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 />
P03.174<br />
Deletion <strong>of</strong> the cHRNA7 gene in a patient with Prader-Willi<br />
syndrome and epilepsy<br />
A. Buffet1 , V. Gaston1 , B. Delobel2 , G. Diene3 , M. Tauber3 , P. Calvas1 , E. Bieth1 ;<br />
1 2 3 Hôpital Purpan, Toulouse, France, Hôpital Saint Vincent, Lille, France, Hôpital<br />
des Enfants, Toulouse, France.<br />
Prader-Willi syndrome (PWS) is an imprinting disorder caused by<br />
loss <strong>of</strong> expression <strong>of</strong> paternally inherited contiguous genes from the<br />
chromosomal region 15q11-q13. In 70 percent <strong>of</strong> cases the affected<br />
patients carry an interstitial deletion on the paternal chromosome 15.<br />
Two recurrent deletions are commonly reported: one between the<br />
breakpoint 1 (BP1) to BP3 and the other between BP2 to BP3. We<br />
have recently shown that approximately 10 percent <strong>of</strong> the 15q11-q13<br />
deletions are atypical and involve other breakpoints.<br />
PWS and epilepsy is a rare occurrence reported in less <strong>of</strong> 10 percent<br />
<strong>of</strong> PWS. Recent studies have shown that CHRNA7 gene (cholinergic<br />
receptor neuronal nicotinic alpha polypeptide 7) which maps on chromosome<br />
15q13.3 is involved in isolated epilepsy.<br />
We report a case <strong>of</strong> a young girl affected with PWS and epilepsy. PWS<br />
was suspected because <strong>of</strong> neonatal hypotonia and crani<strong>of</strong>acial feature.<br />
The diagnostic was confirmed by methylation analysis and an unbalanced<br />
karyotype 45,XX,-15,der(10)t(10;15)(q26.3;q13) was found<br />
by cytogenetics analysis. We performed a Quantitative Multiplex PCR<br />
Short Fluorescent fragment methodology to analyse ten markers <strong>of</strong><br />
the 15q11-q13 region including the CHRNA7 gene. We found a large<br />
atypical deletion leading to the loss <strong>of</strong> the CHRNA7 gene. Our results<br />
suggest that epilepsy in this case <strong>of</strong> PWS could be due to the haploinsufficiency<br />
<strong>of</strong> CHRNA7. At our knowledge, it is the first case <strong>of</strong><br />
PWS and epilepsy with a demonstrated deletion <strong>of</strong> CHRNA7 gene.<br />
We propose to search for an atypical deletion in all patients with PWS<br />
and epilepsy.<br />
P03.175<br />
Deletion analysis using Quantitative multiplex PcR <strong>of</strong> short<br />
fluorescent Fragments (QMPSF) in patients with Prader-Willi<br />
syndrome: evidence for uncommon deletion types<br />
V. Gaston 1 , A. Buffet 1 , G. Diene 2 , M. Tauber 2 , E. Bieth 1 ;<br />
1 Hôpital Purpan, Toulouse, France, 2 Hôpital des Enfants, Toulouse, France.<br />
Prader-Willi Syndrome (PWS) is a neurogenetic disorder that results<br />
from the absence <strong>of</strong> normally active paternally expressed genes from<br />
the 15q11-q13 chromosome region. About 70% <strong>of</strong> individuals have<br />
a paternally derived interstitial deletion <strong>of</strong> 15q11-q13. Two common<br />
classes <strong>of</strong> deletion has been reported: a type I between the breakpoint<br />
1 (BP1) to BP3 and a type II deletion between BP2 to BP3. The<br />
deletion type status is commonly characterized by FISH on cultured<br />
cells and/or by microsatellites analysis on both patient and parental<br />
DNA. Because these two approaches don’t allow the screening <strong>of</strong> the<br />
entire critical 15q11q13 region we believed that other types <strong>of</strong> deletion<br />
might be missed. We have recruited 66 PWS patients with routinely<br />
diagnosed 15q deletion and we have analyzed the critical region using<br />
a new molecular assay based on the QMPSF (Quantitative Multiplex<br />
PCR <strong>of</strong> Short fluorescent Fragments) method. This assay includes<br />
three multiplex PCR allowing amplification <strong>of</strong> 18 different gene-markers<br />
located from BP1 to telomeric to BP3 region. We found 16 PWS<br />
patients (24 %) with TI deletion, 44 (67 %) with TII deletion and 6 patients<br />
(9 %) carrying an uncommon 15q deletion. The ratio <strong>of</strong> TI/TII<br />
deletion was consistent with previous studies.<br />
In conclusion, our QMPSF assay represents a powerfull tool for rapid<br />
detection and characterization for small rearrangements in 15q11-q13<br />
region. It is particularly attractive to distinct different deletion types and<br />
useful for genotype-phenotype correlation studies in Prader-Willi syndrome.<br />
P03.176<br />
Evaluation <strong>of</strong> clinical findings in 17 Children with 22q11.2<br />
deletion syndrome with/without congenital hearth defects<br />
E. Mihci 1 , A. Uslu 2 , F. Kardelen 3 , S. Berker-Karaüzüm 4 , S. Taçoy 1 ;<br />
1 AkdenizUniversity School <strong>of</strong> Medicine Department <strong>of</strong> Pediatrics Division <strong>of</strong><br />
Clinical <strong>Genetics</strong>, Antalya, Turkey, 2 AkdenizUniversity School <strong>of</strong> Medicine Department<br />
<strong>of</strong> Pediatrics, Antalya, Turkey, 3 AkdenizUniversity School <strong>of</strong> Medicine<br />
Department <strong>of</strong> Pediatric Cardiology, Antalya, Turkey, 4 AkdenizUniversity School<br />
<strong>of</strong> Medicine Department <strong>of</strong> Medical Biology and <strong>Genetics</strong>, Antalya, Turkey.<br />
Deletion <strong>of</strong> chromosome 22q11.2 (22q11.2 DS) is one <strong>of</strong> the most<br />
common microdeletion syndromes. It is estimated incidence <strong>of</strong> 1:4000-<br />
5000 live births. Approximately, 22q11.2 DS accounts for 5 % all newborns<br />
with congenital heart diseases (CHD) and 75 % <strong>of</strong> patients with<br />
22q11.2 DS have CHD.The aim <strong>of</strong> this study was to evalute clinical<br />
findings in individuals with 22q11.2 DS. We retrospectively evaluated<br />
both clinical findings and CHD in 17 children with 22q11.2 DS. 10 cases<br />
had CHD with/without conotruncal defect and 7 cases had without<br />
CHD. Major dysmorphic fndings <strong>of</strong> the cases are hypertelorism, lateral<br />
displacement <strong>of</strong> the inner canthi, short palpebral fissures, swollen<br />
eyelids, dysmorphism <strong>of</strong> the nose, low set ears, minor ear-lobe<br />
anomalies and velopharyngeal insufficiency. We found that 12 cases<br />
had velopharyngeal insufficiency, 5 cases had hypocalsemia and one<br />
case with immune deficiency (Low T-cell level). Interestingly, we found<br />
that 3 cases (3/7) without CHD had dysmorphism <strong>of</strong> nose and all <strong>of</strong> the<br />
cases without CHD (7/7) had velopharyngeal insufficiency. But however<br />
only 5 case with CHD (5/10) had velopharyngeal insufficiency.In<br />
the study, we presented that dysmorphic features <strong>of</strong> 22q11.2 DS such<br />
as velopharyngeal insufficiency and dysmorphism <strong>of</strong> nose may be important<br />
sign for diagnosis <strong>of</strong> cases with 22q11.2 DS without CHD.<br />
P03.177<br />
DiGeorge syndrome presenting with laryngeal membrane<br />
D. Begović, S. Huljev Frković, R. Lasan Trčić, D. Markov Glavaš, D. Šarić, L.<br />
Letica;<br />
University Hospital Centre Zagreb, Zagreb, Croatia.<br />
We present a case <strong>of</strong> DiGeorge syndrome with laryngeal membrane<br />
as additional element <strong>of</strong> the syndrome. The patient is the first child <strong>of</strong><br />
healthy parents, male, born on term, spontaneously, BW 3730 gr, BL<br />
51 cm, HC 37 cm, Apgar 9/10. Within first minutes <strong>of</strong> life baby cryed<br />
without voice with occasional inspiratory stridor. Micrognatia, low set,<br />
small ears, hypertelorism, short palpebral fissures, blunted nose, short<br />
philtrum, high arched palate were also noticed. Endotracheal endoscopy<br />
showed omega epiglottis and laryngeal membrane occupying 50<br />
% <strong>of</strong> laryngeal entrance. Cardiac ultrasound showed ventricular septal<br />
defect, atrial septal defect type II and right aortal arch. Fluorescence in<br />
situ hybridistaion (FISH) analysis revealed a deletion <strong>of</strong> chromosome<br />
22q11.2.<br />
Although rarely, laryngeal membrane, especially in combination with<br />
congenital heart defects should be considered for deletion 22q11.2.<br />
P03.178<br />
A case <strong>of</strong> Emanuel syndrome arising from 2:2 segregation <strong>of</strong> a<br />
paternal t(11;22)<br />
A. M. Mohamed, A. K. Kamel, M. O. El Rouby, M. S. Zaki, H. A. Hussein;<br />
National Research cetre, Cairo, Egypt.<br />
Emanuel syndrome is an inherited chromosomal abnormality. It<br />
is the result <strong>of</strong> 3:1 meiotic segregation <strong>of</strong> a balanced translocation,<br />
t(11;22)(q23;q11). This rearrangement is the only recurrent non Robertsonian<br />
translocation in humans. Affected <strong>of</strong>fspring usually carry a<br />
supernumerary derivative 22 chromosome and thus effectively trisomic<br />
for part <strong>of</strong> chromosome 22 and part <strong>of</strong> chromosome 11.<br />
A 6 years female patient, presented with mental retardation, crani<strong>of</strong>acial<br />
abnormalities, with no cardiac abnormalities.<br />
Cytogenetic analysis and FISH using WCP11, WCP 22, LSI N25 and<br />
LSI 22q13.3 revealed that the child had both translocation chromosomes,<br />
plus an additional copy <strong>of</strong> der(22). Her father had balanced<br />
translocation t(11;22), also her brother had the same balanced translocation.<br />
Her karyotype was 47,t(11;22)(q23;q11),+der(22).This rare<br />
karyotype can arise by 2:2 segregation in 1 st meiotic division in the<br />
balanced translocation father, followed by nondisjunction at meiosis II<br />
in a balanced spermatocyte.<br />
Genetic counseling and prenatal diagnosis and awareness <strong>of</strong> high risk<br />
breast cancer is very important in the families with balanced carrier <strong>of</strong><br />
a t(11;22).<br />
P03.179<br />
three cases <strong>of</strong> two unrelated families with a microduplication<br />
22q11.2: developmental skull defects and phenotype variability.<br />
F. Ahlfors 1 , L. Grozdanova 2 , R. Stoeva 3,4 , J. Fryns 4 , T. Olausson 1 , P. Andersson<br />
1 , C. Darnfors 1 , M. Stefanova 1 ;<br />
1 Department <strong>of</strong> Clinical <strong>Genetics</strong>, Sahlgrenska University Hospital, Gothen-