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2009 Vienna - European Society of Human Genetics

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Cytogenetics<br />

1 Département de Génétique, CHU le Bocage, DIJON, France, 2 Laboratoire<br />

d’Anatomopathologie, CHU le Bocage, DIJON, France, 3 Maternité, CHU le<br />

Bocage, DIJON, France.<br />

The importance <strong>of</strong> array-based comparative genomic hybridization<br />

(aCGH) for detecting unbalanced genomic aberrations including microdeletions,<br />

duplications and subtelomeric rearrangements have<br />

been largely demonstrated in postnatal series. We analyzed a series<br />

<strong>of</strong> 25 fetuses using aCGH (IntegraChip) with at least three malformations<br />

and normal karyotype. Fetal DNA was extracted from frozen<br />

sample and analyzed with 1-Mb BAC-arrays, including 4898 clones<br />

with a resolution <strong>of</strong> 600 kilobases. A genomic disorder was found in<br />

2/25 fetus (8%), both confirmed by FISH analysis. The first case was<br />

a fetus with a de novo 15q26qter deletion (7.2Mb) associated with a<br />

phenotype compatible with Fryns syndrome: congenital diaphragmatic<br />

hernia (CDH), dysmorphic features, cardiac abnormality (aortic stenosis<br />

and hypoplasia left cavities) and hypoplastic distal phalanges.<br />

The deletion overlaps the critical region <strong>of</strong> CDH in 15q26.1q26.2. The<br />

second fetus presented de novo 13q32.2qter deletion (14Mb) associated<br />

with growth retardation, crani<strong>of</strong>acial dysmorphism, foot anomalies<br />

(clubfeet) and hypoplastic kidneys. This study demonstrates the utility<br />

<strong>of</strong> the array-CGH technology in detecting chromosomal abnormality<br />

in fetuses, allowing genetic counselling for the family. Observation 1<br />

can also be <strong>of</strong> interest since it could be a clue in the search for the<br />

genes responsible for Fryns syndrome. The detection rate in our series<br />

is comparable with the two studies <strong>of</strong> fetuses with malformations<br />

analysed with BACs-array 300 and 3500 clones (8% and 7.3 % after<br />

exclusion <strong>of</strong> inherited anomalies) [Le Caignec et al., 2005; Schaeffer<br />

et al., 2004].<br />

P03.087<br />

Detection <strong>of</strong> known microdeletion syndromes on array-cGH:<br />

when the boundaries <strong>of</strong> clinical diagnoses are reached.<br />

S. Bouquillon 1 , J. Andrieux 2 , C. Vincent-Delorme 1 , O. Boute-Bénéjean 1 , S. Joriot<br />

3 , J. Cuisset 3 , S. Auvin 4 , G. Plessis 5 , B. Delobel 6 , S. Manouvrier-Hanu 1 , M.<br />

Holder-Espinasse 1 ;<br />

1 Génétique Clinique, hôpital Jeanne de Flandre, Lille, France, 2 Laboratoire<br />

de Génétique Médicale, hôpital Jeanne de Flandre, Lille, France, 3 Neurologie<br />

pédiatrique, hôpital Roger Salengro, Lille, France, 4 Neurologie pédiatrique,<br />

hôpital Robert Debré, Paris, France, 5 Département de Génétique, CHU hôpital<br />

Clémenceau, Caen, France, 6 Centre de génétique chromosomique, hôpital<br />

Saint Vincent de Paul, Lille, France.<br />

The majority <strong>of</strong> recognizable syndromes had already been well described<br />

in their typical clinical presentations before classical recurring<br />

microdeletions were identified. The limited resolution <strong>of</strong> the conventional<br />

cytogenetics still fails to detect submicroscopic chromosomal<br />

imbalances. Therefore, suggestive phenotypes lead to targeted Fluorescence<br />

Hybridization In Situ (FISH) that is the most appropriate<br />

approach to confirm the diagnosis. Conversely, an apparently “chromosomal”<br />

but not specific developmental disorder with normal conventional<br />

karyotype can benefit from a new comprehensive high-resolution<br />

approach: Array-Comparative Genomic Hybridization (Array-CGH). It<br />

can however be very disappointing for the clinician when a known microdeletion<br />

syndrome is diagnosed by this latter technique.<br />

In our experience, array-CGH identified ~15% chromosomal imbalances<br />

in about one thousand individuals presenting unexplained developmental<br />

disorders. Nine <strong>of</strong> them (0.9%) presented a known microdeletion<br />

syndrome not diagnosed on clinical findings. Three were<br />

terminal deletions (two 1pter and one 22qter) and 6 were typical interstitial<br />

deletions (3 Di-George, 1 Smith-Magenis, 1 Angelman and 1<br />

Williams-Beuren syndromes).<br />

We present some representative examples and propose hypotheses<br />

to explain the misdiagnoses:<br />

- The phenotype can be atypical in particular for syndromes with important<br />

clinical variability such as 22q11.2 deletion<br />

- The analysis <strong>of</strong> the dysmorphic features may be difficult when the<br />

patient is adult<br />

- Some recently identified syndromes such as 22qter deletion may be<br />

“missed” by some clinicians<br />

- The phenotype can be suggestive but associated with rare or none<br />

previously reported features.<br />

P03.088<br />

Whole-genome array-cGH screening in undiagnosed syndromic<br />

patients: old syndromes revisited.<br />

A. Mosca 1 , P. Callier 1 , L. Faivre 2 , N. Marle 1 , C. Thauvin-Robinet 2 , A. Masurel-<br />

Paulet 2 , M. Beri 3 , E. Pipiras 4 , A. Delahaye 4 , E. Questiaux 5 , B. Benzacken 4 , P.<br />

Jonveaux 3 , F. Mugneret 1 ;<br />

1 Laboratoire de Cytogénétique, Dijon, France, 2 Centre de Génétique, Dijon,<br />

France, 3 Laboratoire de Cytogénétique, Nancy, France, 4 Laboratoire de Cytogénétique,<br />

Hôpital Jean-Verdier, Paris, France, 5 Centre de Génétique, Hôpital<br />

Robert Ballanger, Aulnay sous bois, France.<br />

Most microdeletional syndromes were presumed to be well defined<br />

clinical entities. However, the introduction <strong>of</strong> whole-genome screening<br />

led not only to the description <strong>of</strong> new syndromes, but also to the recognition<br />

<strong>of</strong> a broader spectrum <strong>of</strong> features for well-known syndromes.<br />

Here we report on 3 patients presenting with mental retardation and<br />

normal standard karyotype. Patient 1 was a 37 year-old male with pr<strong>of</strong>ound<br />

mental retardation, severe psychiatric disturbances within the<br />

autism spectrum, non-specific dysmorphic features and bilateral retinal<br />

detachment. 105K array-CGH Agilent permitted to diagnose a 1.6<br />

Mb 17p11.2 microdeletion including the RAI1 gene, smaller than the<br />

common microdeletion usually found in Smith-Magenis syndrome. Patient<br />

2 was a 31-year-old female with mild mental retardation, severe<br />

anxiety, non-specific dysmorphic features and short stature with micromelia<br />

(142 cm) and X-rays compatible with hypochondroplasia. 105K<br />

array-CGH Agilent revealed a 1.4 Mb 7q11.23 microdeletion, similar to<br />

the deletion found in Williams syndrome. Patient 3 was a 6-year-old<br />

boy with mild mental retardation, non-specific facial dysmorphism and<br />

autistic features. BAC-array (Integragen, 1Mb) also revealed a 7q11.23<br />

microdeletion including the ELN gene. Reevaluation in the 3 patients<br />

confirmed that the diagnosis was not possible on clinical grounds and<br />

emphasize that well-known genomic disorders can be phenotypically<br />

heterogeneous and more variable than originally thought. The large<br />

use <strong>of</strong> array-CGH might lead that such patients may be more readily<br />

achieved on the basis <strong>of</strong> genotype rather than phenotype.<br />

P03.089<br />

44K array-cGH in 1000 patients presenting mental retardation/<br />

multiple congenital malformations.<br />

J. R. Andrieux1 , M. Holder-Espinasse2 , O. Boute-Benejean2 , A. Dieux-Coeslier2<br />

, M. Mathieu3 , G. Morin3 , B. Demeer3 , H. Copin3 , L. Vallée4 , B. Delobel5 , B.<br />

Duban-Bedu5 , G. Plessis6 , M. Kottler6 , C. Vincent-Delorme2 , S. Manouvrier-<br />

Hanu2 ;<br />

1 2 Laboratoire de Génétique Médicale, CHRU, Lille, France, Service de Génétique<br />

clinique, CHRU, Lille, France, 3Service de Génétique, CHU, Amiens,<br />

France, 4Service de Neuropédiatrie, CHRU, Lille, France, 5Centre de Génétique<br />

Chromosomique, GHICL, Lille, France, 6Service de Cytogénétique et de Génétique<br />

moléculaire, CHU, Caen, France.<br />

Since 2008, 11 array-CGH platforms have been enforced in France in<br />

order to detect constitutional cryptic genomic imbalances as a routine<br />

diagnosis.<br />

To date, 1000 DNAs from patients presenting with MR/MCA have been<br />

studied using Agilent 44K array-CGH in our centre: 914 post-natal<br />

cases and 86 prenatal cases (63 after termination <strong>of</strong> pregnancy and<br />

13 during pregnancy).<br />

Considering post-natal cases, 160 (17.5%) genomic imbalances have<br />

been detected: 128 (14%) were considered deleterious (i.e. de novo<br />

or transmitted from a parent showing the same phenotype), 13 (1.4%)<br />

were found in a healthy parent but for the remaining 19 (2.1%) no<br />

parental samples were available. For the prenatal cases, 15 (17.4%)<br />

genomic imbalances were detected: 12 (14%) were considered deleterious<br />

and 3 (3.5%) were identified in a healthy parent.<br />

Among the 140 deleterious genomic imbalances:<br />

- 11 (7.9%) corresponded to known microdeletion syndrome not diagnosed<br />

on clinical findings: 3 were telomeric (two 1pter and one 22qter)<br />

and 6 were typical interstitial (three del 22q11.2 (DiGeorge), one del<br />

17p11.2 (SMS), one del 15q11.2 (Angelman syndrome), one 7q11.23<br />

(Williams-Beuren)). Two were Xq28 duplications involving MECP2.<br />

- 4 (2.9%) were imbalanced telomeric anomalies (partial monosomy<br />

associated with partial trisomy).<br />

- 23 patients presented new microdeletion syndromes. Three del<br />

17q21 (MAPT), 3 del 15q13.3 (CHRNA7), 6 del 1q21/3 dup 1q21 (microcephaly/macrocephaly),<br />

and 4 del 16p11.2/7 dup 16p11.2.<br />

- 5 patients presented single gene deletions.<br />

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