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Studies examining altered imprinted gene expression in cancer compare the observed expression pattern to the normal expression pattern for a given tissue of origin, usually the somatic expression pattern for the imprinted gene. Germ cell tumors (GCTs), however, require a developmental stage-dependent comparison. To explore using methylation as an indicator of germ cell development, we determined the pattern of methylation at the 5' untranslated region of SNRPN in 89 GCTs from both children and adults. Fifty-one of 84 tumors (60.7%) (12/30 (40%) of cultured pediatric GCTs, 23/36 (63.9%) of frozen adult GCTs, and 16/23 (69.5%) of frozen pediatric GCTs, with five samples having results from both cultured and uncultured material) demonstrated a nonsomatic methylation pattern after dual digestion with XbaI, NotI, and Southern blot analysis. In contrast, only 2 of 18 (11%) control samples (16 non-GCTs and 2 normal ovaries) exhibited a nonsomatic pattern. In both cases, the result was shown to be due to copy number differences between maternal and paternal homologs, unlike the GCTs in which there was no evidence of an uneven homolog number. A comparison of the data for only the gonadal GCTs and the control data showed a highly significant difference in the proportion of tumors with methylation alterations at this locus (P = 0.0000539). Since there is no published evidence of the involvement of SNRPN methylation changes in the development of malignancy, the data suggest that the methylation pattern of SNRPN in GCTs reflects that of the primordial germ cell giving rise to the tumor., (Copyright 2001 Wiley-Liss, Inc.)

The trace amine para-tyramine is structurally and functionally related to the amphetamines and the biogenic amine neurotransmitters. It is currently thought that the biological activities elicited by trace amines such as p-tyramine and the psychostimulant amphetamines are manifestations of their ability to inhibit the clearance of extracellular transmitter and/or stimulate the efflux of transmitter from intracellular stores. Here we report the discovery and pharmacological characterization of a rat G protein-coupled receptor that stimulates the production of cAMP when exposed to the trace amines p-tyramine, beta-phenethylamine, tryptamine, and octopamine. An extensive pharmacological survey revealed that psychostimulant and hallucinogenic amphetamines, numerous ergoline derivatives, adrenergic ligands, and 3-methylated metabolites of the catecholamine neurotransmitters are also good agonists at the rat trace amine receptor 1 (rTAR1). These results suggest that the trace amines and catecholamine metabolites may serve as the endogenous ligands of a novel intercellular signaling system found widely throughout the vertebrate brain and periphery. Furthermore, the discovery that amphetamines, including 3,4-methylenedioxymethamphetamine (MDMA; "ecstasy"), are potent rTAR1 agonists suggests that the effects of these widely used drugs may be mediated in part by this receptor as well as their previously characterized targets, the neurotransmitter transporter proteins.

Interstitial duplications of chromosomes 1p are rare, with only 14 cases previously reported in the literature, and those have not revealed a unique syndrome. The phenotypes include multiple congenital abnormalities and both intra- and extra-uterine growth retardation. In general, the patients do poorly and do not survive beyond the age of several months. We report a newborn male with karyotype 46, XY, inv dup(1)(qter--> p34.3::p34.3-->p32.3::34.3-->pter) with multiple congenital abnormalities including congenital heart disease and co-existing portal and pulmonary hypertension. The chromosome 1 origin of the extra material was confirmed with fluorescent in situ hybridization (FISH). Review of the GDB [Human Genome Database, 1990] reveals that the duplicated region includes the locus EDN2 that encodes endothelin-1, a potent vasoconstrictor, making genetic overdosage of this protein a likely etiology of the pulmonary hypertension. The diffuse abnormalities show effects in multiple cell lines and suggest that this region of chromosome 1p could be involved in determining cell migration and/or differentiation during organogenesis., (Copyright 2001 Wiley-Liss, Inc.)

The prenatal diagnosis of trisomy 20 mosaicism presents a challenge for practitioners and parents. The diagnosis implies an uncertain risk for an inconsistent set of physical and developmental findings, as well as a substantial chance for a child that is normal physically and developmentally. We report two girls (ages nine years one month and eight years one month) with normal intelligence and hypopigmented skin areas. Both girls were born after a prenatal diagnosis of trisomy 20 mosaicism in amniocytes. Case 1 had 83% and 57% trisomy 20 cells from two separate amniocenteses and Case 2 had 90% trisomy 20 cells from an amniocentesis. Trisomy 20 was confirmed after birth in urinary sediment (25%) and chorionic villus cells (15%) in Case 1, while cord blood lymphocytes (30 cells) and skin fibroblasts (50 cells) had only 46,XX cells. Trisomy 20 was confirmed after birth in urinary sediment (100%), placenta (100%), cord (10%), amniotic membrane (50%), and skin fibroblasts (30%) in Case 2, while cord blood lymphocytes (100 cells) had only 46,XX cells. This is the first report of a hypopigmented pigmentary dysplasia associated with isolated trisomy 20 mosaicism. Our patients are the oldest reported children with trisomy 20 mosaicism confirmed after birth., (Copyright 2001 Wiley-Liss. Inc.)

The chromosomes of 81 pediatric germ cell tumors (GCTs) were analyzed as part of two clinical treatment trials, INT-0098 and INT-0097, conducted by the Children's Cancer Group. The analysis of chromosome results showed differences with respect to sex, age, tumor location, and histology. Sixteen of 17 benign teratomas of infants and children less than 4 years old and from gonadal and extragonadal locations were chromosomally normal. Twenty-three malignant GCTs from gonadal and extragonadal locations of the same age group were endodermal sinus tumors and varied in their karyotypic findings. The most common abnormalities were gains of 1q and chromosome 3. Of eight benign ovarian teratomas from older girls, five with normal G-banded karyotypes were determined to be homozygous for Q-band heteromorphisms, suggesting a meiosis II error. Among the 12 malignant ovarian GCTs from older girls, the common abnormalities were loss of 1p/gain of 1q, +3, +8, +14, and +21. Four of eight extragonadal tumors from older boys demonstrated +21; one had +X. Five of the eight had associated constitutional chromosome abnormalities, including one trisomy 21 and three with Klinefelter syndrome. The testicular GCTs of adolescents had abnormalities resembling those found in adult testicular GCT, including near-triploidy, loss of chromosomes 11, 13, and 18, and gain of chromosomes 7, 8, the X chromosome, and an isochromosome 12p. The gain of an isochromosome 12p was only frequent in the tumors from adolescent boys. Deletion of 1p/gain of 1q and +3 were the most common abnormalities among the malignant tumors from both sexes.

We present clinical outcome, through several years of follow-up, of 4 mentally retarded patients, each with a small interstitial deletion in the long arm of chromosome 2, within a region on which clinical reports are infrequent. Our patient 1 was found to have del(2)(q22.3q23.3); patients 2 and 3, del(2)(q23.3q24.2); and patient 4, del(2) (q24.2q31). By comparison of our cases with each other and with those previously published with comparable interstitial deletion, we attempted to identify characteristic clinical findings. Short neck with excessive cervical skin was seen with monosomy of chromosome 2 bands q22.3-q23.3, while hypertrichosis and a peculiar high pitched cry were seen with monosomy of chromosome 2 bands q23.3-q24.2. As suggested by Moller et al. [1984: Hum Genet 68:77-86], a cleft between the first and second toes was seen with monosomy of chromosome 2 bands q24.2-q31. In addition, seizure disorder was present in patients 1 and 4 (with the more proximal and distal deletions, respectively).

Cells from individuals with Fanconi anemia (FA) arrest excessively in the G2/M cell cycle compartment after exposure to low doses of DNA cross-linking agents. The relationship of this abnormality to the fundamental genetic defect in such cells is unknown, but many investigators have speculated that the various FA genes directly regulate cell cycle checkpoints. We tested the hypothesis that the protein encoded by the FA group C complementing gene (FAC) functions to control a cell cycle checkpoint and that cells from group C patients (FA[C]) have abnormalities of cell cycle regulation directly related to the genetic mutation. We found that retroviral transduction of FA(C) lymphoblasts with wild-type FAC cDNA resulted in normalization of the cell cycle response to low-dose mitomycin C (MMC). However, when DNA damage was quantified in terms of cytogenetic damage or cellular cytotoxicity, we found similar degrees of G2/M arrest in response to equitoxic amounts of MMC in FA(C) cells as well as in normal lymphoblasts. Similar results were obtained using isogenic pairs of uncorrected, FAC- or mock-corrected (neo only) FA(C) cell lines. To test the function of other checkpoints we examined the effects of hydroxyurea (HU) and ionizing radiation on cell cycle kinetics of FA(C) and normal lymphoblasts as well as with isogenic pairs of uncorrected, FAC-corrected, or mock-corrected FA(C) cell lines. In all cases the cell cycle response of FA(C) and normal lymphoblasts to these two agents were identical. Based on these studies we conclude that the aberrant G2/M arrest that typifies the response of FA(C) cells to low doses of cross-linking agents does not represent an abnormal cell cycle response but instead represents a normal cellular response to the excessive DNA damage that results in FA(C) cells following exposure to low doses of cross-linking agents.

Smith-Magenis syndrome (SMS) comprises a complex physical and behavioral phenotype that is associated with an interstitial deletion of chromosome 17p11.2. The deletions observed in patients can range from <2 to >9 megabases of DNA and may include more than 100 genes. In order to determine the critical deletion interval responsible for the syndrome phenotype, we have examined several patients with varying deletions involving 17p11.2 by somatic cell hybrid analyses. We have binned 112 markers along 17p11.2, including 27 markers within the critical interval for SMS, which is bound proximally by D17S29 and distally by cCI17-638. In addition, we present two patients who carry deletions involving 17p11.2 but do not exhibit the typical features of SMS. Patients such as these will allow genotype:phenotype correlations to be made and the gene(s) responsible for the SMS phenotype to be determined.

Recently we reported on three unrelated children with neural tube defects (NTDs) and deletion of 22q11. Two of these children have velo-cardio-facial syndrome and the third DiGeorge sequence. Thus, NTDs appear to be part of the clinical picture due to 22q11 deletion. To further explore this association and to clarify what findings should prompt testing for this deletion in individuals with NTDs, we have reviewed all patients in a large regional spina bifida clinic population. Two hundred ninety-five patients with NTDs were identified by chart review. Charts were reviewed for congenital heart defect, minor facial anomalies, thymic hypoplasia, cleft lip and/or palate, hypocalcemia, and a family history of a NTD, congenital heart defect, or cleft lip and/or palate. A total of 22 patients was identified with NTD and at least one more clinical trait and/or a positive family history. Sixteen children received cytogenetic and molecular testing including the three previously reported patients diagnosed with a 22q11 deletion. Results of cytogenetic and molecular studies of the remaining 13 patients were normal. Deletion of 22q11 is an infrequent cause of NTDs. We recommend testing for the 22q11 deletion in patients with a NTD and conotruncal heart defect. Testing should be considered in patients with a NTD who have a first degree relative with a conotruncal heart defect or have additional clinical findings of VCFS or DGS.

Autosomal dominant Charcot-Marie-Tooth type-1A neuropathy (CMT1A) is a demyelinating peripheral nerve disorder that is commonly associated with a submicroscopic tandem DNA duplication of a 1.5-Mb region of 17p11.2p12 that contains the peripheral myelin gene PMP22. Clinical features of CMT1A include progressive distal muscle atrophy and weakness, foot and hand deformities, gait abnormalities, absent reflexes, and the completely penetrant electrophysiologic phenotype of symmetric reductions in motor nerve conduction velocities (NCVs). Molecular and fluorescense in situ hybridization (FISH) analyses were performed to determine the duplication status of the PMP22 gene in four patients with rare cytogenetic duplications of 17p. Neuropathologic features of CMT1A were seen in two of these four patients, in addition to the complex phenotype asociated with 17p partial trisomy. Our findings show that the CMT1A phenotype of reduced NCV is specifically associated with PMP22 gene duplications, thus providing further support for the PMP22 gene dosage mechanism for CMT1A.

Prader-Willi syndrome (PWS) is most often the result of a deletion of bands q11.2-q13 of the paternally derived chromosome 15, but it also occurs either because of maternal uniparental disomy (UPD) of this region or, rarely, from a methylation imprinting defect. A significant number of cases are due to structural rearrangements of the pericentromeric region of chromosome 15. We report two cases of PWS with UPD in which there was a meiosis I nondisjunction error involving an altered chromosome 15 produced by both a translocation event between the heteromorphic satellite regions of chromosomes 14 and 15 and recombination. In both cases, high-resolution banding of the long arm was normal, and FISH of probes D15S11, SNRPN, D15S10, and GABRB3 indicated no loss of this material. Chromosome heteromorphism analysis showed that each patient had maternal heterodisomy of the chromosome 15 short arm, whereas PCR of microsatellites demonstrated allele-specific maternal isodisomy and heterodisomy of the long arm. SNRPN gene methylation analysis revealed only a maternal imprint in both patients. We suggest that the chromosome structural rearrangements, combined with recombination in these patients, disrupted normal segregation of an imprinted region, resulting in uniparental disomy and PWS.

Interstitial deletions of chromosome 4 have been described rarely and have had variable presentations. We describe the phenotypic characteristics associated with interstitial deletion of the p14-16 region of chromosome 4 in 7 patients with multiple minor anomalies in common, and with mental retardation. A review of published cases of interstitial deletions of the short arm of chromosome 4 is provided. These deletions present a distinct phenotype which is different from that of Wolf-Hirschhorn syndrome.

The clinicopathological features and the prognostic significance of acute myeloid leukaemia (AML) with trisomy 11 are currently unknown. In this study we describe 15 adult AML cases with trisomy 11. Trisomy 11 was the sole chromosomal anomaly in eight cases; the remaining seven cases were characterized by +11 in association with other karyotypic aberrations. Patients ages ranged from 34 to 79 years. 12 patients were male; three were female. Although there was no correlation of trisomy 11 with any specific FAB subgroup [M2 (n = 7), M1 (n = 5), M4/5 (n = 2), M3 (n = 1)] less mature forms predominated. Immunologically, the leukaemic blasts showed a strikingly consistent stem cell phenotype with expression of HLA-DR, CD34 and the myeloid antigens (CD15, CD33 and/or CD13). In addition, two cases expressed the B-cell associated antigen CD19. The presence of trilineage dysplasia, suggesting the presence of an underlying myelodysplasia (MDS), was observed at presentation in five cases; in another case MDS was evident at relapse only. Unexpectedly, MLL gene rearrangements were observed in two of four cases characterized by trisomy 11 as the sole karyotypic abnormality; however, MLL aberrations were not identified in three cases with trisomy 11 accompanied by other karyotypic anomalies. The majority of patients in each subgroup (i.e. those with and without additional cytogenetic abnormalities) achieved a short first complete remission (CR) (mean 8 months) and failed to obtain a second CR. Only one patient in each trisomy 11 subgroup is in a continuous CR for > 34 months. These findings suggest that trisomy 11 leukaemia is characterized by a stem/progenitor cell immunophenotype with poor response to standard chemotherapeutic regimens and an unfavourable prognosis.

Fragile X syndrome is the most common form of inherited mental retardation and results from the transcriptional inactivation of the FMR1 gene. In the vast majority of cases, this is caused by the expansion of an unstable CGG repeat in the first exon of the FMR1 gene. We describe here a phenotypically atypical case of fragile X syndrome, caused by a deletion that includes the entire FMR1 gene and > or = 9.0 Mb of flanking DNA. The proband, RK, was a 6-year-old mentally retarded male with obesity and anal atresia. A diagnosis of fragile X syndrome was established by the failure of RK's DNA to hybridize to a 558-bp PstI-XhoI fragment (pfxa3) specific for the 5'-end of the FMR1 gene. The analysis of flanking markers in the interval from Xq26.3-q28 indicated a deletion extending from between 160-500 kb distal and 9.0 Mb proximal to the FMR1 gene. High-resolution chromosome banding confirmed a deletion with breakpoints in Xq26.3 and Xq27.3. This deletion was maternally transmitted and arose as a new mutation on the grandpaternal X chromosome. The maternal transmission of the deletion was confirmed by FISH using a 34-kb cosmid (c31.4) containing most of the FMR1 gene. These results indicated that RK carried a deletion of the FMR1 region with the most proximal breakpoint described to date. This patient's unusual clinical presentation may indicate the presence of genes located in the deleted interval proximal to the FMR1 locus that are able to modify the fragile X syndrome phenotype.