2009 Vienna - European Society of Human Genetics
2009 Vienna - European Society of Human Genetics
2009 Vienna - European Society of Human Genetics
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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