The human 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD) gene cluster on chromosome 1p13 contains a presumptive pseudogene; 3 beta-HSD and CYP17 do not segregate with dominantly inherited hirsutism

Four hirsute females from a family exhibiting idiopathic dominant hirsutism were examined. Basal blood levels of delta 5 and delta 4 steroids were within the normal range, but ACTH stimulation led to increases in 17-hydroxypregnenolone and dehydroepiandrosterone that were significantly above control levels. Using polymorphic genetic markers, the genes for cytochrome P450c1717 encoded by CYP17, and the type I and II forms of 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD) were found not to segregate with hirsutism in this family, though a base substitution was detected in the 3' end of exon 1 of the gene for 3 beta-HSD type I in three of the four patients investigated. Analysis of PCR patients amplification products by denaturing gradient gel electrophoresis (DGGE) and sequencing revealed a novel homologue of exon 3 of 3 beta-HSD. DNA of one of the affected patients was used to create a genomic library in lambda gem 11 and clones containing the novel homologue were obtained and partially sequenced. The equivalent clone was obtained from a genomic library of an unrelated normal individual. The sequences of the clones from patient and control were identical and homologous to exons 2-4 of human 3 beta-HSD types I and II. No difference was found in the PCR primer sites that flanked the exons 3 homologue which led to its detection on DGGE gels. In both clones, stop codons and deletions were identified in the exon 4 homologue, leading to the deduction that the sequence comes from a pseudogene, which we call 3 beta-HSD psi 1. The pseudogene mapped to chromosome 1p13. It was concluded that dominantly inherited idiopathic hirsutism in this rare kindred was not due to deficiencies in 3 beta-HSD types I, II, or psi or of CYP17).

Diagnosis of ameloblastoma of the maxilla by fine needle aspiration. A case report

Ameloblastoma is a tumor of odontogenic epithelium that occurs in the jaws. We describe a case of an ameloblastoma of the maxilla that was diagnosed by fine needle aspiration cytology. The patient presented with a mass in the left maxillary sinus. Cytologic examination of the aspirate material showed numerous sheets of tightly packed basaloid cells. Several sheets of cells were surrounded by a row of columnar cells, with the nuclei oriented away from the basement membrane (peripheral palisading). Histologic examination of the resection specimen confirmed the presence of an ameloblastoma of the maxilla.

New members of the 3 beta-hydroxysteroid dehydrogenase gene family

Several bands of hydridization are detected when southern blots of human genomic DNA are proved with cDNA of 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD) type I. Two experimental approaches were adopted to estimate the size of the 3 beta-HSD gene family. Firstly, primer designed to amplify 3 beta-HSD type I and II genes were found on occasion to amplify DNA products of appropriate length but which were resolved as distinct sequences by denaturing gradient gel electrophoresis (DGGE). Five of these novel bands were cloned and their sequences were found to be closely related to 3 beta-HSD types I and II. Secondly, 57 genomic clones were selected from two lambda genomic libraries by hybridization with exonic probes of 3 beta -HSD type I. These were screened for novel members of the gene family by pcr amplification using various combinations of PCR primers to the type I and II genes, particularly those primers that previously amplified novel PCR products from genomic DNA. Amplification products from (lambda) clones were screened for novel sequences by DGGE. As a result of these approaches, at least five new members of the 3 beta-HSD gene family were found, one of which locates to the 3 beta -HSD type I and II gene cluster on 1p13. The existence of additional closely related but distinct members of the gene family should be recognized as a potential complication when screening PCR fragments for mutations in the type I and II genes. DGGE was found to be an exceedingly rapid means of screening amplification products from (lambda) clones to search for novel members of the gene family.

Familial split hand/split foot long bone deficiency does not segregate with markers linked to the SHFD1 locus in 7q21.3-q22.1

Ectrodactyly (split hand/split foot, SHSF) is characterized by the absence of middle rays of the hand or the foot. Cytogenetic analyses of some of the cases have indicated an association between chromosomal rearrangements involving 7q21.3-q22 and ectrodactyly. Based on these observations, an autosomal dominant form of ectrodactyly is assumed to reside in this region and the locus has been designated SHFD1 (split hand/split foot disorder). Here we report a large family where split hand/split foot long bone deficiency (SHFLD) segregates in an autosomal dominant mode. Linkage analysis, using microsatellite markers located in 7q21-q22, excludes this region from containing the gene responsible for SHFLD in this family. These results would appear to indicate genetic heterogeneity exists in autosomal dominant SHSF.

Comparison of biphasic and monophasic waveforms in epicardial atrial defibrillation

OBJECTIVES

Because biphasic waveforms have previously been shown to be more efficient than monophasic waveforms in defibrillation of the ventricle, we compared the efficiency of the two waveforms in defibrillation of the atria.

BACKGROUND

The development of an implantable atrial defibrillator would offer significant advantages over current approaches to the management of atrial fibrillation. Patient tolerance of atrial shocks from such a device, however, would depend critically on the deployment of an efficient waveform.

METHODS

Both the monophasic and biphasic shocks were of 8-ms duration, and the biphasic was a dual-capacitor waveform with equal first- and second-phase duration and leading-edge voltage. One hundred randomized atrial shocks were evaluated in 21 patients during cardiopulmonary bypass. Atrial fibrillation was induced by the application of alternating current. Atrial shocks were delivered through customized, contoured epicardial paddles applied to the posterior left atrial wall (surface area 11 cm2) and to the anterior right atrial wall (surface area 26 cm2).

RESULTS

For the monophasic waveform the delivered energy (joules) associated with 50% success (E50) was 1.44 J (95% confidence interval [CI] 0 to 11.2) and with 80% (E80) success 3.9 J (95% CI 2.42 to 109.8); for the biphasic waveform 50% success was achieved with 0.37 J (95% CI 0.36 to 0.38) (p = NS) and 80% success with 0.57 J (95% CI 0.56 to 0.58) (p < 0.05).

CONCLUSIONS

A biphasic waveform is more efficient than a monophasic waveform in atrial defibrillation. This may have implications for the development of an implantable atrial defibrillator for paroxysmal atrial fibrillation in addition to improvement of elective transthoracic and endocardial cardioversion of chronic atrial fibrillation.

Assignment of the gene encoding the human thyrotropin-releasing hormone receptor to 8q23 by fluorescence in situ hybridization

A cDNA for human thyrotropin-releasing hormone (TRH) receptor has been isolated from a human pituitary cDNA library. By using this cDNA as a biotinylated probe, the gene encoding the TRH receptor has been localized to chromosome 8q23 by in situ hybridization.

Agenesis of the corpus callosum associated with MASA syndrome

MASA syndrome includes mental retardation, adducted thumbs, shuffling gait and aphasia or speech delay. MASA syndrome, X-linked hydrocephalus and X-linked spastic paraplegia have been linked to the same markers on Xq28 and perhaps represent variation in the clinical expression of the same gene or manifestations of different mutant alleles. The present family includes five males in two generations with borderline to mild mental retardation (5/5), speech delay (5/5), spastic paraplegia (5/5), adducted thumbs (2/5) and marked hydrocephalus (1/5). Of these males, four were evaluated by MRI or CT scan and all four were determined to have partial to complete agenesis of the corpus callosum (ACC). DNA studies confirm linkage to Xq28 probe St14 (DXS52) with a lod score of 2.86 and no recombination. It is not known if X-linked ACC is linked to the same Xq28 region.

Regional chromosomal assignment of the Kell blood group locus (KEL) to chromosome 7q33-q35 by fluorescence in situ hybridization: evidence for the polypeptide nature of antigenic variation

The gene encoding the Kell blood group polypeptide has been localized to chromosome 7q33-35 by in situ hybridization using a biotinylated 1.1-kb DNA fragment containing the 3' half of the human cDNA. This assignment is in accord with genetic localization using antigenic variation as a marker, and strongly suggests that Kell antigenic determinants are part of the polypeptide chain rather than the associated sugar molecules.

Regional chromosomal assignment of the human platelet phosphofructokinase gene to 10p15

A cDNA for human platelet 6-phosphofructokinase (PFKP) has been isolated from a human Raji cell line cDNA library. Using this cDNA as a probe, the gene for human PFKP, previously mapped to chromosome 10pter-p11.1, has been further localized to 10p15 by non-isotopic in situ hybridization.

Duplication of distal 19q: clinical report and review

We report on a 20-month-old boy with duplication of the distal part of 19q. His karyotype is 46,XY, -22, + der(22),t(19;22)(q13.3;p11.2)mat. The propositus has multiple minor anomalies, congenital heart defects, seizures, profound psychomotor retardation, and growth impairment. These characteristics are similar to those in the other 10 reported cases of distal 19q duplication and help delineate the phenotype. A review of the literature is presented.

Chromosomal assignment of a large tRNA gene cluster (tRNA(Leu), tRNA(Gln), tRNA(Lys), tRNA(Arg), tRNA(Gly)) to 17p13.1

A cluster of tRNA genes (tRNA(UAGLeu), tRNA(CUGGln), tRNA(UUULys), tRNA(UCUArg)) and an adjacent tRNA(GCCGly) have been assigned to human chromosome 17p12-p13.1 by in situ hybridization using a 4.2 kb human DNA fragment for tRNA(Leu), tRNA(Gln), tRNA(Lys), tRNA(Arg), and, for tRNA(Gly), 1.3 kb and 0.58 kb human DNA fragments containing these genes as probes. This localization was confirmed and refined to 17p13.100-p13.105 using a somatic cell hybrid mapping panel. Preliminary experiments with the biotinylated tRNA Leu, Gln, Lys, Arg probe and metaphase spreads from other great apes suggest the presence of a hybridization site on the long arm of gorilla (Gorilla gorilla) chromosome 19 and the short arm of orangutan (Pongo pygmaeus) chromosome 19 providing further support for homology between HSA17, GGO19 and PPY19.

Analysis of the origin of Turner's syndrome using polymorphic DNA probes

Thirty-four families with a child or fetus with Turner's syndrome were studied using a series of polymorphic DNA probes. Analysis of the origin of the normal X chromosome was possible in all cases. In 16 families with 45,X (four fetuses and 12 livebirths), the observed X was maternal in each case, indicating a preferential loss of the paternal sex chromosome at, or before, conception. In the remaining 18 families with a variety of karyotypes, but especially in those where the child had an isochromosome of Xq or a ring X, there was again a strong tendency for the normal X to be maternal. Analysis of parental ages was performed with known origin of each abnormality, but no evidence for an increased or decreased parental age effect was detected.

Regional chromosomal assignment of the human mineralocorticoid receptor gene to 4q31.1

The gene for human mineralocorticoid receptor (hMR), previously mapped to chromosome 4, has been further localized to 4q31.1 by in situ hybridization using a biotinylated 3.75 kb human cDNA clone encoding the primary amino acid sequence of hMR as a probe. Preliminary comparative mapping studies in orangutan (Pongo pygmaeus) suggest localization of the probe to the long arm of chromosome 3.

Regional assignment of the human C1-inhibitor gene to 11q11-q13.1

In situ hybridisation using a biotinylated 1.8 kb human cDNA clone in both normal and structurally abnormal chromosomes supports regional localisation of the gene for human C1-inhibitor to chromosome 11q11-q13.1.

Genotype-phenotype correlations in XX males and their bearing on current theories of sex determination

Clinical, chromosomal and molecular studies of a group of 15 XX males confirm the presence of two main groups. A Y + ve group of ten patients exhibit sex reversal as the result of transfer of the distal end of the short arm of the Y chromosome, including testis determining factors, to the short arm of one X-chromosome, presumably by accidental crossing-over in paternal meiosis. The ten patients have Klinefelter's syndrome but differ from XXY cases in that they are short and shown no impairment of intelligence. The four Y-ve XX males have no demonstrable Y sequences and differ from Y + ve cases in abnormality of the external genitalia and invariable gynaecomastia; in this, they more closely resemble XX true hermaphrodites than XY males. These observations on Y - ve XX males and an additional exceptional Y + patients suggest that the ZFY locus is not essential for male differentiation and is not the primary testis determining factor. Male sex determination in sporadic, and familial Y-ve XX males and true hermaphrodites is likely to be the result of mutation in an X-linked TDF gene and its consequent escape from the constraints of X-inactivation. It seems premature to abandon the dosage model of sex determination on the recent evidence that ZFX does not show dosage compensation.

Regional chromosomal assignment of the human glucocorticoid receptor gene to 5q31

The gene for the human glucocorticoid receptor, previously mapped to chromosome 5, has been further localised to 5q31 by in situ hybridisation using a biotinylated 4.3-kb cDNA probe.

An aetiological study of isochromosome-X Turner's syndrome

In an attempt to resolve conflicting evidence from the literature concerning the existence of a paternal age effect in 46,X,i(Xq) Turner's syndrome, we have analysed data on all known cases ascertained in the main population centres of Scotland and on others ascertained in England, using population controls matched for year of birth. There was a significant (P = 0.02) increase of 2.3 years in the mean paternal age of the Scottish cases, and a smaller and non-significant increase in their mean maternal age. Logistic regression analysis confirmed that the primary association was with paternal, rather than maternal, age. For the English cases, however, there were small and non-significant decreases in their mean maternal and paternal ages. The differences between the two groups were also significant, but cannot be explained by any likely source of ascertainment bias. We therefore conclude that there is no evidence for a universal paternal age effect in this condition, but that at least one mechanism of origin, occurring with variable frequency, may be associated with increased paternal age. Using data from this and earlier published studies, we estimate the incidence of individuals with a 46,X,i(Xq) cell line to be between 3.3 and 13 per 10(5) female livebirths.

Recurrences of trisomy 18 and trisomy 13 after trisomy 21

Between 40 years and 43 years of age, a woman had three consecutive pregnancies with different prenatally diagnosed autosomal trisomies. This is compatible with the view that the predisposition to non-disjunction is not chromosome-specific.

Detection of a 15q deletion in a child with Angelman syndrome by cytogenetic analysis and flow cytometry

A proximal 15q deletion, del(15) (q11:q13), was detected in a child with Angelman syndrome by cytogenetic analysis of peripheral lymphocytes. The chromosomes of both parents appeared normal. Flow karyotype analysis carried out on lymphoblastoid cell lines derived from the child and her parents confirmed the presence of a de novo 15 deletion. The estimated size of the deleted segment ranged from 6.1-9.5% of chromosome 15 (approximately 6-9.3 million base pairs). The parental origin of the deleted chromosome could not be resolved by flow cytometry, but cytogenetic evidence suggested that it was derived from the smaller chromosome 15 homologue in the mother.

Interstitial deletion of the long arm of chromosome 2 with normal levels of isocitrate dehydrogenase

We report a 16 year old boy with the abnormal karyotype 46,XY,del(2)(q32.2q33.1) who has mental retardation, microcephaly, epilepsy, craniofacial dysmorphism, distinctive scalloped skin pigmentation, and normal levels of isocitrate dehydrogenase.

Isolation of chromosome-21-specific DNA probes and their use in the analysis of nondisjunction in Down syndrome

Thirteen single-copy, chromosome-21-specific DNA probes were isolated from a recombinant library made from flow-sorted chromosome 21 DNA and regionally mapped using a panel of somatic cell hybrids. Five probes mapped in the 21q21-q22.1 region, six to the 21q22.1-qter region, and one to each of the regions 21q22.1-q22.2 and 21q22.3. Two of these probes, one of which maps in the critical region for Down syndrome, have recently been shown to be expressed at high levels in Down syndrome brain tissue (Stefani et al. 1988). Following preliminary screening for restriction fragment length polymorphisms (RFLPs), five polymorphisms were discovered with four of the chromosome 21 DNA probes. A frequent MspI polymorphism detected by one of the probes was used in conjunction with four previously described polymorphic chromosome 21 probes to analyse the origin of nondisjunction in 33 families with a child or fetus with trisomy 21. The parental origin of the additional chromosome 21 was determined in 12 cases: in 9 (75%) of these it was derived from the mother and in the other 3 cases (25%) it was of paternal origin. Cytogenetic analysis of Q-banding heteromorphisms was informative in three of five families tested, and in each case the RFLP results were confirmed. The meiotic stage of nondisjunction was defined with confidence in five families, the results being obtained with pericentromeric RFLP or cytogenetic markers. Recombination between two nondisjoined chromosomes was demonstrated in one family and is consistent with the view that a lack of recombination between chromosome 21 homologues or failure of their conjunction is not the invariable cause of trisomy 21.