Prenatal BoBs™ is a robust technology for the investigation of fetuses with normal karyotype with or without sonographic abnormalities. Running in parallel with the karyotype analysis, it can be proposed instead of rapid FISH or QF-PCR providing rapid results on common aneuploidies and additional information regarding the microdeletion syndromes.

The gene coding for human anti-Müllerian hormone (AMH) was localized to subbands p13.2→p13.3 on chromosome 19, using in situ hybridization and Southern blot analysis of a panel of man-mouse and man-hamster somatic cell hybrids.

FOXC1 deletion, duplication, and mutations are associated with Axenfeld-Rieger anomaly, and Dandy-Walker malformation spectrum. We describe the clinical history, physical findings, and available brain imaging studies in three fetuses, two children, and one adult with 6p25 deletions encompassing FOXC1. Various combinations of ocular and cerebellar malformations were found. In all three fetuses, necropsy including detailed microscopic assessments of the eyes and brains showed ocular anterior segment dysgenesis suggestive of Axenfeld-Rieger anomaly. Five 6p25 deletions were terminal, including two derived from inherited reciprocal translocations; the remaining 6p25 deletion was interstitial. The size and breakpoints of these deletions were characterized using comparative genomic hybridization arrays. All six deletions included FOXC1. Our data confirm that FOXC1 haploinsufficiency plays a major role in the phenotype of patients with 6p25 deletions. Histopathological features of Axenfeld-Rieger anomaly were clearly identifiable before the beginning of the third-trimester of gestation.

Prenatal diagnosis of 4p deletion syndrome can be difficult, and it is the presence of prefrontal edema, associated with more subtle facial anomalies (short philtrum, microretrognathia) which should trigger cytogenetic investigation for 4p- deletion, even with only borderline growth retardation.

The major aneuploidies diagnosed prenatally involve the autosomes 13, 18, and 21, and sex chromosomes. Fluorescence in situ hybridization (FISH) allows rapid analysis of chromosome copy number in interphase cells. This prospective study evaluated the use of four commercially available centromeric DNA probes (DXZ1, DYZ1, D18Z1, and D13Z1/D21Z1) for direct analysis of uncultured amniocytes. One hundred and sixteen amniotic fluid samples were analysed by FISH and standard cytogenetics. This evaluation demonstrated that FISH with X, Y, and 18 alpha satellite DNA probes could accurately and rapidly detect aneuploidies involving these chromosomes and could be used in any prenatal clinical laboratory. In contrast, the 13/21 alpha satellite DNA probe hybridizing both chromosomes 13 and 21 was unreliable for prenatal diagnosis in uncultured amniocytes.

Small supernumerary marker chromosomes are present in about 0.05% of the human population. In approximately 28% of persons with these markers (excluding the approximately 60% derived from one of the acrocentric chromosomes), an abnormal phenotype is observed. We report on a 3-month-old girl with intrauterine growth retardation, craniofacial features, hypotonia, partial coloboma of iris and total anomalous pulmonary venous return. Cytogenetic analysis showed the presence of a supernumerary marker chromosome, identified by fluorescence in situ hybridization as part of chromosome 22, and conferring a proximal partial trisomy 22q22.21, not encompassing the DiGeorge critical region (RP11-154H4 + , TBX1-). This observation adds new information relevant to cat eye syndrome and partial trisomy of 22q.

A DNA probe derived from a mouse intronless pseudogene including coding regions for the myosin fast skeletal muscle alkali light chains, MLC1F/MLC3F (suggested HGM symbol, MYL1), was tested on a panel of 25 independent man-rodent somatic cell hybrids in order to assign the human MLC1F/MLC3F gene to a human chromosome. A 3.7-kb TaqI human fragment was found to correlate with the presence of chromosome 2 in the hybrids, characterized both by cytogenetic analysis and reference enzyme markers. A regional assignment to 2q32.1-qter was possible using hybrids whose human parental strains bore a reciprocal translocation t(X;2) (p22;q32.1). The fact that IDH1 and the MLC1F/MLC3F gene are closely linked on chromosome 1 in the mouse and map to the same region of human chromosome 2 in man indicates, that these chromosomes have a conserved region of homology between them and that the human 3.7-kb TaqI fragment corresponds indeed to a functional gene.

We report a case of fetal hyperechogenic bowel diagnosed at midgestation that was associated with fetal parvovirus B19 infection. Isolated hyperechogenic bowel was detected at 25 weeks. Cystic fibrosis, chromosomal abnormalities and cytomegalovirus infection were excluded, whereas polymerase chain reaction DNA for parvovirus B 19 was found positive on amniotic fluid. The hyperechogenic bowel decreased with complete resolution by 32 weeks of gestation. No other signs of fetal B19 infection were detected prenatally and the baby had normal postnatal outcome. This case provides additional arguments in favor of a possible intestinal tropism of parvovirus B19 during fetal life. Fetal B19 infection should be systematically incorporated in the prenatal evaluation of isolated fetal hyperechogenic bowel.