European genetic study on rheumatoid arthritis: is there a linkage of the interleukin-1 (IL-1), IL-10 or IL-4 genes to RA?

The genetic predisposition for rheumatoid arthritis (RA) is only partly explained by the HLA locus and most genetic factors involved in the susceptibility (and/or severity) of the disease await further identification. The first European genome scan in RA families provided suggestive evidence for linkage with a region (3.1/3q13) on chromosome 3, but many other potential RA susceptibility genes have yet to be analysed.

AIMS

To perform a linkage analysis with microsatellite markers located in the vicinity of the interleukin-1 (IL-1) gene superfamily, the IL-10 gene and the IL-4 gene cluster which might be considered putative candidate loci for RA.

METHODS

107 Caucasoid European RA sibpairs from 90 nuclear families were genotyped for markers flanking the genes for the IL-1 superfamily, IL-10 and the IL-4 gene cluster. Linkage analysis based on the identity by descent (IBD) in affected siblings was analysed with the program SIBPALNA. Affected sibpairs were stratified according to the identity by state (IBS) for three markers in the HLA region (DRB1 oligotyping, D6S276 and TNFa microsatellites) and to the presence/absence of erosive disease on X-ray examination.

RESULTS

Analysis of the whole family set showed an excess of allele sharing for markers of the IL-1 gene cluster (IBD 60%; P = 0.012) but not for IL-10 or IL-4. After stratification, the evidence of linkage to IL-1 was restricted to HLA concordant sibpairs (n = 32; IBD 70%; P = 0.006). Some evidence of linkage to IL-10 was also observed in HLA concordant sibpairs (IBD 66%; P = 0.03) and in sibpairs with erosive disease (n = 61; IBD 62%; P = 0.02).

CONCLUSIONS

We found suggestive evidence of linkage of RA to the IL-1 locus. The increased linkage to IL-1 and IL-10 in HLA-identical sibs suggests a possible interaction between these cytokines and the HLA loci. Moreover IL-10 could interact with HLA factors in predisposing to erosive disease. These results need to be tested in additional families for consistency and replication.

Evidence for digenic inheritance in a family with both febrile convulsions and temporal lobe epilepsy implicating chromosomes 18qter and 1q25-q31

We report a clinical and genetic study of a French family among whom febrile convulsions (FC) are associated with subsequent temporal lobe epilepsy (TLE) in the same individual, without magnetic resonance imaging-identifiable hippocampal abnormalities. Linkage analyses excluded the loci FEB1 and FEB2, previously implicated in FC; the GEFS+1 locus responsible for generalized epilepsy with febrile seizures plus; and the locus implicated in lateral temporal lobe epilepsy. After scanning the entire genome, significant lod scores (>3) for markers on 18qter and suggestive lod scores (>2) for markers on 1q25-q31 were obtained. An analysis of the haplotypes at these two loci supported the hypothesis that two genes segregated with the phenotype. All patients shared common haplotypes for both 1q25-q31 and 18qter chromosomes. All but one unaffected at-risk individuals carried only one, or none, of the disease haplotypes. Under the assumption of digenic inheritance, haplotype reconstruction defined a 26 cM interval on chromosome 1 and a 10 cM interval on chromosome 18. This family suggests that the association between FC and TLE may be observed in the absence of hippocampal structural abnormalities and that they may have, in some cases, a common genetic basis.

Autosomal recessive spastic ataxia of Charlevoix-Saguenay in two unrelated Turkish families

Autosomal recessive spastic ataxia of Charlevoix-Saguenay is an early onset form of hereditary spastic paraplegia with a peculiar clinical presentation. In addition to cerebellar findings which manifest first with ataxic gait in early life and spasticity, on an evolutionary basis, there is axonal neuropathy, prominent myelinated fibers in the optic fundus, and evidence of cerebellar atrophy that can be detected by cranial MRI. Intelligence is usually normal, however lower IQs have also been documented. This disorder mainly originates from the Charlevoix-Saguenay region of Quebec. Here, we report two Turkish families linked to the disease locus on chromosome 13 q12. There was homozygosity and segregation of disease haplotypes in both families. This form of spastic ataxia may be more common than originally presumed.

First genetic evidence of GABA(A) receptor dysfunction in epilepsy: a mutation in the gamma2-subunit gene

Major advances in the identification of genes implicated in idiopathic epilepsy have been made. Generalized epilepsy with febrile seizures plus (GEFS+), benign familial neonatal convulsions and nocturnal frontal lobe epilepsy, three autosomal dominant idiopathic epilepsies, result from mutations affecting voltage-gated sodium and potassium channels, and nicotinic acetylcholine receptors, respectively. Disruption of GABAergic neurotransmission mediated by gamma-aminobutyric acid (GABA) has been implicated in epilepsy for many decades. We now report a K289M mutation in the GABA(A) receptor gamma2-subunit gene (GABRG2) that segregates in a family with a phenotype closely related to GEFS+ (ref. 8), an autosomal dominant disorder associating febrile seizures and generalized epilepsy previously linked to mutations in sodium channel genes. The K289M mutation affects a highly conserved residue located in the extracellular loop between transmembrane segments M2 and M3. Analysis of the mutated and wild-type alleles in Xenopus laevis oocytes confirmed the predicted effect of the mutation, a decrease in the amplitude of GABA-activated currents. We thus provide the first genetic evidence that a GABA(A) receptor is directly involved in human idiopathic epilepsy.

Mutations in the gene encoding SLURP-1 in Mal de Meleda

Mal de Meleda (MDM) is a rare autosomal recessive skin disorder, characterized by transgressive palmoplantar keratoderma (PPK), keratotic skin lesions, perioral erythema, brachydactyly and nail abnormalities. We report the refinement of our previously described interval of MDM on chromosome 8qter, and the identification of mutations in affected individuals in the ARS (component B) gene, encoding a protein named SLURP-1, for secreted Ly-6/uPAR related protein 1. This protein is a member of the Ly-6/uPAR superfamily, in which most members have been localized in a cluster on chromosome 8q24.3. The amino acid composition of SLURP-1 is homologous to that of toxins such as frog cytotoxin and snake venom neurotoxins and cardiotoxins. Three different homozygous mutations (a deletion, a nonsense and a splice site mutation) were detected in 19 families of Algerian and Croatian origin, suggesting founder effects. Moreover, one of the common haplotypes presenting the same mutation was shared by families from both populations. Secreted and receptor proteins of the Ly-6/uPAR superfamily have been implicated in transmembrane signal transduction, cell activation and cell adhesion. This is the first instance of a secreted protein being involved in a PPK.

Clinical and genetic studies of 3 large, consanguineous, Algerian families with Mal de Meleda

BACKGROUND

Mal de Meleda (MIM 248300), also referred to as keratosis palmoplantaris transgrediens of Siemens, is a rare autosomal recessive skin disorder with a prevalence in the general population of 1 in 100,000. The main clinical characteristics are transgressive palmoplantar keratoderma, hyperhidrosis, and perioral erythema, but there are also associated features such as brachydactyly, nail abnormalities, and lichenoid plaques.

OBSERVATIONS

We studied the clinical and genetic characteristics of 3 large, consanguineous, Algerian families, including 14 affected individuals. Homozygosity mapping of the third family confirmed localization of the responsible gene to 8qter in all 3 families.

CONCLUSIONS

Although some differences in phenotypic expression among subjects were noted, genetic analysis of the 3 families who shared a common ethnic background indicated that a single gene is responsible for mal de Meleda in this population.

Genome search for susceptibility loci of common idiopathic generalised epilepsies

Genetic factors play a major role in the aetiology of idiopathic generalised epilepsies (IGEs). The present genome scan was designed to identify susceptibility loci that predispose to a spectrum of common IGE syndromes. Our collaborative study included 130 IGE-multiplex families ascertained through a proband with either an idiopathic absence epilepsy or juvenile myoclonic epilepsy, and one or more siblings affected by an IGE trait. In total, 413 microsatellite polymorphisms were genotyped in 617 family members. Non-parametric multipoint linkage analysis, using the GeneHunter program, provided significant evidence for a novel IGE susceptibility locus on chromosome 3q26 (Z(NPL) = 4.19 at D3S3725; P = 0.000017) and suggestive evidence for two IGE loci on chromosome 14q23 (Z(NPL) = 3.28 at D14S63; P = 0.000566), and chromosome 2q36 (Z(NPL) = 2.98 at D2S1371; P = 0.000535). The present linkage findings provide suggestive evidence that at least three genetic factors confer susceptibility to generalised seizures in a broad spectrum of IGE syndromes. The chromosomal segments identified harbour several genes involved in the regulation of neuronal ion influx which are plausible candidates for mutation screening.

Noninherited maternal antigens do not play a role in rheumatoid arthritis susceptibility in Europe. European Consortium on Rheumatoid Arthritis Families

OBJECTIVE

It has been proposed that noninherited maternal antigens (NIMA) (HLA-DR antigens) might play a role in susceptibility to rheumatoid arthritis (RA), especially in patients who are not genetically predisposed, such as those who are HLA-DR4 and/or shared epitope (SE) negative. The present study was undertaken to test the NIMA hypothesis in a large cohort of European RA patients assembled by the European Consortium on RA Families (ECRAF).

METHODS

HLA-DRB1 oligotyping was performed in families of European RA patients for whom both parents were alive. These families were consecutively recruited by the ECRAF between 1996 and 1998, for association studies. The frequencies of HLA-DR NIMA were compared with those of the noninherited paternal antigens (NIPA) after stratification for HLA-DR*04, *0401 and/or *0404, and SE status. NIMA or NIPA that coincided with inherited HLA-DR antigens were considered redundant and excluded from analysis. Calculations concerning the whole group and restricted to patients lacking parental RA were performed.

RESULTS

One hundred seventy families from France (n = 81), Belgium (n = 23), Spain (n = 24), Italy (n = 19), Portugal (n = 14), and The Netherlands (n = 9) were oligotyped. The group of probands was predominantly female (88%), positive for rheumatoid factor, DR*04, and SE (71%, 58%, and 75%, respectively), and had erosive disease (75%). Parental RA was reported in 21 families. Using the NIPA as control, the frequency of HLA-DRB1*04, *0401 and/or *0404-, or SE-positive NIMA was not found to be increased in patients lacking these susceptibility alleles. The same was true when the 21 probands with parental RA were excluded from analysis. In DRB1*04-positive patients, we found no evidence of a relevant effect of HLA-DR3 or DR6 in the NIMA.

CONCLUSION

Our results do not support the notion that noninherited maternal antigens have a role in susceptibility to RA in the offspring.

Spectrum of SPG4 mutations in autosomal dominant spastic paraplegia

Autosomal dominant hereditary spastic paraplegia (AD-HSP) is a group of genetically heterogeneous neurodegenerative disorders characterized by pro- gressive spasticity of the lower limbs. Five AD-HSP loci have been mapped to chromosomes 14q, 2p, 15q, 8q and 12q. The SPG4 locus at 2p21-p22 has been shown to account for approximately 40% of all AD-HSP families. SPG4 encoding spastin, a putative nuclear AAA protein, has recently been identified. Here, sequence analysis of the 17 exons of SPG4 in 87 unrelated AD-HSP patients has resulted in the detection of 34 novel mutations. These SPG4 mutations are scattered along the coding region of the gene and include all types of DNA modification including missense (28%), nonsense (15%) and splice site point (26.5%) mutations as well as deletions (23%) and insertions (7.5%). The clinical analysis of the 238 mutation carriers revealed a high proportion of both asymptomatic carriers (14/238) and patients unaware of symptoms (45/238), and permitted the redefinition of this frequent form of AD-HSP.

Two new loci for autosomal recessive ichthyosis on chromosomes 3p21 and 19p12-q12 and evidence for further genetic heterogeneity

Autosomal recessive ichthyosis (ARI) includes a heterogeneous group of disorders of keratinization characterized by desquamation over the whole body. Two forms largely limited to the skin have been defined: lamellar ichthyosis (LI) and nonbullous congenital ichthyosiform erythroderma (NCIE). A first gene for LI, transglutaminase TGM1, has been identified on chromosome 14, and a second one has been localized on chromosome 2. In a genomewide scan of nine large consanguineous families, using homozygosity mapping, two new loci for ARI were found, one for a lamellar form in a 6-cM interval on chromosome 19 and a second for an erythrodermic form in a 7.7-cM interval on chromosome 3. Linkage to one of the four loci could be demonstrated in more than half of 51 consanguineous families, most of them from the Mediterranean basin. All four loci could be excluded in the others, implying further genetic heterogeneity in this disorder. Multipoint linkage analysis gave maximal LOD scores of 11.25 at locus D19S566 and 8.53 at locus D3S3564.

Spastin, a new AAA protein, is altered in the most frequent form of autosomal dominant spastic paraplegia

Autosomal dominant hereditary spastic paraplegia (AD-HSP) is a genetically heterogeneous neurodegenerative disorder characterized by progressive spasticity of the lower limbs. Among the four loci causing AD-HSP identified so far, the SPG4 locus at chromosome 2p2-1p22 has been shown to account for 40-50% of all AD-HSP families. Using a positional cloning strategy based on obtaining sequence of the entire SPG4 interval, we identified a candidate gene encoding a new member of the AAA protein family, which we named spastin. Sequence analysis of this gene in seven SPG4-linked pedigrees revealed several DNA modifications, including missense, nonsense and splice-site mutations. Both SPG4 and its mouse orthologue were shown to be expressed early and ubiquitously in fetal and adult tissues. The sequence homologies and putative subcellular localization of spastin suggest that this ATPase is involved in the assembly or function of nuclear protein complexes.

Autosomal dominant nocturnal frontal lobe epilepsy in a Spanish family with a Ser252Phe mutation in the CHRNA4 gene

BACKGROUND

A large family with autosomal dominant nocturnal frontal lobe epilepsy from the south of Spain was studied. The clinical appearance of the disease in this family, which included 28 members, of whom 11 were affected and 2 were obligate carriers, was identical to that previously described in an Australian family and a Norwegian family, in which mutations in exon 5 of the CHRNA4 gene were found.

METHODS

Following DNA extraction, the family was genotyped with 4 fluorescent markers flanking the locus to the CHRNA4 gene on chromosome 20q13.3, and lod score computations were performed. The exon 5 of the CHRNA4 gene was amplified between nucleotides 535 and 825 and polymerase chain reaction products were purified and sequenced directly.

RESULTS

The same missense mutation as that found in the Australian family, C-->T, which causes the replacement of a serine with phenylalanine in amino acid 252 in exon 5, was detected. This mutation segregated with the disorder in all 11 affected members, in the 2 obligate carriers, and in 1 asymptomatic sibling, and was not found in 1 spouse and 1 daughter. Neither of the 2 polymorphisms found in a series of families with epilepsy were found in our sample [corrected].

CONCLUSIONS

These data confirm the clinical homogeneity in the phenotypic expression of autosomal dominant nocturnal frontal lobe epilepsy caused by mutation in the CHRNA4 gene, and the pathogenic role of the Ser252Phe mutation in this disorder.

Clinical heterogeneity of autosomal recessive spastic paraplegias: analysis of 106 patients in 46 families

BACKGROUND

Hereditary spastic paraplegias (HSPs) are a heterogeneous group of neurodegenerative disorders characterized by progressive and predominant spasticity of the lower limbs, in which dominant, recessive, and X-linked forms have been described. While autosomal dominant HSP has been extensively studied, autosomal recessive HSP is less well known and is considered a rare condition.

OBJECTIVE

To analyze the clinical presentation in a large group of patients with autosomal recessive HSP from Portugal and Algeria to define homogeneous groups that could serve as a guide for future molecular studies.

RESULTS

Clinical features in 106 patients belonging to 46 Portuguese and Algerian families with autosomal recessive HSP are presented, as well as the results of molecular studies in 23 of these families. Five phenotypes are defined: (1) pure early-onset families, (2) pure lateonset families, (3) complex families with mental retardation, (4) complex families with mental retardation and peripheral neuropathy, and (5) complex families with cerebellar ataxia. Six additional families have specific complex presentations, each of which is unique in the present series. Pyramidal signs in the upper limbs and pes cavus are frequent findings, while pseudobulbar signs, including dysarthria, dysphagia, and brisk jaw jerks, are more frequent in the complex forms. The complex forms have a poorer prognosis, while pure forms, particularly those with early onset, are more benign. One Algerian pure early-onset kindred was linked to the locus on chromosome 8, previously reported in 4 Tunisian families. Two of the Portuguese kindreds with complex forms (one with mental retardation and the other associated with hypoplasia of the corpus callosum) showed linkage to the locus recently identified on chromosome 16.

CONCLUSIONS

Although autosomal recessive HSP represents a heterogeneous group of diseases, some phenotypes can be defined by analyzing a large group of patients. The fact that only one Algerian family was linked to chromosome 8 suggests that this is a rare localization even in kindreds with the same ethnic background. Linkage to chromosome 16 was found in 2 clinically diverse Portuguese kindreds, illustrating that this locus is also rare and may correspond to different phenotypes.

Autosomal dominant lateral temporal epilepsy: clinical and genetic study of a large Basque pedigree linked to chromosome 10q

We report a large family with a temporal partial epilepsy syndrome inherited in an autosomal dominant mode, with a penetrance of about 80%. This epilepsy syndrome is benign, with age of onset in the second or third decade of life. It is characterized by rare partial seizures, usually secondarily generalized, arising mostly during sleep, without postictal confusion. There is a good response to the antiepileptic therapy but often a recurrence of seizures after drug withdrawal. The partial component, visual (lights, colors, and simple figures) or auditory (buzzing or "humming like a machine"), the existence of temporo-occipital interictal electroencephalographic epileptiform abnormalities, and the hypoperfusion in the temporal lobe detected by interictal hexamethylpropyleneamine oxime-technetium 99m (HMPAO-Tc99m) single-photon emission computed tomography, strongly suggest a lateral temporal lobe origin. The genetic analysis found linkage to chromosome 10q, and localized a gene in a 15-cM interval that overlaps a previously found localization for partial epilepsy in a large three-generation family. This syndrome could be called autosomal dominant lateral temporal epilepsy.

Genetic linkage of Meleda disease to chromosome 8qter

Meleda disease (mal de Meleda) MIM *248300 is an autosomal recessive disorder, clinically characterised by transgressive palmoplantar keratoderma, hyperhidrosis and perioral erythema. It was first described on the Adriatic island of Meleda, where it was relatively common. The prevalence in the general population is estimated to be 1 in 100,000. Linkage analysis of two large consanguineous families from Algeria, including 10 affected individuals, showed strong evidence for localisation of Meleda disease to chromosome 8qter with a maximum two-point lod score for D8S1751 of 8.21 at theta = 0. Analysis of homozygosity regions and recombination events places the gene in a region of at least 3 cM, telomeric to D8S1727. A common haplotype was observed in the two families, suggesting a founder effect.

New susceptibility locus for rheumatoid arthritis suggested by a genome-wide linkage study

Rheumatoid arthritis (RA), the most common autoimmune disease, is associated in families with other autoimmune diseases, including insulin-dependent diabetes mellitus (IDDM). Its genetic component has been suggested by familial aggregation (lambdas = 5), twin studies, and segregation analysis. HLA, which is the only susceptibility locus known, has been estimated to account for one-third of this component. The aim of this paper was to identify new RA loci. A genome scan was performed with 114 European Caucasian RA sib pairs from 97 nuclear families. Linkage was significant only for HLA (P < 2.5.10(-5)) and nominal for 19 markers in 14 other regions (P < 0.05). Four of the loci implicated in IDDM potentially overlap with these regions: the putative IDDM6, IDDM9, IDDM13, and DXS998 loci. The first two of these candidate regions, defined in the RA genome scan by the markers D18S68-D18S61-D18S469 (18q22-23) and D3S1267 (3q13), respectively, were studied in 194 additional RA sib pairs from 164 nuclear families. Support for linkage to chromosome 3 only was extended significantly (P = 0.002). The analysis of all 261 families provided a linkage evidence of P = 0. 001 and suggested an interaction between this putative RA locus and HLA. This locus could account for 16% of the genetic component of RA. Candidate genes include those coding for CD80 and CD86, molecules involved in antigen-specific T cell recognition. In conclusion, this first genome scan in RA Caucasian families revealed 14 candidate regions, one of which was supported further by the study of a second set of families.

Genetic linkage of progressive pseudorheumatoid dysplasia to a 3-cM interval of chromosome 6q22

Progressive pseudorheumatoid dysplasia (PPD), MIM 208230, is an autosomal-recessive disorder, clinically characterized by spondyloepiphyseal dysplasia and progressive arthropathy. Linkage analysis of three families of different geographic and ethnic origin, including 11 affected individuals, showed strong evidence for localization of a gene for progressive pseudorheumatoid dysplasia to chromosome 6q with a maximum two-point lod score for D6S1647 of 8.34 at theta=0. Analysis of regions of homozygosity placed the gene in a 3-cM interval between D6S 1594 and D6S432. No significant shared haplotype was found for markers of the linked interval in the three families analyzed. Five genes encoding collagen and one encoding a specific procollagen-processing enzyme that map near this interval represent good candidates for the PPD gene.

[Clinical and molecular genetic analysis of 4 Swiss families with the pure form of hereditary spastic spinal paralysis]

Hereditary spastic paraplegia (HSP) is a rare neurodegenerative disease of the spinal cord with a progressive gait disorder, associated with other neurological abnormalities in the complicated form. A cluster of families with this disorder in the central part of the country has long been known to Swiss neurologists. In the present report, we describe our clinical and molecular findings in four large families originating from this region and suffering from a pure HSP form. Clinical presentation was similar in the four families. The age of onset varied widely from 2 to 70 years with the appearance of a gait disorder, which slowly progressed to wheelchair confinement after 30-70 years. No other neurological abnormality was found except for impairment of the vibration sense and sphincter abnormalities. In three families an association with markers of the SPG4 locus on chromosome 2 was found. In the fourth, the largest one, no linkage could be found with either SPG4, or with the other two known loci, SPG3 on chromosome 14 and SPG6 on chromosome 15. These data demonstrate the genetic heterogeneity in HSP, even in families from the same region. They also suggest the presence of at least one additional locus for the pure form.

Mapping of a complicated familial spastic paraplegia to locus SPG4 on chromosome 2p

Autosomal dominant familial spastic paraplegia (AD-FSP) is a degenerative disorder of the central motor system characterised by progressive spasticity of the lower limbs. AD-FSP has been divided into pure and complicated forms. Pure AD-FSP is genetically heterogeneous; three loci have been mapped to chromosomes 14q (SPG3), 2p (SPG4), and 15q (SPG6), whereas no loci responsible for complicated forms have been identified to date. Here we report linkage to the SPG4 locus in a three generation family with AD-FSP complicated by dementia and epilepsy. Assuming that both forms of AD-FSP are caused by mutations involving the same FSP gene, analysis of recombination events in this family positions the SPG4 gene within a 0 cM interval flanked by loci D2S2255 and D2S2347.

Association of rheumatoid arthritis with an amino acid allelic variation of the T cell receptor

OBJECTIVE

To investigate allelic variations of T cell receptor residues for a contribution to rheumatoid arthritis (RA) susceptibility.

METHODS

We conducted an RA case-control study involving 1,579 northwest Europeans: 766 patients with erosive and rheumatoid factor-positive disease and 813 control subjects. Productive changes of segments TCRAV6S1, TCRAV7S1, TCRAV8S1, TCRAV10S2, and TCRBV6S1, TCRBV6S7 were investigated by single-strand conformation polymorphisms. The TCRAV8S1 association was confirmed by restriction fragment length polymorphism.

RESULTS

In the systematic study (77 patients and 119 controls), an increase in 1 TCRAV8S1 genotype was found in the RA patients (P = 0.0004). This finding was replicated in 2 further populations, one from France (212 patients and 254 controls) and the other from Britain (477 patients and 440 controls), with a similar odds ratio (OR), which allowed pooling of the data and confirmation of the association (OR 1.3 [95% confidence interval 1.1-1.7], P = 0.008).

CONCLUSION

These findings show evidence that TCRA is an RA susceptibility locus.

Mapping of Papillon-Lefevre syndrome to the chromosome 11q14 region

Papillon-Lefevre syndrome (PLS) is an autosomal recessive disease which belongs to the palmo-plantar keratoderma (PPK) group. It is characterized by a premature loss of primary and permanent teeth and early onset periodontitis. High consanguinity has been observed in over one-third of PLS families. No candidate genes or gene localizations have been described to date for this disorder. A primary genome-wide search by homozygosity mapping using samples from a large consanguineous family in which 4 siblings were affected by the disease showed homozygosity and linkage in the region of 11q14. Linkage was confirmed in 4 additional families with diverse ethnic and geographic backgrounds, 2 of which were consanguineous. A maximum two-point lod score of 8.19 was obtained for the marker AFM063yg1 (D11S901= for theta = 0. Analysis of recombination events places the gene within a 7-cM interval between AFM063yg1 and AFM269yg9 (D11S4175). No shared haplotype was found for the 5 families analysed.

Phenotype of autosomal dominant spastic paraplegia linked to chromosome 2

We report the clinical features of 12 families with autosomal dominant spastic paraplegia (ADSP) linked to the SPG4 locus on chromosome 2p, the major locus for this disorder that accounts for approximately 40% of the families. Among 93 gene carriers, 32 (34%) were unaware of symptoms but were clinically affected. Haplotype reconstruction showed that 90% of the asymptomatic gene carriers presented increased reflexes and/or extensor plantar responses independent of age at examination. The mean age at onset was 29 years, ranging from 1 to 63 years. Intra- as well as inter-familial variability of age at onset was important, but did not result from anticipation. Phenotype-genotype correlations and comparison with SPG3 and SPG5 families indicated that despite the variability of age at onset, SPG4 is a single genetic entity but no clinical features distinguish individual SPG4 patients from those with SPG3 or SPG5 mutations.

A radiation hybrid map of the human genome

We have developed a panel of whole-genome radiation hybrids by fusing irradiated diploid human fibroblasts with recipient hamster cells. This panel of 168 cell lines has been typed with microsatellite markers of known genetic location. Of 711 AFM genetic markers 404 were selected to construct a robust framework map that spans all the autosomes and the X chromosome. To demonstrate the utility of the panel, 374 expressed sequence tags (ESTs) previously assigned to chromosomes 1, 2, 14 and 16 were localized on this map. All of these ESTs could be positioned by pairwise linkage to one of the framework markers with a LOD score of greater than 8. The whole genome radiation hybrid panel described here has been used as the starting material for the Genebridge4 panel that is being made widely available for genome mapping projects.

Autosomal recessive lamellar ichthyosis: identification of a new mutation in transglutaminase 1 and evidence for genetic heterogeneity

Autosomal recessive lamellar ichthyosis (ARLI) belongs to the group of congenital disorders of cornification. It is characterized by a severe and generalized ichthyosis, and other variable cutaneous signs. The human transglutaminase 1 (TGM1) gene was recently found to be the disease-causing gene. Linkage analysis in 23 families (of which 13 were consanguineous) showed that for 10 of them, the disease was linked to the TGM1 gene. A new deleterious mutation introducing a stop codon in the TGM1 reading frame was found. Nevertheless, for the 13 other ARLI families, TGM1 was found to be unlinked to the disease. The present data show that ARLI is genetically heterogeneous and confirm that TGM1 is one of the responsible genes.

Immunohistochemistry of pS2 in normal human breast and in various histological forms of breast tumours

Expression of pS2 was studied by immunocytochemistry in normal breast tissue (n = 20), benign tumours (n = 9) and 145 breast cancers representative of the different histological types. pS2 immunostaining was scored as negative (D1 = 0-5% stained cells), positive (D2 = 5-75% stained cells) or highly positive (D3 > 75% stained cells). pS2 protein was evident in all normal breast samples examined. Six of nine benign lesions showed pS2 staining. In both cases, immunostaining was weaker than in breast cancers. Of breast cancers, 77/145 (53.1%) were pS2 positive, including 33.1% with intense staining. The presence of pS2 was not correlated with the age of patients, the size of the primary tumour, or lymph node status, but was correlated with histological grading and nuclear grading. pS2 expression was also correlated with menopausal status and oestrogen receptor status (59% of receptor-positive tumours were pS2 positive), but not to progesterone receptor status. pS2 expression in breast carcinomas is not a characteristic of specific histological types. Although this protein is predominantly expressed in oestrogen receptor-positive and differentiated tumours, it shows oestrogen-independent expression in about 30% of cases.

Enzyme-linked immunosorbent assay of pS2 in breast cancers, benign tumors, and normal breast tissues. Correlation with prognosis and adjuvant hormone therapy

An enzyme-linked immunosorbent assay using monoclonal and polyclonal antibodies against recombinant pS2 was devised. It was used to measure pS2 concentration in the cytosol of 339 breast cancer, 15 fibroadenomas, 16 cases of benign breast disease, and 6 normal breast tissues. The mean value of pS2 concentration was higher in cancer, but the protein could be detected readily in benign tumors and even in normal breast. The concentration of pS2 was significantly lower in postmenopausal women and tumors of differentiation Grade 3. The pS2 concentration was correlated strongly with the presence of estrogen receptors (ER) and progesterone receptors (PR). No correlation was observed with the size, histologic type of the tumor, and lymph node status. The prognostic value of pS2 appeared relatively limited. It was clear cut only for a relatively small group of patients (approximately 15%), who had low concentrations of pS2 (less than or equal to 0.32 ng/mg of protein). These patients had a shorter disease-free interval and overall survival time. The most striking correlation was observed with the outcome of adjuvant hormone therapy. pS2 concentration was shown to be the most potent prognostic factor, preceding even ER.

Modulation of proliferation, estradiol receptors and estrogen regulated protein PS2/BCEI in human breast cancer cell lines by gamma interferon

The effects of recombinant gamma interferon (IFN gamma) on proliferation, estrogen-receptor (ER) content, mRNA level and protein secretion of a breast cancer estrogen-induced protein pS2/BCEI were investigated in two human breast cancer cell lines, ZR75-1 and T47D. Both cell lines have estrogen and progesterone receptors and previously showed HLA class I and class II responses to IFN gamma (Int J Cancer 1990; 45: 1169). An antiproliferative effect of IFN gamma (1000-5000 U/ml) was observed in serum containing medium on ZR75-1 but not on T47D cells. Noninhibitory concentration of IFN gamma (100 U/ml) had sensitising antiproliferative effect with antiestrogens on ZR75-1 cells whereas IFN gamma did not modify the growth inhibition observed in T47D cells with antiestrogens. In serum-free, estradiol-free, phenol-red-free chemically defined medium (Cancer Res 1984; 44: 4553), IFN gamma abolished in ZR75-1 but not in T47D the 30% growth stimulation induced by estradiol. In ZR75-1 cells, IFN gamma induced a transitory 30-50% increase of ER content, as measured by ER-enzymoimmunoassay, at day 2 of culture, and reduced mRNA level and secretion of pS2/BCEI. In T47D cells, a 30-50% decrease of ER content was observed but only when cells were long term cultured (30 weeks) with IFN gamma. In this cell line, no transcription of pS2/BCEI was observed. Antiproliferative action of IFN gamma on ZR75-1 cells is associated with an inhibition of estradiol effects and a reduction of pS2/BCEI mRNA level and protein secretion.

Monoclonal antibodies against native ant denatured forms of estrogen-induced breast cancer protein (BCEI/pS2) obtained by expression in Escherichia coli

Several vectors were used to express the complementary DNA for breast cancer estrogen-induced protein BCEI (also called pS2) in Escherichia coli. The best results were obtained by using the pUR 290 expression vector after deletion of the sequence encoding the signal peptide of the protein. In these conditions, beta-galactosidase-BCEI/pS2 fusion protein accounted for approximately 20% of total proteins in bacterial extracts. It was purified by chromatography on DEAE-Trisacryl or by gel electrophoresis and electroelution. Polyclonal antibodies were obtained by immunization of rabbits and goats, and monoclonal antibodies were raised in mice. Two types of monoclonal antibodies were obtained: one class recognized the native protein and was very efficient for the immunoprecipitation and immunopurification of the protein from breast cancer cells; a second class recognized the denatured protein and was especially effective for immunoblot studies. BCEI/pS2 could be detected by immunocytochemistry in breast cancer biopsies using monoclonal antibodies on frozen or paraffin-embedded sections. One of the antibodies (mBCEI11) exhibited high affinity for the protein and could be used at 1.9 micrograms/ml concentration for immunolabeling of histological sections. The mBCEI11 antibody was used in immunoaffinity chromatography to purify the peptide in a single step from culture media of estrogen-treated MCF-7 cells.

Cloning of a gene expressed in human breast cancer and regulated by estrogen in MCF-7 cells

Messenger RNAs (mRNAs) were prepared from MCF-7 breast cancer cells grown in the presence of estradiol. Complementary DNAs (cDNAs) were inserted into pBR322 plasmid and a library of 4400 recombinant bacterial clones was prepared. The clones were screened by in situ differential hybridization with cDNAs prepared from RNAs of MCF-7 cells grown either in the presence or absence of estradiol. Several estrogen-induced or estrogen-repressed clones were identified. One of them corresponded to a relatively frequent mRNA (0.8% of recombinant plasmids) of 650 nucleotides. The concentration of this mRNA was increased by estradiol (half maximal induction approximately 0.05 nM) but not by progesterone, dexamethasone, or dihydrotestosterone. Tamoxifen inhibited the effect of estradiol but was devoid of any agonistic activity when administered separately. This messenger was present in biopsies of breast cancer, but not in endometrium or liver. The cloned cDNA was sequenced. An open reading frame was found corresponding to a protein of less than 100 amino acids. A search of data banks showed no identity or marked similarity to previously published DNA or protein sequences, particularly to those of growth factors evoked by some characteristics of the coded polypeptide. The cloned cDNA probe was used to screen a library of Charon 4A phage containing human genomic fragments. Screening of 300,000 phages yielded two different recombinants hybridizing to the cDNA. Southern blot experiments using DNA from recombinant phage, MCF-7 cells, and placenta showed the presence of a unique gene exhibiting a similar restriction pattern in DNAs from malignant and nonmalignant tissues.

17 beta-Hydroxysteroid dehydrogenase activity in human breast epithelial cell and fibroblast cultures

Primary cultures of human breast cells prepared from surgical specimens of reduction mammoplasty were used to study the activity of the enzyme 17 beta-hydroxysteroid dehydrogenase (E2DH) which converts estradiol (E2) into its less active metabolite estrone. This study was performed in both epithelial and stromal cells separated, after collagenase digestion of the tissue, on a Percoll gradient, and then cultured as monolayers in Ham's F 10 medium supplemented differently for epithelial cells and fibroblasts. E2DH activity was strikingly higher in epithelial cells than in fibroblasts, since after [3H]E2 incubation (2 nM), 600 fmol/micrograms DNA were metabolized to estrone in epithelial cells after 1 h, whereas an equivalent amount was hardly obtained in fibroblast cultures after 24 h. The affinity and capacity of E2DH were greater in epithelial cells with apparent Michaelis-Menten constant (Km) = 0.6 +/- 0.1 microM and maximum velocity (Vmax) = 250 to 360 pmol/micrograms DNA/h, whereas they were 10 +/- 1 microM and 50 to 70 pmol/micrograms DNA/h, respectively, in fibroblast cultures. Moreover, the E2DH activity was 2 to 5 times higher in epithelial cells cultured in the presence of the progestin medroxyprogesterone acetate, whereas it remained unchanged in fibroblasts cultured under the same conditions. This increase in E2DH activity was dose dependent from 10(-10) to 10(-7) M medroxyprogesterone acetate and inhibited by both actinomycin D and cycloheximide. This system of differential breast cell culture appears to be a fruitful tool for the study of the hormone dependence of normal breast growth and differentiation. Due to the presence of E2DH, epithelial cells are more apt to undergo and to moderate E2 action. Moreover, epithelial cells are a possible site of progesterone modulation of E2DH activity. Therefore, E2DH could be a good marker both for epithelial cells and their hormone dependence.

[Steroid hormone receptors in benign breast diseases]

Benign breast diseases generally occur in women with progesterone insufficiency and an unopposed estrogen status. This hormonal imbalance is also a main risk factor for breast cancer in the long run. The presence of estradiol and progesterone receptors in benign breast disease are additional proof of their hormone dependence. The level of receptors is higher when the epithelial cellularity is high and also in more recent lesions, and younger women. The level and subcellular location of the receptors also depend on the endogenous secretion of steroids: their level varies throughout the menstrual cycle, and it is maximal at the end of the follicular phase, due to the high estradiol secretion. The cytosol and nuclear level and location of the receptors are also modified by hormonal therapy: estrogen-progestagens given as a contraceptive, or progestins given as a substitutive and antiestrogen therapy. These modifications constitute a biochemical basis for the hormonal progestagen treatment of benign breast diseases.