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A 19-week stillborn female fetus with bilateral cleft palate, horseshoe kidney, bicornuate uterus, low-set ears, and intrauterine growth retardation (IUGR) was found to have a supernumerary derivative chromosome 9 (der(9)) with an apparent tandem duplication in the long arm. PCR analysis at five polymorphic loci confirmed the duplication and showed an adjacent deletion, while whole chromosome FISH demonstrated only chromosome 9 to be involved. Further FISH studies of der(9) found the 9qh region to be duplicated, telomeric sequences to be intact, and subtelomeric sequences to be absent. Thus, the fetus was determined to be trisomic for 9pter→9q12 and 9q34.3→9qter, tetrasomic for 9q12→ 9q33, and disomic for 9q33→9q34.3. These results are consistent with a tandem duplication of 9q12→9q33 and adjacent distal deletion as designated by the karyotype, 47,XX,+der(9)dup(9)(q12q33)del(9) (q33q34.3).ish der(9)(WCP9+,D9Z1x2,STP9q-, AHT+) de novo. In addition to characterizing der(9), the combined PCR and cytogenetic studies refined the Genome Database Map of three loci (D9S907, D9S155, and D9S302) approximately to the distal 9q33 region. Without the attempt to refine breakpoints by PCR analysis, the deletion in distal 9q would not have been detected. Tandem direct duplication/deletion chromosomes have been reported in fewer cases than inverted duplication/deletions. We propose mechanisms of origin, consistent with those for recurrent inter stitial microdeletion and microduplication syndromes, shown to arise by recombination at homologous, flanking DNA sequences. Am. J. Med. Genet. 93:305–312, 2000. © 2000 Wiley-Liss, Inc.

Purpose: To evaluate the assumptions on which the American College of Medical Genetics (ACMG) Standards and Guidelines for detecting mosaicism in amniotic fluid cultures are based.Methods: Data from 653 cases of amniotic fluid mosaicism were collected from 26 laboratories. A chi-square goodness-of-fit test was used to compare the observed number of mosaic cases with the expected number based on binomial distribution theory.Results: Comparison of observed data from the in situ colony cases with the expected distribution of cases detected based on the binomial distribution did not reveal a significant difference (P = 0.525).Conclusions: The empirical data fit the binomial distribution. Therefore, binomial theory can be used as an initial discussion point for determining whether ACMG Standards and Guidelines are adequate for detecting mosaicism.

Culture of a mixture of bone marrow cells with and without T6 chromosome marker in diffusion chambers in mice yielded colonies (CFU-DG) containing cells of a single karyotype, suggesting clonality. Injection of individual CFU-DG colonies into lethally irradiated mice resulted in increased spleen colony formation on day 12 (CFU-S). The possibility of endogenous origin was excluded by demonstrating the presence of T6 marker in both CFU-DG and CFU-S colonies in karyotypically normal hosts. These findings suggest that the cells giving rise to granulocytic colonies in diffusion chambers also can give rise to multipotential hemopoietic cells.

Heart fatty acid binding protein (hFABP) is an abundant 14-kDa cytosolic protein thought to be involved in trafficking of fatty acids from the plasma membrane to sites of ß-oxidation in mitochondria and peroxisomes and to the endoplasmic reticulum for lipid synthesis. A human hFABP cDNA isolated by polymerase chain reaction was used as a probe for in situ hybridization to metaphase chromosomes. A fragment of the gene for human hFABP was used as a probe for fluorescence in situ hybridization to metaphase chromosomes. The cDNA and genomic probes both localized the gene for human hFABP to chromosome 1p32-1p33.

A ring chromosome No. 13 was found in a 21-year-old female with multiple anomalies suggestive of 13q-syndrome. Chromosomes of the girl and her parents, studied by quinacrine staining, revealed the ring to be of paternal origin. Detailed study of the quinacrine banding pattern of the ring indicated loss of the most distal band of the long arm (13q34) and possible partial loss of the next adjacent long arm band (13q33). The short arm (13q11) was present but the stalk (13p12) and satellite (13p13) regions appeared to be missing.

The Giemsa-11 technique specifically stains the secondary constriction region of chromosome 9. We report cytologic evidence for 9p trisomy in a 4 $$4{\raise0.5ex\hbox{$\scriptstyle 1$}\kern-0.1em/\kern-0.15em\lower0.25ex\hbox{$\scriptstyle 2$}}$$ -year-old girl with moderate retardation and multiple anomalies, using the Giemsa-11 technique.

A technique is described in detail for 1. differentially denaturing DNA along chromosome arms with sodium hydroxide containing formalin (NaOH-F) and 2. staining with acridine orange (AO). The NaOH-F/AO technique results in chromosomes with red, yellow, brown and green colored bands which, when photographed in black and white, appear to be the reverse of Q bands. Densitometry tracings of these patterns confirm them to be the reverse of Q bands with the exception of some centromeric regions and the secondary constrictions on chromosomes 1, 9 and 16.

• A patient with multiple exostoses, mental retardation, and unusual fades has an interstitial deletion of the long arm of chromosome 8, or 46,XX, del (8) (pter → q22::q24.1 → qter). She has some features of the Langer-Giedion syndrome, but her facies are not characteristic and she does not have cone-shaped phalangeal epiphyses. Of the eight previous reports of partial deletion of the long arm of chromosome 8, four patients had exostoses and unusual facies, three of whom had characteristics of the Langer-Giedion syndrome. The deleted segments in the patients with exostoses are not identical, although there are areas of deletion that are seen in more than one patient. Among the explanations of the relationship of the 8q deletions to exostoses is the presence of several loci on 8q that are involved in bone formation, the deletion of any of which may give rise to a similar skeletal defect.(Am J Dis Child 1983;137:444-448)

We report two brothers and two second cousins with 4p trisomy secondary to a familial translocation t(4;7) (pl2;q36). A comparison of their physical features demonstrates the variability of clinical manifestations associated with this chromosome abnormality. While previous authors have emphasized the distinctiveness of the 4p trisomy syndrome, the variability seen in the affected relatives in this family suggests that trisomy 4p is one of the less distinctive chromosomal syndromes. Further comparison of our patients with the previously reported cases of 4p trisomy and with two cases whose chromosomal breakpoints were similar confirms this variability. Studies of phenotype/karyotype correlations in affected relatives provides the best opportunity to determine the phenotypic consequences of a specific (that is, identical) translocation. Studies of unrelated persons are complicated by the effects of different breakpoints and of possible partial deletions.

Quinacrine fluorescent studies of sex chromatin in human neurons indicate that the distal portion of the Y chromosome is constantly seen in association with the nucleolus in the male. The degree of association between the “Y body” and the nucleolus in other cell types is much lower. The degree of association between the X chromatin and the nucleolus in human female neurons was also analyzed by this method, indicating the feasibility of studying both the X and Y chromatin in quinacrine-stained preparations of human neurons.