José Carlos Cabral de Almeida

Prenatal exposure to misoprostol and vascular disruption defects: A case-control study

Prenatal exposure to misoprostol has been associated with Moebius and limb defects. Vascular disruption has been proposed as the mechanism for these teratogenic effects. The present study is a multicenter, case-control study that was designed to compare the frequency of prenatal misoprostol use between mothers of Brazilian children diagnosed with vascular disruption defects and matched control mothers of children diagnosed with other types of defects. A total of 93 cases and 279 controls were recruited in eight participating centers. Prenatal exposure was identified in 32 infants diagnosed with vascular disruption defects (34.4%) compared with only 12 (4.3%) in the control group (P<0.0000001). Our data suggest that prenatal exposure to misoprostol is associated to the occurrence of vascular disruption defects in the newborns.

Xp-duplications with and without sex reversal

Duplications in Xp including the DSS (dosage sensitive sex reversal) region cause male to female sex reversal. We investigated two patients from families with Xp duplications. The first case was one of two sisters with karyotype 46,XY, der(22), t(X;22)(p11.3;p11)mat and unambiguous female genitalia. The living sister was developmentally retarded, and showed multiple dysmorphic features and an acrocallosal syndrome. The second case was a boy with a maternally inherited direct duplication of Xp21.3-pter with the breakpoint close to the DSS locus. He had multiple abnormalities and micropenis, but otherwise unambiguous male genitalia. We performed quantitative Southern blot analysis with probes from Xp22.13 to p21.2 to define the duplicated region. Clinical, cytogenetic, and molecular data from both patients were compared with those of previously reported related cases. A comparison of the extragenital symptoms revealed no differences between patients with or without sex reversal. In both cases, the symptoms were non-specific. Among 22 patients with a duplication in Xp, nine had unambiguous female genitalia and a well-documented duplication of the DSS region. Two patients with duplication of DSS showed ambiguous external genitalia. From these data, we conclude that induction of testicular tissue may start in these patients, but that the type of genitalia depends on the degree of subsequent degeneration by a gene in DSS.

Investigação clínica e genética em meninas com baixa estatura idiopática

Ten girls with idiopathic short stature (ISS) were clinically reviewed and cytogenetic analysis performed by GTG-banding. Two abnormal karyotypes were identified: mos 45,X/46,XX and mos 45,X/46,X, der(Xp)/46,X,r(X). In the latter, FISH analysis and microsatellite investigation, including intragenic SHOX CA repeat, confirmed the origin of the abnormal structural chromosomes and revealed haploinsufficiency for the SHOX gene. In the remaining 8 patients with a normal lymphocyte karyotype FISH analysis using an alpha centromeric X probe (DXZ1) in buccal smear cells (nuc ish) revealed two further cases of true X mosaicism (DXZ1x2/DXZ1x1). Clinical review of all four abnormal patients with the exception of patient with mos 45,X/46,XX revealed three or more clinical features commonly present in Turner syndrome (TS). Our results reinforce the importance of cytogenetic investigation in all patients with ISS. The SHOX molecular result sustains its correlation with most clinical signs of TS. In those cases where a normal karyotype was observed, cryptic mosaicism should be excluded. A precise etiologic diagnosis may be relevant for the indication of GH therapy in these girls.

Constitutional and somatic methylation status of DMRH19 and KvDMR in Wilms tumor patients

The most frequent epigenetic alterations in Wilms tumor (WT) occur at WT2, assigned to 11p15. WT2 consists of two domains: telomeric domain 1 (DMRH19) that contains the IGF2 gene and an imprinted maternally expressed transcript (H19) and centromeric domain 2 (KvDMR) that contains the genes KCNQ1, KCNQ1OT1 and CDKN1C. In this work, we used pyrosequencing and MS-MLPA to compare the methylation patterns of DMRH19/KvDMR in blood and tumor samples from 40 WT patients. Normal constitutional KvDMR methylation indicated that most of the epigenetic alterations in WT occur at DMRH19. Constitutional DMRH19 hypermethylation (HM DMRH19) was observed in two patients with Beckwith-Wiedemann syndrome. Pyrosequencing and MS-MLPA showed HM DMRH19 in 28/34 tumor samples: 16/34 with isolated HM DMRH19 and 12/34 with concomitant HM DMRH19 and KvDMR hypomethylation, indicating paternal uniparental disomy. With the exception of one blood sample, the MS-MLPA and pyrosequencing findings were concordant. Diffuse or focal anaplasia was present in five tumor samples and was associated with isolated somatic HM DMRH19 in four of them. Constitutional 11p15 methylation abnormalities were present in 5% of the samples and somatic abnormalities in the majority of tumors. Combined analysis of DMRH19/KvDMR by pyrosequencing and MS-MLPA is beneficial for characterizing epigenetic anomalies in WT, and MS-MLPA is useful and reliable for estimation of DNA methylation in a clinical setting.

Cytogenetic and molecular studies of an X;21 translocation previously diagnosed as complete monosomy 21

We studied a child with apparent monosomy of chromosome 21. Cytogenetic, FISH and microsatellite analyses revealed a 45,X,-21,+der(X)t(X;21)(q25;q21.1) karyotype resulting from a de novo, unbalanced, X;21 non-reciprocal translocation of paternal origin, with partial monosomy of chromosomes 21 and X. An extreme, skewed X-inactivation pattern of the der(X) chromosome was demonstrated. Skewed inactivation probably accounted for a mild phenotype with respect to Xq25-->qter deletion while propagation of inactivation to the adjacent 21q region may account for mild clinical features associated to distal 21q monosomy.