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Coffin-Lowry syndrome (CLS) is an X-linked mental retardation syndrome caused by defects in the RSK2 gene. We have identified a CLS family with four patients in two generations. The patients in this family, a mother and her three children (a male and two females), all have severe mental retardation with the typical CLS phenotype. In addition, brain MRI studies on the three siblings revealed abnormalities in deep subcortical white matter, thinning of the corpus callosum, hypoplastic cerebellar vermis, and asymmetry of the lateral ventricles. The degree of severity of the MRI findings correlated with the severity of mental retardation in the patients. Extensive mutation screening was performed on the entire RSK2 gene in this family. Twenty-two exons including the intron/exon junctions were amplified by PCR and subsequently sequenced on both strands. A novel mutation, a two-nucleotide insertion (298 ins TG), was identified. The insertion creates a stop codon at codon 100, resulting in a 99 amino acid truncated RSK2 protein. All patients tested have the same mutation, and no other mutation could be found in the RSK2 gene from the proband. The mutation was confirmed by PCR/RFLP. X-chromosome inactivation assay on the female patients revealed significant skewing toward inactivation of the normal RSK2 allele. Thus, this novel mutation is likely to be responsible for the unusual clinical presentation in this family, which includes full phenotypic expression in females and unique brain MRI abnormalities. The pathological function of the mutation and genotype/phenotype correlation between the mutation and this unusual clinical presentation await further clarification., (Copyright 2006 Wiley-Liss, Inc.)

The immunodeficiency, centromeric region instability, facial anomalies (ICF) syndrome is a rare autosomal recessive disease. Usually, it is caused by mutations in the DNA methyltransferase 3B gene, which result in decreased methylation of satellite DNA in the juxtacentromeric heterochromatin at 1qh, 16qh, and 9qh. Satellite II-rich 1qh and 16qh display high frequencies of abnormalities in mitogen-stimulated ICF lymphocytes without these cells being prone to aneuploidy. Here we show that in lymphoblastoid cell lines from four ICF patients, there was increased colocalization of the hypomethylated 1qh and 16qh sequences in interphase, abnormal looping of pericentromeric DNA sequences at metaphase, formation of bridges at anaphase, chromosome 1 and 16 fragmentation at the telophase-interphase transition, and, in apoptotic cells, micronuclei with overrepresentation of chromosome 1 and 16 material. Another source of anaphase bridging in the ICF cells was random telomeric associations between chromosomes. Our results elucidate the mechanism of formation of ICF chromosome anomalies and suggest that 1qh-16qh associations in interphase can lead to disturbances of mitotic segregation, resulting in micronucleus formation and sometimes apoptosis. This can help explain why specific types of 1qh and 16qh rearrangements are not present at high frequencies in ICF lymphoid cells despite diverse 1qh and 16qh aberrations continuously being generated.

Squirrel monkeys are the most commonly used New World primates in biomedical research, but in vitro studies are restricted by the limited number of cell lines available from this species. We report here the development and characterization of a continuous, kidney epithelial cell line (SQMK-FP cells) derived from a newborn squirrel monkey. Karyotype was consistent with Bolivian squirrel monkey (submetacentric chromosome pair 15 and acrocentric chromosome pair 16). All cells examined were hyperdiploid with chromosome numbers ranging from 52 to 57. Ultrastructural analysis of SQMK-FP cells revealed the presence of cell junctions with radiating filaments, indicating desmosomes and numerous surface projections containing longitudinally oriented filaments typical of tubular epithelium. Biochemically, SQMK-FP cells exhibit glucocorticoid resistance typical of the squirrel monkey. Glucocorticoid receptor (GR) binding is low in SQMK-FP cells because of high expression of the FK506-binding immunophilin FKBP51 that inhibits GR binding. SQMK-FP cells constitute a tubular epithelial cell line that has biochemical properties characteristic of squirrel monkeys and represents an alternate cell model to B-lymphoblast SML cells to study the biology of the squirrel monkey in vitro.

A four-month-old white female, who was referred to us for genetic evaluation because of severe developmental delay, dysmorphic features, and bilateral cataracts, was found by routine cytogenetic analysis to have ring chromosome 16 in almost all cells analyzed. Ring chromosome 16 was confirmed and further delineated by fluorescence in situ hybridization (FISH). Breakpoints between loci D16S521 and KG8 on the short arm and D16S3121 and D16S303 on the long arm of chromosome 16 were determined by polymerase chain reaction (PCR) analysis. The deleted chromosome was of maternal origin. To our knowledge, this is the first case of ring chromosome 16 associated with bilateral cataracts. Comparison of previously reported cases with deletion of chromosome 16 and our case suggests the presence of cataract locus within 1 Mb of the terminus of 16q., (Copyright 2001 Wiley-Liss, Inc.)

Purpose: To illustrate the use of bacterial artificial chromosome (BAC) clone panels for molecular cytogenetic analysis of complex chromosome rearrangements (CCRs)., Methods: High resolution cytogenetics followed by fluorescence in situ hybridization (FISH) analysis using chromosome band-specific BAC probes, in addition to commercially available probes., Results: High resolution cytogenetics in conjunction with FISH using commercially available probes proved inadequate to resolve problems in characterizing a balanced CCR in the mother of a patient who had inherited an unbalanced form of the CCR. Accurate interpretation of the CCR and the unbalanced rearrangement in the patient as trisomy 7p12.2-->p21.3 was accomplished only through use of the BAC clone panel., Conclusion: Use of BAC clone panels can enhance the power of FISH analysis in defining chromosome rearrangements that cannot be resolved by high resolution chromosome analysis.

The squirrel monkey is a neotropical primate genus which is widely used in biomedical research but includes individual species and subspecies that respond differently to experimental perturbations. GTG-banding patterns of chromosomes 15 and 16, which are distinct among different squirrel monkey species and subspecies, were used to determine the origin of three lung fibroblast cell lines from squirrel monkeys of unknown genetic background (DPSO 114/74, SqMkLu/68, and 7603830) and to confirm the origin of a lymphoblast cell line (GSML) recently established from Guyanese squirrel monkey. DPSO 114/74 cells are from Peruvian squirrel monkey, SqMkLu/68 cells are Bolivian squirrel monkey, and 7603830 cells are from a Peruvian/Bolivian hybrid. Chromosome analysis of GSML cells confirmed that they are from Guyanese squirrel monkey., (Copyright 2001 S. Karger AG, Basel)

The ICF syndrome (immunodeficiency, centromeric region instability, facial anomalies) is a unique DNA methylation deficiency disease diagnosed by an extraordinary collection of chromosomal anomalies specifically in the vicinity of the centromeres of chromosomes 1 and 16 (Chr1 and Chr16) in mitogen-stimulated lymphocytes. These aberrations include decondensation of centromere-adjacent (qh) heterochromatin, multiradial chromosomes with up to 12 arms, and whole-arm deletions. We demonstrate that lymphoblastoid cell lines from two ICF patients exhibit these Chr1 and Chr16 anomalies in 61% of the cells and continuously generate 1qh or 16qh breaks. No other consistent chromosomal abnormality was seen except for various telomeric associations, which had not been previously noted in ICF cells. Surprisingly, multiradials composed of arms of both Chr1 and Chr16 were favored over homologous associations and cells containing multiradials with 3 or >4 arms almost always displayed losses or gains of Chr1 or Chr16 arms from the metaphase. Our results suggest that decondensation of 1qh and 16qh often leads to unresolved Holliday junctions, chromosome breakage, arm missegregation, and the formation of multiradials that may yield more stable chromosomal abnormalities, such as translocations. These cell lines maintained the abnormal hypomethylation in 1qh and 16qh seen in ICF tissues. The ICF-specific hypomethylation occurs in only a small percentage of the genome, e.g., ICF brain DNA had 7% less 5-methylcytosine than normal brain DNA. The ICF lymphoblastoid cell lines, therefore, retain not only the ICF-specific pattern of chromosome rearrangements, but also of targeted DNA hypomethylation. This hypomethylation of heterochromatic DNA sequences is seen in many cancers and may predispose to chromosome rearrangements in cancer as well as in ICF., (Copyright 2000 S. Karger AG, Basel.)

We describe three unrelated patients with adrenal insufficiency and RSH or Smith-Lemli-Opitz syndrome (SLOS), a disorder due to deficient synthesis of cholesterol. These patients presented with hyponatremia, hyperkalemia, and decreased aldosterone-to-renin ratio, which is a sensitive measure of the renin-aldosterone axis. All patients had profound serum total cholesterol deficiency (14-31 mg/dl) and marked elevation of 7-dehydrocholesterol (10-45 mg/ dl). Two patients were newborn infants with 46, XY karyotypes and complete failure to masculinize; one of these patients also had cortisol deficiency. Both patients died within 10 days of birth of cardiopulmonary complications while on adrenal replacement therapy. The third patient diagnosed with SLOS at birth presented at age 7months with fever and diarrhea and was noted to have profound hyponatremia. This patient is maintaining normal serum electrolytes on mineralocorticoid replacement. We conclude that adrenal insufficiency may be a previously undetected and treatable manifestation in SLOS. We hypothesize that deficiency of cholesterol, an adrenal hormone precursor, may lead to insufficient synthesis of adrenal steroid hormones.

We report on two sibs with a paracentric inversion of chromosome 1 [inv(1)(p22.3p34.1)] and a small deletion of the same chromosome (p34.1-->p34.3). They presented with learning disabilities and disturbed conduct but lacked the more severe manifestations usually associated with autosomal chromosome deletion. Born to an alcoholic mother and later placed in foster care because of abuse and neglect, the behavior abnormalities they present are likely to be associated with their traumatic postnatal experience. Microscopic deletions without significant morphological phenotypic expression have been described but are rarely reported. Most reported cases of interstitial deletion of 1p had associated malformations and psychomotor retardation. These sibs may represent the first evidence that deletion of 1p34.1-->1p34.3 may have little impact on the phenotype.

We present a patient with developmental delay, minor anomalies, and duplication 18p confirmed by fluorescence in situ hybridization with whole chromosome 18 painting probe (Oncor p5218). Our observation confirms the findings of other investigators that duplication 18p is not associated with major malformations.

We report on a white man with Prader-Willi syndrome (PWS) and del(15)(q11.2q13), confirmed by fluorescence in situ hybridization (FISH), who had hyperlipidemia, insulin-dependent diabetes, and the early onset and rapid progression of diabetic retinopathy and nephropathy within 4 years after diagnosis of diabetes. The spectrum of glucose intolerance in patients with PWS is discussed, as well as those references which suggest that the prevalence of hyperlipoproteinemia in this condition may be greater than previously recognized. We suggest the need for clarification of both the prevalence and types of hyperlipoproteinemia, as well as the pathophysiology of glucose intolerance and correlation with molecular cytogenetic findings. We also encourage careful monitoring for diabetic complications to further clarify the prevalence and possible accelerated course of microvascular lesions.

Intrachromosomal rearrangements usually result from three of fewer breaks. We report a complex intrachromosomal rearrangement resulting from five breaks in one chromosome 10 of a phenotypically normal father of two developmentally delayed children. GTG-banding analysis of the father's rearranged chromosome 10 suggested in initial pericentric inversion followed by an insertion from the short arm into the terminal band of the long arm [der(10) (pter-->p13::q21.2-->p12.2::q22.1::-->q26.3::q22.1-->q 21.2::p12.2-->p13::q26.3-->qter)]. To our knowledge, this rearrangement is the most complex ever reported in a single chromosome. Both children inherited a recombinant chromosome 10 with loss of the insertion and the segment distal to it [rec(10)der(pter-->p13: :q21.2-->p12.2::q22.1-->q26.3:)]. Mechanisms for both rearrangements are proposed.

Dicentrics are among the most common structural abnormalities of the human Y chromosome. Predicting the phenotypic consequences of different duplications and deletions of dicentric Y chromosomes is usually complicated by varying degrees of mosaicism (45,X cell lines), which may, in some cases, remain undetected. Molecular studies in patients with dicentric Y chromosomes have been few, and only two studies have attempted to determine the presence of SRY (the putative testis-determining factor gene). We report an 18-year-old female with short stature, amenorrhea, hirsutism, hypoplastic labia minora, and clitoromegaly who has a 45,X/46,X,idic(Y)(p11.32)/47,X,idic(Y)(p11.32),idic(Y) (p11.32) karyotype. Southern analysis using Y-specific probes (Y97, 2D6, 1F5, pY3.4) and polymerase chain reaction (PCR) analysis using primers for ZFY and SRY were positive for all loci tested, indicating that almost all of the Y chromosome was present. Our findings and an extensive review of the literature emphasize the importance of molecular analyses of abnormal Y chromosomes before any general conclusions can be reached concerning the relative effects of the Y-chromosome abnormality and mosaicism on sexual differentiation.

We report the first observation of a chromosome abnormality in a patient with typical juvenile ceroid-lipofuscinosis (NCL), who was found to have an apparently balanced translocation between chromosomes 10 and 18 [t(10;18)(q22.1;q21.1)]. Since juvenile NCL was previously mapped to 16p12, this report raises the possibility of heterogeneity in this form of NCL.

We report on a 15-year-old black boy with severe mental retardation, multiple congenital anomalies, and a supernumerary ring chromosome mosaicism. Fluorescence in situ hybridization with a chromosome 1 painting probe (pBS1) identified the ring as derived from chromosome 1. The karyotype was 46,XY/47,XY,+r(1)(p13q23). A review showed 8 reports of ring chromosome 1. In 5 cases, the patients had a non-supernumerary ring chromosome 1 resulting in partial monosomies of the short and/or long arm of chromosome 1. In 3 cases, the presence of a supernumerary ring resulted in partial trisomy of different segments of chromosome 1. In one of these cases the supernumerary ring was composed primarily of the centromere and the heterochromatic region of chromosome 1, resulting in normal phenotype. Our patient represents the third report of a supernumerary ring chromosome 1 resulting in abnormal phenotype.

We report on a black male child with congenital hypoplasia of the adrenal gland (CHA) with a de novo duplication of 5p [dir dup(5) (p13.3-->p15.1)], confirmed by fluorescence in situ hybridization (FISH). In addition to a characteristic clinical course, the patient has hyperpigmentation (melanoderma) since birth, normal external genitalia, marked elevation of ACTH, and absent response to an IV ACTH challenge. To the best of our knowledge, this is the first case of congenital hypoplasia of the adrenal gland associated with a chromosome abnormality. Reviews of dup (5p) and of our patient suggest that duplication of 5p13.3-pter has only minor phenotypic effect, while duplication of the relatively small critical segment p11-p13.2 apparently causes far more deleterious changes. The concurrence of CHA and dup(5p) in our patient may indicate the possible gene localization of an autosomal form of CHA to either at or near 5p13.3 or 5p15.1.

We describe a method for rapid and efficient polymerase chain reaction (PCR) amplification of specific target DNA sequences directly from cells fixed in 3:1 methanol-acetic acid (Carnoy's fixative) for routine cytogenetic analysis. The fixed cells used had been stored at -20 degrees C from a few weeks up to 6 years. Primer sets used correspond to loci on an autosome (retinoblastoma, RB1), as well as the X (Duchenne muscular dystrophy, DMD) and Y (sex-determining region of the Y, SRY) chromosomes. Sizes of amplified products were the expected 400, 251 and 609 bps, respectively. No differences in quality of amplification products were found between PCR templates obtained from fresh tissues or from cells fixed for varying lengths of time in Carnoy's fixative. This technique has the following advantages: (1) it allows retrospective studies of genetic disorders from archived specimens; (2) it requires only a limited number of cells; (3) it is rapid and simple; and (4) it avoids multistep procedures required in extraction of the DNA.

Previously isolated human placental cDNA clones represent a fusion of specific RNA sequences encoded by two genes: lysosomal chitobiase (CTB) and G-protein gamma 5 subunit (GNG5, Fisher and Aronson, 1992a, 1992b). Both genes have now been mapped to 1p by PCR analysis of somatic cell hybrids and further refined to 1p22 by fluorescence in situ hybridization (FISH) using a YAC clone that contains both the chitobiase and gamma 5 genes.

Duplication within Xp21 causes female or intersexual development in human embryos with an XY chromosome complement. We have mapped the responsible gene, SRVX (sex reversal X), in XY-sex-reversed maternal half siblings who had inherited the duplication from their mother. The limited size of the duplication in our cases, relative to its extent in other similar cases, allows assignment of the SRVX locus to Xp21.2-->p22.11. We infer that SRVX is part of a pathway of sex-determining genes that includes SRY and SRA1, the latter recently assigned to chromosome 17q. If mutation of SRA1 or SRVX can reverse the sex of the XY fetus, this would explain why mutation within SRY is found only sporadically in women with XY gonadal dysgenesis.

We report on a boy with excessively wrinkled skin, mild micro/brachycephaly with mild hydrocephalus and slightly small temporal lobes, apparently low-set ears, retro/micrognathia and cleft soft palate (Pierre-Robin anomaly), patent ductus arteriosus and foramen ovale, pulmonary hypoplasia, eventration of the left hemidiaphragm, right cryptorchidism, a sacral dimple, flexion contractures of fingers and knees, and equinovarus deformities of both feet. The infant had a de novo dir dup(1)(pter-->q25::q12-->qter). Partial duplications involving proximal 1q have rarely been reported. Furthermore, this is the first case of proximal duplication of chromosome 1q with unequivocal identification using fluorescence in situ hybridization (FISH) with a chromosome 1 painting probe.

We report of case of a complex chromosomal rearrangement detected prenatally and studied with traditional banding methods and fluorescence in situ hybridization. The combination of these techniques showed that four chromosomes were involved in the translocation. Nine breakpoints were proposed to explain these results. Some of the findings could only be detected with fluorescence in situ hybridization, demonstrating the usefulness of this technique in characterizing chromosomal abnormalities that would otherwise be difficult to interpret correctly with classical cytogenetics alone.

An 11-year-old girl with short stature, mental retardation, and mild dysmorphic features was found to have an inverted duplication of most of the short arm of the X chromosome [dic inv dup(X)(qter-->p22.3::p22.3-->cen:)]. Her mother, who is also short and retarded, carries the same duplication. Fluorescence in situ hybridization with an X chromosome library, and with X centromere-specific alpha satellite and telomere probes, was useful in characterizing the duplication. In most females with structurally abnormal X chromosomes, the abnormal chromosome is inactivated. Although the duplicated X was consistently late replicating in the mother, X chromosome inactivation studies in the proband indicated that in 11% of her lymphocytes the duplicated X was active.

We describe a mother and daughter with typical cri du chat syndrome. Previous investigators have noted the lack of information about the reproductive fitness of patients with this disorder. This report demonstrates that females with cri du chat syndrome are fertile, can gestate and likewise deliver affected offspring, which has significant management and counseling implications.

Previous cytogenetic studies of patients with systemic sclerosis have obtained conflicting results regarding the presence of chromosomal anomalies. We studied 38 patients and 15 controls to determine whether these inconsistencies were due to differences in the subgroups of patients who were studied. Because many patients with systemic sclerosis produce autoantibodies to protein antigens that have been implicated in chromosome structure and function, we further hypothesized that the presence of these autoantibodies might correlate with the presence of chromosomal anomalies. Patients were classified into clinical subgroups based on the extent of their disease. Their sera were assayed for autoantibodies to topoisomerase I and centromere proteins (CENP-A, CENP-B, and CENP-C) by immunoblotting. Cytogenetic analyses for aneuploidy and chromosome breaks were performed. Anticentromere antibody positive (ACA+) patients had significantly more aneuploidy than either ACA negative (ACA-) patients or controls (P = 0.041). Although the patient group, when considered as a whole, had significantly greater aneuploidy than the control group (P < 0.005), patients who were ACA--did not have more aneuploidy than the controls had. Patients with Type I disease (sclerodactyly), the majority of whom were ACA+, also had significantly more aneuploidy than did either the controls or patients with Type III (diffuse) disease, most of whom were ACA- (P < 0.005). ACA+ patients also had more chromatid breaks than the controls had (P < 0.05). The correlation between the presence of ACAs and chromosomal aneuploidy suggests that aneuploidy may be the result of nondisjunction secondary to centromeric dysfunction. In support of this hypothesis, the ACA+ patients who had antibodies to CENP-C exhibited more chromosomal aneuploidy than did either anti-CENP-A or anti-CENP-B positive patients (P < 0.048). Unlike CENP-A and CENP-B, which are present at both functional and inactivated centromeres, CENP-C is present at the kinetochore of functional centromeres.

Ataxia-telangiectasia (A-T) is a syndrome that has an extremely high incidence of cancer. Patients with the disease are homozygous for a mutant gene, the A-T gene, located at 11q23. Of these individuals, 30-40% develop cancer. Of these cancers, 80% are lymphoid. Those heterozygous for the A-T gene also have an increased frequency of cancer, the most notable being the 6.8-fold increase of breast cancer in females carriers. The syndrome is characterized cytogenetically by increased nonrandom chromosome breaks and rearrangements in lymphocytes involving the sites of the immunoglobulin and T-cell receptor genes. Clones of cells having the same rearrangements are often present in the blood of the A-T patients and if the rearrangements involve certain sites, especially a locus within 14q32, the propensity to progress to a malignant transformation is great. Sequencing the A-T gene and ascertaining its function should contribute significantly to our understanding of the molecular mechanisms underlying cancer susceptibility.

Roberts syndrome is an inherited human condition that is of particular interest because separation of centromeres and constitutive heterochromatin is observed in metaphase chromosomes. In this study we investigated the frequency of other cytological abnormalities in three Roberts syndrome patients. Our findings when taken with previous cytological reports emphasize that there are other features that are equally characteristic of Roberts syndrome: (1) aneuploidy with random chromosome loss and (2) micronuclei and/or nuclear lobulations of 8%-24% of interphase cells. We observed abnormal chromosome movement involving one or all the chromosomes during anaphase. Evidence is presented suggesting that aneuploidy, micronuclei and abnormal nuclear morphology are a direct result of lagging chromosomes. The cytological features documented for Roberts syndrome indicate that this is a human mitotic mutant.

We have used molecular and cytogenetic methods to study the derivation of a ring chromosome 13 in the fetus of a woman mosaic for a translocation chromosome 13. DNA analysis showed that the translocation chromosome was a Robertsonian translocation, not an isochromosome. We suggest that the ring is derived from the translocation chromosome by breaks in both long arms and subsequent reunion, r(13) (q12q14).

The average sphingomyelinase activity of fibroblasts obtained from 12 Niemann-Pick type C patients was 37.9% of that of normal fibroblasts (27.2 versus 72 nmol (mg protein)-1 h-1) when the cells were cultured in minimum essential medium containing 13% fetal bovine serum. Following replacement of the above medium with medium in which the lipoprotein fraction had been removed from the fetal bovine serum, the sphingomyelinase activity rose over a 7-day period from about 1/3 of normal to normal or above. Upon reintroduction of medium containing 10% fetal bovine serum which had not been extracted, the sphingomyelinase activity of the Niemann-Pick type C cells again fell within 48 h to 30% of the normal controls. In contrast, cell lines from patients with either Niemann-Pick Type A or B were not influenced by the presence or the absence of lipoprotein, i.e. lacked sphingomyelinase activity under all culture conditions examined. Histochemical staining with filipin showed an inverse relationship between the sphingomyelinase activity and intracellular, free, unesterified, cholesterol level. Moreover, immunochemical staining with an antibody against a lysosomal membrane protein provided direct evidence that the accumulation of unesterified cholesterol in cells cultured in regular (non-extracted) medium occurred within lysosomes and/or related organelles.

We studied a family in which congenital cataracts were found in a father and son who had a reciprocal translocation between the short arms of chromosomes 3 and 4 [t(3;4)(p26.2;p15)]. The father's parents and brother had normal chromosomes and no evidence of cataracts. While results of these studies do not prove a causal relationship, they do strongly suggest that the areas near the break points involved in the translocation (3p26.2 and 4p15) would be good sites for further investigations into the genetic basis of this type of cataract.

Chromosomes of white blood cells from 10 girls with the Rett syndrome, 9 of their mothers and 17 unrelated controls (5 girls and 12 women) were examined for the presence of the fragile site on Xp22 under different culture conditions. Six of the 10 Rett patients were fra(X)(p22) positive while 4 failed to express this fragile site. In the 6 patients expressing the fragile site it was present in 1 to 3% of all cells. Similarly, 5 of the mothers and 6 of the control women showed this fragile site, with a frequency of 1 to 9%. Concordance analysis showed that in the 9 mother-daughter pairs examined, 5 had concordant results while 4 of the pairs were discordant. These findings are very similar to those found in non-Rett individuals by ourselves and other investigators. These data agree with published findings that fra(X)(p22) is a common fragile site in normal individuals. Therefore, we conclude that the incidence of the Xp22 fragile site in the Rett syndrome does not differ from that found in various non-Rett individuals, including normal persons. This indicates to us that fra(X)(p22) cannot serve as a chromosomal marker for the Rett syndrome.

A newborn male with a large diaphragmatic hernia presented in severe respiratory distress. Additional features included a paucity of subcutaneous tissue, mild facial dysmorphism, webbing of the neck, genital hypoplasia, and flexion contractures of the fingers. His karyotype showed a previously unreported de novo interstitial deletion of the long arm of chromosome 1 [46,XY,del(1)(pter----q32.3::q42.3----qter)]. Regional mapping of five human genes that have been provisionally assigned to chromosome 1 was performed by restriction analysis of genomic DNA from this patient. Glucocerebrosidase, H4 histone, renin, and alpha-spectrin genes mapped outside the deleted region, whereas an H subunit of the ferritin gene mapped to 1q32----q42. These results indicate the utility of chromosomal deletions in gene mapping, and the importance of karyotype analysis in newborns with diaphragmatic hernias.

Associations between nucleolus organizer regions (NORs) and non-acrocentric chromosomes were scored in 2,800 metaphase spreads from PHA-stimulated lymphocyte cultures (48 h) from 14 individuals. The preparations were both silver stained and C-banded. In order to calculate the expected values for associations, the ratio of heterochromatin length to euchromatin length was established for each subject. Individual C-band lengths and centromeric lengths were also determined. When silver connective (SC) associations with heterochromatin were compared to SC associations with euchromatin, the number of associations with heterochromatin was significantly greater than expected (P less than 0.000001) for each subject. The SC associations were not distributed randomly over the heterochromatin of the non-acrocentrics. Chromosomes 1 and 2 had significantly more than expected. Chromosomes 17, 18, 19, 20, and the Y had fewer than expected. NOR associations with euchromatic segments also showed a nonrandom pattern of distribution.

A reliable technique for combined C-banding and silver staining of metaphase chromosomes which uses trypsinization is described. Slides are first immersed in dilute HCl to remove residual cytoplasm from around the chromosomes. They are then treated with saturated barium hydroxide and incubated overnight in saline sodium citrate (0.30 M NaCl, 0.03 M sodium citrate, adjusted to pH 7.0 with HCl). Following the C-banding pretreatment, a two-step method of silver staining which employs a protective colloidal developer is used to stain the nucleolar organizer regions (NORs) of the chromosomes. Silver staining is followed by trypsinization to remove extraneous silver precipitate from the chromosome arms which permits the C-bands to be stained with Giemsa. The method works equally well with fresh and aged mitotic chromosome preparations and gives consistent staining of both heterochromatin and active NORs in metaphases across the slide.