DNA sequence and annotation of the entire human chromosome 7, encompassing nearly 158 million nucleotides of DNA and 1917 gene structures, are presented. To generate a higher order description, additional structural features such as imprinted genes, fragile sites, and segmental duplications were integrated at the level of the DNA sequence with medical genetic data, including 440 chromosome rearrangement breakpoints associated with disease. This approach enabled the discovery of candidate genes for developmental diseases including autism.

Amniotic fluid is a dynamic and complex mixture that reflects the physiological status of the developing fetus. In this study, the human amniotic fluid (AF) proteome of a 16 -18-week normal pregnancy was profiled and analyzed to investigate the composition and functions of this fluid. Due to the complexity of AF, we utilized three different fractionation strategies to provide greater coverage. Two types of two-dimensional LC/MS/MS as well as an LC-SDS-PAGE-LC-MS/MS platform were used. A total of 16 AF samples between gestational ages of 16 and 18 weeks from women carrying chromosomally normal fetuses were analyzed by one of the three fractionation methods followed by a common reverse phase LC-MS/MS step. Mascot and The Global Proteome Machine engines were used to search the International Protein Index human database for peptide sequence identification. The list of proteins was generated by combining the results of both engines through the PeptideProphet of Scaffold software. All identified proteins were combined to generate the AF proteome comprising 1,026 unique gene matches or 842 non-redundant proteins. This list includes most of the currently used biomarkers for pregnancy-associated pathologic conditions such as preterm delivery, intra-amniotic infection, and chromosomal anomalies of the fetus. The subcellular localization, tissue expression, functions, and networks of the AF proteome were analyzed by various bioinformatic tools. These data will contribute to the better understanding of amniotic fluid function and to the discovery of novel biomarkers for prenatal diagnosis of fetal abnormalities.

ObjectivesThe clinical outcome of prenatally diagnosed congenital heart defects (CHD)

Objective To report on the prenatal ultrasound findings in fetuses with lissencephaly associated with Miller-Dieker syndrome (MDS) and to compare these findings with those of magnetic resonance imaging (MRI). Methods

From January 1990 until December 1996, 212 cases of neural tube defect (NTD) were seen through the Prenatal Diagnosis Program of the University of Toronto. Of the 212 cases, 200 were karyotyped successfully and of these, 13 (6.5%) had chromosome abnormalities. When classified according to the site of the NTD, 2.3% (2/88) of anencephalics, 7.1% (1/14) of encephaloceles, and 10.2% (10/98) of meningomyeloceles had abnormal karyotypes. The absence of associated ultrasound abnormalities was not necessarily predictive of a chromosomally normal fetus; 4/167 (2.4%) of fetuses with isolated NTDs had chromosome abnormalities. Conversely, 24/33 (72%) of fetuses with additional findings on ultrasound had normal chromosomes. The diagnosis of a chromosome abnormality associated with NTD has important implications for recurrence risk and prenatal diagnosis, not only for the parents but potentially for other relatives. Based on our finding that 6.5% of prenatally detected NTDs are associated with chromosome abnormalities, we recommend karyotyping of all fetuses and/or newborns with NTD.

In a family in which a large pericentric inversion of chromosome 7 is segregating, two of the four progeny of inversion heterozygotes show severe psychomotor retardation and have the karyotype 46, XX, rec(7), dup q, inv(7)(p22q32), derived from crossing-over within the inversion. Meiotic analysis in one of the heterozygotes revealed no evidence of inversion loops in well-spread pachytene cells. In approximately 20 % of cells in diakinesis, the presumptive bivalent 7 had only one chiasma. Two alternatives to the reversed loop mode of meiotic pairing of inversions are proposed. Review of the literature supports the view that “small” pericentric inversions have a much better genetic prognosis than “large” pericentric inversions.

Supravalvular aortic stenosis may present as an isolated finding or as part of Williams syndrome. Williams syndrome is a contiguous gene syndrome associated with neurodevelopmental and multisystemic manifestations caused by hemizygous deletion at 7q11.23. We report on the prenatal and histopathological findings in a patient with a chromosome translocation involving the Williams syndrome critical region. The initial abnormality on fetal ultrasound was hydrops fetalis detected at 30 weeks and echocardiography showed narrowing of the aorta and the pulmonary arteries. The baby died shortly after delivery and an autopsy revealed diffuse tubular thickening with luminal narrowing of the aorta, aortic branches, and the pulmonary arteries. Histopathology showed dysplasia of the media with reduced elastic content and "cartwheel" arrangement of collagen, elastic, and muscle fascicles. The karyotype was 46,XX,t(6;7)(q27;q11.23). Three signals were detected using the Oncor fluorescent in situ hybridization probe for elastin-Williams syndrome (WSCR) suggesting that the break in chromosome 7 is within the elastin-Williams gene. This patient is of special interest because of the prenatal presentation and the chromosomal translocation involving the elastin-Williams syndrome locus.

Isochromosome (tetrasomy) 9p is a rare chromosomal aberration characterized by phenotypic abnormalities ranging from mild developmental delay to multiple anomalies including intrauterine growth retardation, cerebral ventriculomegaly, dysmorphic facial features, cleft lip or palate, abnormal genitalia and renal anomalies. We present a patient with isochromosome (tetrasomy) 9p mosaicism who is a healthy normal adult male with oligospermia who has fathered two normal children. This chromosomal abnormality may be tissue specific, with a higher detection rate in cultured lymphocytes compared with fibroblasts. Therefore, there is an increased chance of missing the abnormality prenatally by amniocentesis or chorionic villus sampling. We are aware of only one other patient in the literature with a normal phenotype associated with mosaicism for this chromosomal abnormality.