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2008 Barcelona - European Society of Human Genetics

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Cytogenetics<br />

P02.096<br />

Delineation <strong>of</strong> a critical Region on chromosome 18 for the<br />

del(18)(q12.2q21.1) syndrome<br />

K. Buysse 1 , B. Menten 1 , A. Oostra 2 , S. Tavernier 3 , G. R. Mortier 1 , F. Speleman 1 ;<br />

1 Center for Medical <strong>Genetics</strong>, Ghent University Hospital, Ghent, Belgium, 2 Center<br />

for Developmental Disorders, Ghent University Hospital, Ghent, Belgium,<br />

3 M.P.I.G.O. ‘t Vurstjen, Evergem, Belgium.<br />

Array CGH has been instrumental in the identification <strong>of</strong> submicroscopic<br />

chromosomal aberrations leading to mental retardation and congenital<br />

abnormalities (MR/MCA), the delineation <strong>of</strong> new microdeletion<br />

syndromes and the identification <strong>of</strong> genes implicated in MR/MCA syndromes<br />

. An important step prior to assigning particular phenotypic features<br />

to particular genes is the delineation <strong>of</strong> critical regions for these<br />

specific clinical features. To this purpose, smaller interstitial deletions<br />

can be particularly important. In some syndromes, haploinsufficiency<br />

<strong>of</strong> a single gene appears to be responsible for most <strong>of</strong> the phenotypic<br />

features, as is the case for the EHMT1 gene in the 9q34 subtelomeric<br />

deletion syndrome . In contrast to distal 18q deletions, proximal interstitial<br />

deletions encompassing chromosome band 18q12 .3 and parts <strong>of</strong><br />

neighboring bands (q12.2→q21.1) have been reported less frequently.<br />

Up to now, 24 patients carrying such deletions were described . Accurate<br />

genotype-phenotype correlations are only possible for those<br />

cases for which breakpoints have been molecularly defined.<br />

Here we describe a boy with a submicroscopic deletion <strong>of</strong> less than 1 .8<br />

Mb <strong>of</strong> subband 18q12 .3 . The phenotypic features <strong>of</strong> the proband correspond<br />

well with those observed in patients with larger cytogenetically<br />

detectable deletions encompassing chromosome band 18q12 .3 . The<br />

deletion has been characterized at the molecular level which is important<br />

for defining small regions and eventually specific genes associated<br />

with specific phenotypic features. The deletion enabled us to define<br />

a critical region for the following features <strong>of</strong> the del(18)(q12 .2q21 .1)<br />

syndrome: hypotonia, expressive language delay, short stature and<br />

behavioral problems .<br />

P02.097<br />

A novel sex determining locus in a 46,XX-sRY negative sex<br />

reversal patient carrying a t(8;19)(q22.1;q13.1)<br />

N. Najera, J. Berumen, S. K<strong>of</strong>man, J. Perez, G. Queipo;<br />

Hospital General de Mexico/Facultad de Medicina, Mexico City, Mexico.<br />

The sex determining genes SRY and SOX9 are required to initiate<br />

and maintain testicular development . However, genetic interactions<br />

controlling the earliest steps in gonadal development remain poorly<br />

understood . The molecular abnormalities underlying a high proportion<br />

<strong>of</strong> XX maleness remain undiscovered . Using <strong>of</strong> high density SNP array<br />

in sex reversal patients could be useful to characterize the etiology<br />

<strong>of</strong> the abnormal gonadal development and provide new molecular<br />

insights into the normal regulatory network in the testis and ovary<br />

development . We performed SNPs microarray genotyping (Affymetrix<br />

geneChip 500k) to investigate homozygosity mapping and LOH in a<br />

nuclear family (mother, father, siblings) <strong>of</strong> a 46,XX-SRY negative male<br />

carrying a t(8;19)(q22 .1;q13 .1) . In addition we analyzed 10 sporadic<br />

SRY negative XX male . The results were also compared with the International<br />

HapMap . The analysis <strong>of</strong> the break points in the patient<br />

revealed in chromosome 19 three intervals with 59, 89, 25 and 15<br />

homozygous SNPs and three regions containing 83, 73 and 57 LOH<br />

SNPs located in chromosome 8 . Analysis <strong>of</strong> the data revealed four sex<br />

determining genes candidates, we present and discuss the genomic<br />

data and the analysis performed in order to identify a novel locus involved<br />

in the testicular development in humans .<br />

P02.098<br />

Prenatally diagnosed recombinant <strong>of</strong>fsprings resulting from<br />

adjacent-1, adjacent-2, 3:1 segregation modes <strong>of</strong> reciprocal<br />

translocations:fish and cytogenetic studies<br />

O. Sezer, F. Ekici, B. Ozyilmaz, M. Tosun, M. Ceyhan, O. Aydın, I. Kocak, G.<br />

Ogur;<br />

Ondokuz Mayis University Medical Faculty, Samsun, Turkey.<br />

Balanced translocation carriers can have recombinant <strong>of</strong>fsprings due<br />

to adjacent-1, adjacent-2, 3:1 and 4:0 segregation modes . Here, we<br />

report three prenatally diagnosed recombinant fetuses resulting from<br />

balanced parental translocations .<br />

Case1:Amniocentesis was performed because <strong>of</strong> bilateral choroid<br />

plexus cysts and hyperechogenic bowel . Fetal karyotype showed a de-<br />

rivative chromosome 1p[46,XY,der(1)t(1;?)(p36,1;?)] which was paternally<br />

originated:46,XY,t(1;8) (p36,1;p21,3)]. FISH confirmed translocation<br />

between chromosomes 1 and 8; fetal karyotype was interpreted as<br />

partial monosomy 1p/partial trisomy 8p . Adjacent-1 segregation mode<br />

was suggested . Parents decided to terminate the pregnancy . Fetus<br />

presented facial dysmorphism, limb abnormalities, cerebellar hypoplasia,<br />

ventriculomegaly, bilateral choroid plexus cysts, lung defects .<br />

Case2:Amniocentesis was performed due to fetal abnormalities: cleft<br />

lip/palate, tetralogy <strong>of</strong> fallot, ASD, single artery/vein <strong>of</strong> umbilical cord .<br />

Cytogenetics revealed unbalanced chromosomal translocation:46,XY,<br />

der(15)t(10;15) (q22,2;q11,2), paternally derived [46,XY,t(10;15)(q22,2<br />

;q11,2)] . Adjacent-2 segregation mode was suggested . FISH analysis<br />

confirmed der(15)t(10;15). Pregnancy ended spontaneously after amniocentesis<br />

. The fetus couldn’t be investigated .<br />

Case3:Amniocentesis was performed because <strong>of</strong> positive maternal<br />

serum triple screening . Cytogenetics revealed a surnumerary<br />

chromosome(47,XY,+mar) . Parents were karyotyped . The mother<br />

showed balanced reciprocal translocation:t(2;14)(p23;q23) . Surnumerary<br />

chromosome was identified as part <strong>of</strong> chromosome 14 (FISH<br />

analysis) . Fetal karyotype was interpreted as:47,XY,+der(14)t(2;14)(p<br />

23;q23)mat; partial trisomy 2p/partial trisomy 14q due to 3:1 segregation<br />

was suggested . Pregnancy was terminated . Extensive clinical<br />

evaluation showed fetal dysmorphism and open cranial sutures .<br />

P02.099<br />

male pseudohermaphroditism: a case report<br />

N. Andreescu, V. Belengeanu, D. Stoicanescu, S. Farcas, C. Popa, M. Stoian;<br />

University <strong>of</strong> Medicine and Pharmacy “Victor Babes”, Timisoara, Romania.<br />

Male pseudohermaphroditism is characterized by the presence <strong>of</strong> 46,<br />

XY karyotype, exclusively male gonads and ambiguous or female external<br />

and/or internal genitalia, caused by incomplete virilization during<br />

prenatal life . We report the case <strong>of</strong> an infant, in whom physical<br />

examination showed ambiguous external genitalia and some dysmorphic<br />

features . Cytogenetic investigation was performed for the correct<br />

assignment <strong>of</strong> the gender and chromosome analysis in blood lymphocytes<br />

revealed male genetic sex . The ambivalent aspect <strong>of</strong> the external<br />

genitalia, the gonads that are exclusively testes together with<br />

the result <strong>of</strong> the cytogenetic analysis showing male genetic sex, led<br />

to the diagnosis <strong>of</strong> male pseudohermaphroditism . A multidisciplinary<br />

approach involving pediatricians, specialists in the field <strong>of</strong> endocrinology,<br />

genetics, surgery and psychiatry is necessary in order to reach<br />

a prompt and correct diagnosis and treatment . In conclusion, careful<br />

examination <strong>of</strong> the external genitalia <strong>of</strong> every newborn should be systematic<br />

. Early diagnosis <strong>of</strong> a disorder <strong>of</strong> sexual development is <strong>of</strong> great<br />

importance as is the appropriate gender assignment . The most important<br />

decision will be the choice <strong>of</strong> sex assignment, which will depend<br />

on many complex factors . Birth registration should be postponed until<br />

the diagnostic evaluation enables the most appropriate choice <strong>of</strong> sex<br />

for rearing . The clinical management will help the child and the family<br />

deal effectively with this disorder .<br />

P02.100<br />

PcR based technique for sex selection in cattle<br />

E. Arbabai1 , F. Mahjoubi1 , M. Eskandainasab2 , M. Montazeri1 ;<br />

1 2 NRCGEB, Tehran, Islamic Republic <strong>of</strong> Iran, Zanjan university, Tehran, Islamic<br />

Republic <strong>of</strong> Iran.<br />

Embryo sexing is an important way for sex selection <strong>of</strong> <strong>of</strong>fspring . This<br />

is a potential method to considerably improve animal breeding and the<br />

efficiency <strong>of</strong> dairy and meat production. A novel repeated sequence<br />

specific to male cattle has been identified and named S4. S4 is a 1/5<br />

Kb repeating unit and which also contains various internal repeated<br />

sequence . S4 is localized on the long arm <strong>of</strong> the Y chromosome in the<br />

region <strong>of</strong> ZFY genes .<br />

Aim: The objective <strong>of</strong> this study is to identify embryo sexing by a simple<br />

and precise PCR method .<br />

Materials and Methods: Genomic DNA was extracted from the whole<br />

blood samples. Two sets <strong>of</strong> specific primers were designed<br />

Result: By this PCR based methods we could differentiate between<br />

female and male genomic DNA .<br />

Discussion: With this technique we can distinct males from females .<br />

This method has the potential to be employed for embryonic sex selection<br />

.

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