Distinct spectrum of CFTR gene mutations in congenital absence of vas deferens.

Congenital absence of the vas deferens (CAVD) is a frequent cause for obstructive azoospermia and accounts for 1%-2% of male infertility. A high incidence of mutations of the cystic fibrosis transmembrane conductance regulator (CFTR) gene has recently been reported in males with CAVD. We have investigated a cohort of 106 German patients with congenital bilateral or unilateral absence of the vas deferens for mutations in the coding region, flanking intron regions and promotor sequences of the CFTR gene. Of the CAVD patients, 75% carried CFTR mutations or disease-associated CFTR variants, such as the "5T" allele, on both chromosomes. The distribution of mutation genotypes clearly differed from that observed in cystic fibrosis. None of the CAVD patients was homozygous for delta F508 and none was compound heterozygous for delta F508 and a nonsense or frameshift mutation. Instead, homozygosity was found for a few mild missense or splicing mutations, and the majority of CAVD mutations were missense substitutions. Twenty-one German CAVD patients were compound heterozygous for delta F508 and R117H, which was the most frequent CAVD genotype in our study group. Haplotype analysis indicated a common origin for R117H in our population, whereas another frequent CAVD mutation, viz. the "5T allele" was a recurrent mutation on different intragenic haplotypes and multiple ethnic backgrounds. We identified a total of 46 different mutations and variants, of which 15 mutations have not previously been reported. Thirteen novel missense mutations and one unique amino-acid insertion may be confined to the CAVD phenotype. A few splice or missense variants, such as F508C or 1716 G-->A, are proposed here as possible candidate CAVD mutations with an apparently reduced penetrance. Clinical examination of patients with CFTR mutations on both chromosomes revealed elevated sweat chloride concentrations and discrete symptoms of respiratory disease in a subset of patients. Thus, our collaborative study shows that CAVD without renal malformation is a primary genital form of cystic fibrosis in the vast majority of German patients and links the particular expression of clinical symptoms in CAVD with a distinct subset of CFTR mutation genotypes.

Analysis of the CAG repeats in the SCA1 and B37 genes in schizophrenic and bipolar I disorder patients: tentative association between B37 and schizophrenia.

We have genotyped unrelated French Alsatian schizophrenic and bipolar I disorder (BPD) patients and matched controls for the polymorphic CAG repeats within the genes for spinocerebellar ataxia type 1 (SCA1) and dentatorubral-pallidoluysian atrophy (B37), in order to test their possible involvement in these disorders. No alleles with abnormally expanded repeats were found in either gene in patients and controls. Differences in allele and genotype frequencies for the SCA1 CAG repeat between patients and controls were not significant, thus providing no support for its role as a possible positional candidate gene for schizophrenia and BPD in our patients. Chi square testing revealed a significant result (P = 0.019) for an association between the B37 CAG repeat on chromosome 12p and schizophrenia. This result was more significant when only schizophrenics with a positive family history were compared with controls (P = 0.0001). The frequencies of alleles with 14, 12, and 15 CAG repeats differed the most, respectively, between schizophrenics and controls. When choosing the median of the B37 allele distribution (15 CAG repeats) as a threshold, there were significantly more controls than schizophrenics in the group with longer alleles (15 or more repeats) and more schizophrenics with shorter alleles (P = 0.002 by Fisher exact test). No particular genotype was associated with schizophrenia. This result possibly indicates linkage disequilibrium with another locus on chromosome 12p and therefore deserves further attention. No association was found between the B37 CAG repeat and patients with BPD.

Dopamine D3 receptor gene: organization, transcript variants, and polymorphism associated with schizophrenia.

DNA fragments from a genomic library were used to establish the partial structure of the human dopamine D3 receptor gene (DRD3). Its coding sequence contains 6 exons and stretches over 40,000 base pairs. The complete DRD3 transcript and three shorter variants, in which the second and/or third exon are deleted, were detected in similar proportions in brains from four controls and three psychiatric patients. The Msp I polymorphism was localized in the fifth intron of the gene, 40,000 base pairs downstream the Bal I polymorphism and a PCR-based method was developed for genotyping this polymorphism. The distribution of the Msp I and Bal I genotypes were not independent in 297 individuals (chi 2 = 10.5, df = 4, P = 0.03), but only a weak association was found between allele 1 of the Bal I polymorphism and allele 2 of the Msp I polymorphism (chi 2 = 3.99, df = 1, P = 0.04). The previously reported association between homozygosity at both alleles of the Bal I polymorphism and schizophrenia was presently maintained in an extended sample, comprising 119 DSM-III-R chronic schizophrenics and 85 controls (chi 2 = 5.3, df = 1, P = 0.02) and found more important in mal than in females. The presence of the Bal I allele 2 is associated with an early age at onset, particularly in males (df = 35, t value = 2.6, P = 0.014). In the same sample, allelic frequencies, genotype counts, and proportion of homozygotes for the Msp I polymorphism did not differ between schizophrenics and controls (chi 2 = 0.06, df = 1, P = 0.80, chi 2 = 0.22, df = 1, P = 0.90 and chi 2 = 0.16, df = 1, P = 0.69, respectively). The large distance of the Msp I polymorphism from the Bal I polymorphism and its localization in the 3' part of the gene may explain the discrepant results obtained with the two polymorphisms.

BalI and MspI polymorphisms of the dopamine D3 receptor gene in African Blacks and Caucasians.

An exonic BalI polymorphism and an intronic MspI polymorphism of the dopamine D3 gene were genotyped in 101 Caucasians from the Alsace and in 56 people from the Congo. This is the first study of the BalI polymorphism in sub-Saharan Africa and the first population study of the MspI site. BalI allele 1 was rare in the Congo (0.12) whereas it is the most frequent allele in all studies in Europe and Asia. MspI allele 1 was also significantly less frequent in the Congolese (0.24) than in Caucasians (0.52). D3 gene alleles show different frequencies in sub-Saharan Africa and may be useful for population studies.

Inverted and satellited Y chromosome in the orangutan (Pongo pygmaeus).

An inverted and satellited Y chromosome of almost acrocentric appearance was detected in seven of 14 male orangutans. In the remaining seven animals a submetacentric Y chromosome without NORs occurred. The high frequency with which the satellited Y chromosomes were associated with acrocentric autosomes and the positive AgNO3-staining of their satellite stalks clearly indicate the active state of the NOR on the Y chromosomes. DNA fingerprinting in two orangutan families showed that the inverted and satellited Y chromosomes in carrier orangutan males do not interfere with normal fertility. Within our sample of male orangutans studied, the inverted and satellited Y chromosome is restricted to Sumatran animals; all Bornean specimens possessed the submetacentric Y chromosome. The question arises whether these two kinds of Y chromosome differ constitutively between the Pongo pygmaeus subpopulations.

Association between schizophrenia and homozygosity at the dopamine D3 receptor gene.

Disturbances in dopamine neurotransmission have been postulated to underlie schizophrenia. We report data from two independent studies of a BalI polymorphism in the dopamine D3 receptor gene in patients with schizophrenia. In both studies, more patients than controls were homozygous (p = 0.005, p = 0.008). When pooled data were analysed, this difference was highly significant (p = 0.0001) with a relative risk of schizophrenia in homozygotes of 2.61 (95% confidence intervals 1.60-4.26).

Clinical reinvestigation and linkage analysis in the family with Episkopi blindness (Norrie disease).

We present the results of a clinical and genetic reinvestigation of the Cypriot family affected by an X chromosomally inherited eye disease originally published by Taylor et al, who coined the term Episkopi blindness. The pedigree was extended to 160 members, including 16 affected males out of 48 males at risk for the disease, most of whom were seen by one of us (PA). Affected males are blind with no associated symptoms and apparently are not mentally retarded. Thirty-nine family members agreed to blood sampling for genetic investigations. RFLP analysis was performed using probes from the region known to be deleted in some Norrie patients and polymorphic markers (DXS77, DXS7, MAOA, DXS255) from the proximal short arm of the X chromosome. There was no deletion for any of the probes in the affected males. Linkage analysis yielded positive lod scores for all informative markers (Z (DXS255, theta = 0) = 6.54, Z (MAOA, theta = 0) = 2.23, Z (DXS7, theta = 0) = 2.13). Thus, the conclusion that Episkopi blindness and Norrie disease (NDP, MIM *310600) are the same entity based on clinical evidence is now reinforced by gene mapping.

[Prenatal virus infections and orofacial clefts]. / Prenatálne vírusové infekcie a orofaciálne rázstepy.

A potential teratogenic activity of virus infections caused by the viruses of rubella, influenza, parotitis, hepatitis B, cytomegalovirus and the Epstein-Barr virus was investigated. Specific antibodies against these viruses were examined serologically in children with orofacial clefts and in their mothers and the results were compared with those obtained in control children and their mothers. Different micromethods were used in performing the examinations (ELISA, RIA, NIR, KFR, HIT). Evaluation of the results and their statistical processing supports the assumption that prenatal infection may have occurred in the series studied induced by the viruses of influenza, rubella, cytomegalovirus, and possibly also by the Epstein-Barr virus. No association with the viruses of parotitis and hepatitis B was established. (Tab. 5, Ref. 36.)

[Genetic counseling in prenatal diagnosis of cystic fibrosis]. / Genetische Beratung vor pränataler Diagnostik bei zystischer Fibrose.

In this paper we discuss the possible results of post- and prenatal DNA-diagnosis in cystic fibrosis with respect to the modification of the risk of having an affected child, depending on how closely the affected patient is related to those seeking advice. For parents with an affected child post- and prenatal DNA-diagnosis yields very reliable results and is an important factor in their decision process. In contrast to this, DNA-diagnosis for other relatives or individuals without an affected family member can lead to results which may intensify conflicts of decision making. This stresses the growing importance of genetic counseling before and after genetic diagnostic measures for cystic fibrosis.

Aldosterone deficiency II (CMO II deficiency) is not the result of a mutation of an MspI restriction site within the CYP11B gene.

We report our investigations of a German family with aldosterone deficiency (CMO II deficiency). Restriction fragment length polymorphism analysis using a P450c11 probe demonstrates that a MspI restriction site mutation within the CYP11B gene cannot be the underlying cause for this defect, as has been suggested previously.

New mutation versus exclusion at the alpha-1-antitrypsin locus: a multifaceted approach in a problematical paternity case.

In a case of disputed paternity with overwhelming indications of fatherhood for the putative father, as supported by serological tests and biostatistical evaluation, a classical exclusion constellation was found at the alpha 1-antitrypsin (PI) locus: mother PI M1; child PI M1M3, and putative father PI M1M2. Additional studies included PI oligonucleotide phenotyping and DNA fingerprint analysis. Results from the entire data set led us to assume a rare genetic event at the paternal PI locus. Intracistronal crossing-over offered the most parsimonious explanation, and was compatible with the PI gene DNA sequence and the amino acid sequences of the molecule and its allelic forms, as well as with the experimental findings.

Serological H-Y antigen and gonadal status in XYDOM sex-reversed mice.

Y chromosomes of feral mice (Mus musculus domesticus) from various localities, when introduced into the C57BL/6 laboratory strain, give rise to phenotypic females and true hermaphrodites both with the sex chromosome constellation XY. Sex-reversed animals of each type were examined macroscopically or histologically for gonadal status and H-Y antigenic activity by serological assay methods. Most XY females with histologically confirmed bilateral ovaries did not differ from XX female controls with respect to serological H-Y antigen, i.e. they were H-Y negative. The true hermaphrodites were H-Y positive, though H-Y antigenic activity was intermediate to male and female controls in the majority of cases. The findings support a relationship between the presence of serological H-Y antigen and gonadal status.

Serological H-Y antigen in the female chicken occurs during gonadal differentiation.

In the chicken, serological H-Y antigen is specific for the female sex. Male gonad differentiation can be experimentally influenced by estrogens, resulting in the transient formation of an ovotestis. The sex-inverted gonad becomes positive for H-Y antigen. Therefore, the question arises whether, in normal gonadogenesis also, the female gonad at the indifferent stage, before estrogens are produced, is negative for H-Y antigen. Here we show that this is indeed the case. The female gonad becomes positive for H-Y antigen when the ovary starts its organotypic differentiation at about day 6 1/2 of embryonal development. It is assumed that estrogens are responsible for the occurrence of H-Y antigen. This finding supports the view that H-Y antigen plays a role in primary ovogenesis in the chicken.

Absence of Y-specific DNA sequences in human 46,XX true hermaphrodites and in 45,X mixed gonadal dysgenesis.

A search for Y-specific DNA sequences has been performed in a sample of seven 46,XX true hermaphrodites and one 45,X mixed gonadal dysgenesis case and compared with a sample of 11 XX males. Using six Y-specific DNA probes no hybridization signal was obtained in the hermaphrodite group; in contrast, all XX males gave a positive signal with at least one probe. This difference is statistically highly significant. We conclude that the aetiology of true hermaphroditism is different from that of the XX male syndrome. As all cases of the hermaphrodite group are positive for the serological sex-specific antigen (Sxs) it is concluded that this antigen can be present even in the absence of Y-specific DNA.

Linkage studies in a pedigree with Van der Woude syndrome.

A kindred segregating for Van der Woude syndrome (VWS) through five generations is described. Biochemical and serological phenotypes at 36 polymorphic marker loci have been determined, of which 27 were informative for linkage analysis to the VWS gene (LIPED 3 computer programme). Lod scores are reported and show exclusion of close linkage for most of the marker loci. Only VWS:Duffy (Fy) resulted in uniformly positive lod scores (theta = 0.0, z(theta) = 1.31).

The occurrence of serological H-Y antigen (Sxs antigen) in the diandric protogynous wrasse, Coris julis (L.) (Labridae, Teleostei).

The serological sex-specific (Sxs) antigen (previously called 'H-Y antigen') has been shown, in various vertebrate species ranging from fish to mammals, to be characteristic of the heterogametic sex. We studied a protogynous hermaphrodite, Coris julis, in order to examine whether the change of a female to a secondary male also involves a change in the Sxs-antigen phenotype. The (homogametic) females of this species were found to be Sxs negative, while both primary and secondary males were Sxs positive. This was true not only for gonads but also for nongonadal tissues. The administration of androgen to females is known to cause sex inversion in this species; we were able to demonstrate this again at the histological level, and found that androgen results in a Sxs positive phenotype in all tissues studied (gonads, spleen, muscle). We propose that androgen is responsible, directly or indirectly, for the occurrence of the Sxs antigen.

Coagulation factor XIII: genetic linkage studies with F13B.

Linkage relations of the F13B gene with 38 marker genes are analyzed, which, along with the data of earlier reports on the same subject, brings the number of comparisons to a total of 49. Practically all the lod scores are totally negative. This will mean that the F13B gene can hardly be located on the chromosomes/chromosome arms 1p, 2p, 4q, 6p, 14p, 15p, 20q, 21p, 22 and also not on longer segments of 3q, 6q, 7q, 9p, 9q, 11q, 13q, 14q, 16p, and 16q.

Serologically H-Y antigen-negative XO mice.

In a series of six independent experiments organ homogenates of 35 mice of the XX, XO or XY sex chromosome constitutions were absorbed using three different anti-H-Y antisera raised in inbred female LEW rats. Residual activities of absorbed antisera were tested in the Raji cell, complement-dependent, cytotoxicity test. Homogenates of various tissues, including the gonads, of XX and XO females were equally unable to absorb H-Y antibodies, indicating that tissues of these mice do not carry the H-Y antigen. In contrast, XY male homogenates fully absorbed H-Y antibodies of antisera at concentrations of 1/2 to 1/4. We discuss our findings with special attention to the problem of the existence of one or more H-Y antigens and, to the genetic regulation of the expression of this antigen.

A male with a monocentric Yq isochromosome and presence of a Yp-specific DNA sequence.

We describe clinical features and laboratory findings in a physically and mentally retarded male with underdeveloped testes, a seemingly monocentric isochromosome of Yq but the presence of a Yp-specific DNA sequence at a single dose of unknown genomic localisation, and the presence of H-Y antigen at normal male titer. Our data contribute to the fine mapping of the human Y chromosome by correlating phenotypic features with results from karyotypic, immunologic, and molecular hybridisation analyses.