty regarding the premutation<br />

allele frequencies due in part to lingering issues <strong>of</strong> ascertainment bias,<br />

but also to real frequency differences across ethnic and regional populations.<br />

Setting and Methods: We report results <strong>of</strong> a newborn screening study<br />

<strong>of</strong> 5,267 male blood spots collected from Castilla y Leon, the Northwest<br />

region <strong>of</strong> Spain. The blood spots were screened by a rapid PCR-based<br />

method that is capable <strong>of</strong> identifying the presence <strong>of</strong> all expanded alleles<br />

categorized as intermediate alleles (45-54 CGG repeats), premutation<br />

(55-200 CGG repeats), and full mutation (>200 CGG repeats).<br />

Results: The most common alleles, 29 and 30 CGG repeats, within<br />

this population accounted for approximately 38% <strong>of</strong> all. We found 199<br />

gray-zone alleles (1 in 26; 95%CI, 1/23 - 1/30), 21 premutation alleles<br />

(1 in 251; 95%CI, 1/164 - 1/385), and 2 full mutation alleles (1 in 2,633;<br />

95%CI, 1/714 - 1/10,000).<br />

Conclusions: The frequency <strong>of</strong> premutation alleles is three times higher<br />

than the <strong>of</strong>t-quoted value <strong>of</strong> 1 in 813 from an Eastern Canadian<br />

population, and is fully consistent with the results <strong>of</strong> large-scale Israeli<br />

screening studies. Our results demonstrate that newborn screening<br />

for the presence <strong>of</strong> expanded FMR1 alleles is an effective means for<br />

defining the distribution <strong>of</strong> expanded FMR1 alleles in newborn populations<br />

and is suitable for large-scale newborn screening.<br />

P03.155<br />

molecular Genetic test for X-Fragile syndrome in 2008 iVi<br />

Assisted Reproduction treatments.<br />

A. Garda-Salas, I. Pérez, P. Albero, C. Méndez, M. Martínez, M. Nicolás, L.<br />

Fernández, J. Landeras;<br />

IVI-Murcia, Murcia, Spain.<br />

Since 2007, our company, “Instituto Valenciano de Infertilidad” (IVI)<br />

has implemented the routine molecular diagnosis <strong>of</strong> X-FRAGILE Syndrome<br />

(FRAXA) into the oocyte donation program. FRAXA is one <strong>of</strong><br />

the greatest genetic prevalence illnesses in general population. The<br />

prevalence <strong>of</strong> full-mutation males in white population is aprox. 1/4,000.<br />

FRAXA is the most common cause associated to mental family inherited<br />

and represents among 15-20% <strong>of</strong> the total mental delay related<br />

to X cr. This illness has its origin in the deficiency <strong>of</strong> FMR1 protein<br />

synthesis. The expansion <strong>of</strong> the “dynamic” and repetitive region CGG,<br />

5´ to Fmr-1, causes it´s methylation and repression <strong>of</strong> expression. According<br />

repetitions number <strong>of</strong> the CGG tri-nucleotide, this region is<br />

considered normal (200 CGGn).<br />

We present our most recent data for these analysis, using the Abbott<br />

Molecular protocol, called Fragile X-PCR Test. During 2008 we studied<br />

3,485 women from different cities in Spain. All these women were<br />

susceptible oocyte’donors for processing <strong>of</strong> assisted reproductive<br />

treatments (ART). In conclusion, we found 17 (0,49 %) premutation<br />

carriers; 52 (1,49%) “intermediate” carriers and 1 (0,028%) possible<br />

full mutation carrier; 1/50 women were excluded from the donation<br />

program.<br />

The knowledge <strong>of</strong> the fragile X premutation carrier condition or full<br />

mutation carrier will permit the donor to receive the appropriate genetic<br />

counsel for reproductive end. Finally, the exclusion from the oocyte

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!