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.

Genomics, Genomic technology and Epigenetics<br />

Pediatrics Endocrinology and Diabetes, Berlin, Germany, 4 Technische Universität<br />

München, Institute <strong>of</strong> <strong>Human</strong> <strong>Genetics</strong>, Munich, Germany.<br />

Capillary sequencing <strong>of</strong> the coding region <strong>of</strong> the ABCC8 and KCNJ11<br />

genes in patients with diffuse Congenital Hyperinsulinism <strong>of</strong> Infancy<br />

(CHI) results in a low mutation detection rate. In 23 out <strong>of</strong> 44 patients<br />

no mutations were found and 9 patients had a heterozygous mutation.<br />

In order to detect further rare variants, we resequenced the entire genomic<br />

region <strong>of</strong> the ABCC8 and KCNJ11 genes (100 kb) on a GA II<br />

system in 24 samples and evaluated the sensitivity and specificity <strong>of</strong><br />

variant detection. The region was amplified with 19 long-range PCR<br />

reactions. For library construction, a beta-version <strong>of</strong> the Illumina multiplexing<br />

oligonucleotide paired-end kit was used and up to 12 samples<br />

were processed in a single lane. Data were analyzed using the MAQ<br />

s<strong>of</strong>tware. Coverage was between 300- and 5000-fold. Preliminary<br />

analysis revealed several false positive variants that were only found<br />

on either the forward or reverse strand and showed preference for<br />

specific neighboring nucleotides. After filtering for this systematic error,<br />

we detected 399 out <strong>of</strong> 402 previously sequenced coding SNPs/mutations.<br />

One <strong>of</strong> the three differing positions could be accounted for by low<br />

coverage in this region. The other two were unambiguous calls. Additionally<br />

to the known variants, we detected 88 new SNPs and 8 new<br />

indels in the intron- and intergenic regions. 59.1% SNPs and 62.5%<br />

indels were confined to a single patient. The other variants are encountered<br />

in at least two individuals. Population frequencies <strong>of</strong> these<br />

variants are being investigated.<br />

P11.025<br />

Finding copy Number Polymorphism in the swiss Population<br />

A. Valsesia 1,2 , T. Johnson 2,3 , Z. Kutalik 2,3 , CoLaus Consortium, B. J. Stevenson<br />

1,2 , C. V. Jongeneel 1,2 , J. S. Beckmann 4,3 , S. Bergmann 2,3 ;<br />

1 Ludwig Institute for Cancer Research, Lausanne, Switzerland, 2 Swiss Institute<br />

<strong>of</strong> Bioinformatics, Lausanne, Switzerland, 3 Department <strong>of</strong> Medical <strong>Genetics</strong><br />

UNIL, Lausanne, Switzerland, 4 Service <strong>of</strong> Medical <strong>Genetics</strong>, CHUV, Lausanne,<br />

Switzerland.<br />

Having technologies like microarrays and ultra-high throughput sequencing,<br />

facilitate the identification <strong>of</strong> genetic structural variations.<br />

SNPs are used to investigate susceptibility to common diseases, yet<br />

they explain but a small fraction <strong>of</strong> the phenotypic variance. Copy<br />

number variation (CNV) is the most frequent structural variation in the<br />

human genome and encompasses more nucleotides than SNPs. It is<br />

likely that CNVs explain at least some <strong>of</strong> phenotypic variance that cannot<br />

be attributed to SNPs, but the extent <strong>of</strong> this contribution remains<br />

unknown.<br />

We present an approach to detect CNVs from Affymetrix arrays and to<br />

combine these into Copy Number Polymorphic regions (CNPs). Using<br />

an HMM we attribute a copy number state to each SNP probed for a<br />

collection <strong>of</strong> individuals. We then perform a principal component analysis<br />

on a window <strong>of</strong> SNP data across individuals. Only components that<br />

explain most <strong>of</strong> the variance are used to cluster SNPs into CNPs.<br />

Based on this merging method, we report a comprehensive variation<br />

map on the CoLaus dataset (Cohort Lausannoise - a 6000 individual<br />

population). This map describes 1853 common events (>=1% frequency)<br />

and 5797 rare events (frequency between 0.1% and 1%) having<br />

respectively a median (mean) size <strong>of</strong> 140 (201) Kb and 81 (127) Kb.<br />

17.1% <strong>of</strong> the rare CNVs and 17.97% <strong>of</strong> the common CNPs were already<br />

known. The remaining predicted variants are good candidates<br />

for being structural variations in <strong>European</strong> populations that should be<br />

replicated by independent studies. Our CNV map will facilitate association<br />

studies <strong>of</strong> clinical phenotypes with these variants.<br />

P11.026<br />

Detection <strong>of</strong> copy number variations (cNV) in patients with<br />

mental retardation using high density sNP microarrays<br />

N. Rivera Brugués 1 , M. Hempel 2 , S. Spranger 3 , B. Kazmierczak 3 , T. Meitinger<br />

1,2 , T. M. Strom 1,2 ;<br />

1 Institute <strong>of</strong> <strong>Human</strong> <strong>Genetics</strong>, Helmholtz Zentrum München, German Research<br />

Center for Environmental Health, Neuherberg, Germany, 2 Institute <strong>of</strong> <strong>Human</strong><br />

<strong>Genetics</strong>, Technische Univeristät München, Munich, Germany, 3 Praxis für<br />

<strong>Human</strong>genetik, Bremen, Germany.<br />

Chromosomal abnormalities are a major cause <strong>of</strong> mental retardation.<br />

Whole-genome array-based technologies have increased the detection<br />

rate <strong>of</strong> cryptic aneusomies among these patients up to 10-20%.<br />

DNAs from 109 children with MR and normal G-banded chromosomes<br />

and 1 mentally retarded child with a de novo balanced reciprocal translocation<br />

were evaluated for rearrangements by Illumina <strong>Human</strong>610-<br />

Quadv1_B arrays. Data quality was assessed with standard deviation<br />

(mean SD: 0.19) and mean absolute deviation (mean MAD: 0.12)<br />

<strong>of</strong> the log2 intensity ratios. In male samples, a signal-to-noise ratio<br />

(mean SNR: 3.82) was calculated. CNVs were called using circular<br />

binary segmentation (DNAcopy). Candidate CNVs were compared<br />

with known polymorphisms and relevant regions were confirmed by<br />

qPCR.<br />

A total <strong>of</strong> 3,087 CNVs (2,436 losses, 651 gains) ranging in length from<br />

118 to 13,386,172 base pairs (mean 85,224, median 24,331) were<br />

detected. 152 out <strong>of</strong> 3,087 candidate regions were investigated. Of<br />

these, 58 (38.2%) were confirmed, 94 (61.8%) were false-positive. 75<br />

(79.8%) <strong>of</strong> the false positive were detected in regions defined by 20<br />

SNP.<br />

This study led to the identification <strong>of</strong> 13 de novo CNVs and one maternally<br />

inherited Xq13.1 deletion in a male patient. The inheritance <strong>of</strong> 5<br />

CNVs could not be established because <strong>of</strong> missing parental DNA.<br />

ID Chromosome Gain/Loss<br />

Position<br />

UCSC hg18<br />

Number Number Length Known<br />

<strong>of</strong> SNPs <strong>of</strong> Genes (Mb) Syndrome<br />

28181 4q28.3-q31.1 Loss 136,619,480- 140,515,101 770 7 3.895 no<br />

28181 6q16.2-q21 Loss 98,465,339- 111,851,511 2628 >50 13.386 no<br />

28181 6q24.1 Loss 141,216,188- 142,860,121 212 3 1.643 no<br />

35858 2p12-p13.3 Loss 72,397,638- 77,632,757 1074 >50 5.235 no<br />

35929 13q32.3 Loss 98,706,939- 98,709,985 6 1 0.003 no<br />

37497 14q11.2 Loss 20,388,473- 21,164,794 222 21 0.776 no<br />

38749 16p11.2 Loss 28,363,967- 28,549,743 34 8 0.185 16p11.2-p12.2 deletion<br />

38749 16p11.2 Loss 28,733,550- 29,283,628 89 9 0.550 16p11.2-p12.2 deletion<br />

39753 6p25.1 Loss 5,104,063- 5,406,969 92 2 0.302 no<br />

39753 23p21.3 Gain 29,043,064- 29,392,222 60 1 0.349 no<br />

40633 13q12.11 Gain 19,165,733- 19,942,459 200 7 0.776 no<br />

43308 17q11.2 Loss 26,024,127- 27,392,540 211 14 1.368 NF1 type I<br />

44289 2q23.3-q24.2 Loss 153,522,479- 161,822,306 1617 25 8.229 no<br />

44399 23q13.1 Loss 69,341,389- 69,381,997 6 2 0.040 no<br />

33361 4p16.3 Loss* 7,764- 1,504,781 289 24 1.497 no<br />

33361 4p16.3-p15.33 Gain* 1,504,782- 13,259,183 2991 >50 13.251 no<br />

32808 6q14.1 Loss* 79,576,561- 80,104,580 75 3 0.528 no<br />

30921 2p25.3 Gain* 1,069,320- 1,752,354 195 3 0.683 no<br />

31166 23p22.2 Gain* 15,952,583- 16,694,026 90 4 0.741 no<br />

P11.027<br />

A genome-wide cpG island methylation analysis microarray<br />

A. Wong1 , R. Straussman2 , Z. Yakhini1 , I. Steinfeld1 , H. Cedar2 , A. Ashutosh1 , R.<br />

M. Saxena1 , D. Roberts1 ;<br />

1 2 Agilent Technologies, Santa Clara, CA, United States, Hebrew University,<br />

Jerusalem, Israel.<br />

CpG islands are stretches <strong>of</strong> high GC content DNA containing multiple<br />

CpG dinucleotides. When CpG dinucleotides within these islands<br />

are methylated, especially in promoter regions, expression <strong>of</strong> the corresponding<br />

downstream genes is <strong>of</strong>ten repressed. Aberrant CpG island<br />

methylation is implicated in cancer. We have refined a protocol<br />

for methylated DNA immunoprecipitation (mDIP) and coupled it with<br />

microarray detection. DNA isolated by mDIP is fluorescently labeled<br />

and hybridized to an oligonucleotide microarray that specifically represents<br />

the unique CpG islands in the human genome. This microarray<br />

contains ~237,000 oligo probes tiling ~20,000 CpG islands, with an average<br />

spacing between probes <strong>of</strong> 95 base pairs. In addition, we have<br />

tiled CG rich promoter regions. As pro<strong>of</strong> <strong>of</strong> concept we perform mDIP<br />

and microarray analysis <strong>of</strong> human genomic DNA samples from normal<br />

tissues. We compare our mDIP array data with bisulfite sequencing<br />

data. We demonstrate the ability <strong>of</strong> our array based methylation assay<br />

to distinguish probes corresponding to methylated regions from probes<br />

corresponding to unmethylated regions. We then apply the whole-genome<br />

assay to tumor and normal DNA.and identify differential methylation<br />

patterns.

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

Saved successfully!

Ooh no, something went wrong!