The 22q11.2 deletion was common in this birth population. The clinical phenotype included a wide and variable spectrum of major cardiac and extracardiac anomalies. From these population-based data, one can estimate that at least 700 affected infants are born annually in the United States. Population-based estimates such as these should be useful to medical professionals and policy makers in planning for the optimal care of people with the 22q11.2 deletion.

Although survival is greatly affected by trisomy 13 and trisomy 18, 5% to 10% of people with these conditions survive beyond the first year of life. These population-based data are useful to clinicians who care for patients with these trisomies or counsel families with infants or fetuses who have a diagnosis of trisomy 13 or 18.

Cultured mammalian cells are used extensively in cell biology studies. It requires a number of special skills in order to be able to preserve the structure, function, behavior, and biology of the cells in culture. This unit describes the basic skills required to maintain and preserve cell cultures: maintaining aseptic technique, preparing media with the appropriate characteristics, passaging, freezing and storage, recovering frozen stocks, and counting viable cells.

The deletion of chromosome 1p36 is a newly recognized, relatively common contiguous gene deletion syndrome with a variable phenotype. The clinical features have recently been delineated and molecular analysis indicates that the prevalence of certain phenotypic features appears to correlate with deletion size. Phenotype/genotype comparisons have allowed the assignment of certain clinical features to specific deletion intervals, significantly narrowing the regions within which to search for candidate genes. We have extensively characterized the deletion regions in 30 cases using microsatellite markers and fluorescence in situ hybridization analyses. The map order of 28 microsatellite markers spanning the deletion region was obtained by a combination of genotypic analysis and physical mapping. The deletion region was divided into six intervals and breakpoints were found to cluster in mainly two regions. Molecular analysis of the deletions showed that two patients had complex re-arrangements; these cases shared their distal and proximal breakpoints in the two common breakpoint regions. Of the de novo deletions ( n = 28) in whichparental samples were available and the analysis was informative ( n = 27), there were significantly morematernally derived deletions ( n = 21) than paternally derived deletions ( n = 6) (chi1(2) = 8.35, P < 0.0001). Phenotype/genotype correlations and refinements of critical regions in our naturally occurring deletion panel have delineated specific areas in which to focus the search for the causative genes for the features of this syndrome.

Purpose: Deletions of distal 9p are associated with trigonocephaly, mental retardation, dysmorphic facial features, cardiac anomalies, and abnormal genitalia. Previous studies identified a proposed critical region for the consensus phenotype in band 9p23, between 11.8 Mb and 16 Mb from the 9p telomere. Here we report 10 new patients with 9p deletions; 9 patients have clinical features consistent with 9pϪ syndrome, but possess terminal deletions smaller than most reported cases, whereas one individual lacks the 9pϪ phenotype and shows a 140-kb interstitial telomeric deletion inherited from his mother. Methods: We combined fluorescence in situ hybridization and microarray analyses to delineate the size of each deletion. Results: The deletion sizes vary from 800 kb to 12.4 Mb in our patients with clinically relevant phenotypes. Clinical evaluation and comparison showed little difference in physical features with regard to the deletion sizes. Severe speech and language impairment were observed in all patients with clinically relevant phenotypes. Conclusion: The smallest deleted region common to our patients who demonstrate a phenotype consistent with 9pϪ is Ͻ2 Mb of 9pter, which contains six known genes.These genes may contribute to some of the cardinal features of 9p deletion syndrome. Genet Med 2008:10 (8): 599 -611. Key Words: 9p deletion, FISH, genotype-phenotype correlation, aCGHThe 9p deletion syndrome is characterized by trigonocephaly, moderate to severe mental retardation, low-set, malformed ears, and dysmorphic facial features, such as up-slanting palpebral fissures and a long philtrum. 1,2 Furthermore, abnormal genitalia are found in some 9pϪ patients who have a chromosomal complement of 46, XY, 3 and hypopigmentation has also been described in two independent studies. 4,5 Since the original report of the syndrome in 1973, 6 over 140 cases of 9p deletion have been documented. The breakpoints occur in bands from 9p22 to 9p24, and the large majority of patients have either terminal deletions or translocations involving another chromosome.Previous studies have delineated the size of 9p deletions in an attempt to develop genotype-phenotype correlations. In one large study, Christ et al., 2 characterized the deletion breakpoints in 24 patients with visible 9p deletions and breakpoints at 9p22 or 9p23. Markers D9S274 (14.2 Mb from the telomere) and D9S286 (8 Mb) were absent in all 24 patients with 9pϪ, whereas D9S285 (16 Mb) was present in a subset of these patients. Thus, the minimal deleted segment in this group of patients included 16 Mb of the 9p terminus. Wagstaff and Hemann 4 described a patient with typical features of 9pϪsyndrome and an interstitial deletion between 8 Mb and 19 Mb of 9p. Based on the data of Wagstaff and Hemann, 4 and from their own data, Christ et al., 2 modified their critical region, i.e., the distal 16 Mb of 9p, and concluded that the critical region for the 9pϪsyndrome lies in an ϳ8-Mb region between D9S285 and D9S286, encompassing bands 9p22-9p23.Among a number of recent publicati...

Ten data sources were used substantially to increase the available data for estimating fetal and livebirth sex ratios for Patau (trisomy 13), Edwards (trisomy 18), and Down (trisomy 21) syndromes and controls. The fetal sex ratio estimate was 0.88 (N = 584) for trisomy 13, 0.90 (N = 1702) for trisomy 18, and 1.16 (N = 3154) for trisomy 21. All were significantly different from prenatal controls (1.07). The estimated ratios in prenatal controls were 1.28 (N = 1409) for CVSs and 1.06 (N = 49427) for amniocenteses, indicating a clear differential selection against males, mostly during the first half of fetal development. By contrast, there were no sex ratio differences for any of the trisomies when comparing gestational ages <16 and >16 weeks. The livebirth sex ratio estimate was 0.90 (N = 293) for trisomy 13, 0.63 (N = 497) for trisomy 18, and 1.15 (N = 6424) for trisomy 21, the latter two being statistically different than controls (1.05) (N = 3660707). These ratios for trisomies 13 and 18 were also statistically different than the ratio for trisomy 21. Only in trisomy 18 did the sex ratios in fetuses and livebirths differ, indicating a prenatal selection against males >16 weeks. No effects of maternal age or race were found on these estimates for any of the fetal or livebirth trisomies. Sex ratios for translocations and mosaics were also estimated for these aneuploids. Compared to previous estimates, these results are less extreme, most likely because of larger sample sizes and less sample bias. They support the hypothesis that these trisomy sex ratios are skewed at conception, or become so during embryonic development through differential intrauterine selection. The estimate for Down syndrome livebirths is also consistent with the hypothesis that its higher sex ratio is associated with paternal nondisjunction. © 1996 Wiley‐Liss, Inc.

Chromosome 15 (15q11-q13) abnormalities cause two distinct conditions, Angelman syndrome (AS) and Prader-Willi syndrome (PWS). We present the first case of a child with a balanced 15;15 translocation and AS in whom molecular studies were crucial in confirming a diagnosis. DNA polymorphisms demonstrated paternal uniparental disomy for chromosome 15, consistent with the diagnosis of AS. The molecular studies also showed the patient to be homozygous at all loci for which the father was heterozygous, suggesting that the structural rearrangement was an isochromosome 15q and not a Robertsonian translocation.

Cultured mammalian cells are used extensively in cell biology studies. It requires a number of special skills in order to be able to preserve the structure, function, behavior, and biology of the cells in culture. This unit describes the basic skills required to maintain and preserve cell cultures: maintaining aseptic technique, preparing media with the appropriate characteristics, passaging, freezing and storage, recovering frozen stocks, and counting viable cells. © 2016 by John Wiley & Sons, Inc.