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Molecular and biochemical assays were used to determine the identification of thermophilic bacilli isolated from New Zealand milk powder. One hundred and forty one isolates of thermophilic bacilli were classified into six species using biochemical profiles. Geobacillus stearothermophilus represented 56% of the isolates. All isolates were also analysed by randomly amplified polymorphic DNA (RAPD) analysis, with 45 types identified. Amplification of the 16S-23S rDNA internal spacer region produced two to eight amplification products per strain. The patterns from gel electrophoresis of the internal spacer region amplicons formed two major groupings suggesting the possibility of two distinct species. Partial sequences of 16S rDNA from representatives from each group were compared with sequences in GeneBank and were found to match the 16S rDNA sequences of B. flavothermus and G. thermoleovorans. Primers were designed for these species and used to screen an arbitrary selection of 59 of the dairy isolates. This enabled the identification of 28 isolates as B. flavothermus and 31 isolates as Geobacillus species and these appear to be the predominant isolates in the New Zealand milk powder samples examined. Comparison of the fragment pattern generated by amplification of the 16S-23S rDNA internal spacer region is a simple method to differentiate thermophilic Bacillus species associated with the dairy industry.

Aims: The major cell envelope proteinase (lactocepin; EC 3.4.21.96) produced by Lactococcus lactis cheese starter bacteria is required for starter growth and acid production in milk. The aim of this study was to characterize a lactocepin plasmid from a L. lactis subsp. cremoris cheese starter strain., Methods and Results: A restriction map of the lactocepin plasmid pHP003 from strain HP was constructed, fragments were cloned in Escherichia coli vectors, and the complete DNA sequence (13,433 bp) was determined. Among 120 industrial L. lactis starter strains screened, five contained the same specificity-type lactocepin as pHP003. The lactocepin gene in these strains was invariably linked with a partially-deleted abiB gene., Conclusion: The lactocepin specificity type of strain HP, conferred by a known configuration of key residues, is relatively uncommon. The gene is invariably linked with a partially deleted abiB gene on each lactocepin plasmid., Significance and Impact of the Study: This is the first complete sequence reported for a lactocepin plasmid, and provides the basis for better understanding, or manipulation, of lactocepin production.

Lactococcus lactis strains isolated from vegetable products transferred the ability to ferment sucrose in conjugation experiments with the recipient strain L. lactis MG1614. Nisin production and sucrose fermentation were transferred together from two strains, but transfer also occurred from several other strains which did not produce nisin. Pulsed-field gel electrophoresis analysis showed that all transconjugants had acquired large chromosomal insertions at two main sites. Nisin sucrose transconjugants had gained inserts of 70 kb, while those that fermented sucrose without nisin production contained inserts of between 50 and 110 kb. Transconjugants from one donor had acquired a separate insertion of 55 kb which correlated with enhanced bacteriophage resistance, but contained neither nisin nor sucrose fermentation genes.

Lactobacillus casei, Lact. paracasei and Lact. rhamnosus form a closely related taxonomic group within the heterofermentative lactobacilli. These three species are difficult to differentiate using traditional fermentation profiles. We have developed polymerase chain reaction primers which are specific for each of these species based on differences in the V1 region of the 16S rRNA gene. Sixty-three Lactobacillus isolates from cheese were identified using these primers. The 12 Lact. rhamnosus and 51 Lact. paracasei identified in this way were also differentiated using a randomly amplified polymorphic DNA (RAPD) primer.

Thermophilic streptococci were isolated from biofilms on stainless steel samples exposed to pasteurized skimmed milk and from dairy products from a dairy manufacturing plant. The phenotypic characters of these isolates were distinct from those of other thermophilic streptococci of dairy origin (Streptococcus thermophilus and Streptococcus bovis). Genotypic data [restriction endonuclease analysis, ribotyping, random amplified polymorphic DNA (RAPD) profiles, DNA-DNA hybridization and G + C contents] support the classification of these isolates as a new species. The sequence of the 16S rRNA was compared with that of 29 species of streptococci and shown to be significantly different. The sequence of the 16S-23S rRNA intergenic spacer region also differed from published sequences of closely related species. A fluorescent in situ hybridization probe prepared to a specific part of the 16S rRNA gene sequence was able to distinguish the unknown isolates from reference isolates of S. thermophilus and S. bovis. It is proposed that these thermophilic streptococcal isolates from a dairy environment be classified in the genus Streptococcus as a new species, Streptococcus waius (from waiu, the New Zealand Maori word for milk). The type strain is 3/1T (= NZRCC 20100T).

Lactic acid bacteria isolated from minimally processed fresh fruit and vegetable products were identified as Lactococcus lactis subsp. lactis on the basis of phenotypic tests, presence of lactococcal IS elements, and partial sequence analysis of the 16S rRNA gene. Isolated bacteria were differentiated using pulsed-field gel electrophoresis of SmaI digests of genomic DNA. Sprouted seeds were the best source of strains, and lactococci appear to be the dominant microflora on these products during the period they are intended to be eaten. Although these plant strains showed many similarities to strains of L. lactis used as dairy starter cultures, their carbohydrate fermentation patterns were unusual and probably reflect their environmental origin. Most strains fermented sucrose and xylose, and some also fermented raffinose and melibiose. Most of the bacteriocin-producing strains produced nisin, and nisin genes could also be detected in strains that showed no bacteriocin activity, or that produced a different bacteriocin with a narrow spectrum of activity. One strain produced nisin but was unable to ferment sucrose, properties that have been generally regarded as linked. These strains may have uses as biopreservatives for minimally processed plant products.

The 16S ribosomal RNA gene sequences of Lactococcus lactis ssp. lactis and ssp. cremoris differ by 9-10 bp (depending on strain), within the first 200 bp of the sequence. These differences were used to develop two methods of genetically differentiating lactis and cremoris strains. Primers to conserved sequences in the 16S rRNA gene were used in a PCR reaction to amplify fragments of the 16S rRNA gene. A single base difference at position 180 of the sequence was utilised to develop a ligase chain reaction to differentiate lactis and cremoris sequences. The second method involved digestion of the amplified fragments with restriction endonucleases specific for either the lactis or cremoris sequence. Resolution of the digested fragments on an agarose gel allowed the strains to be identified as genetically lactis or cremoris. This method was used to examine lactococci isolated from raw milk. Of 31 raw milk strains examined, 21 contained the cremoris 16S rRNA sequence, however, all 31 strains exhibited the phenotypic characteristics of the lactis subspecies.

An oligonucleotide probe was selected from the 16S rRNA gene of Clavibacter michiganensis subsp. sepedonicus for specific in situ hybridization. The rhodamine-labelled oligonucleotide probe was used in conjunction with an indirect immunofluorescence procedure based on a specific monoclonal antibody detected with a fluorescein-labelled conjugate. Simultaneous labelling of bacterial cells with the oligonucleotide and antibody probes allows accurate microscopic identification of single cells when isolation and other methods of confirming bacterial identity are not possible.

The insertion sequence (IS) ISS1 from Lactococcus lactis was amplified from lactococcal genomic DNA using a primer to the 18-bp inverted repeat sequence. The amplified product hybridized to a single EcoRI fragment in a total genomic DNA digest of Leuconostoc mesenteroides ssp. dextranicum NZDRI 2218. The DNA sequence of this ISS1-like element (IS1297) and the Le. mesenteroides sequences flanking the IS were determined and compared with other iso-ISS1 elements. No direct repeats were found immediately flanking IS1297; however, direct repeats were present approximately 60 bp on either side of the insertion site. IS1297 contained a major open reading frame (ORF) of 681 bp, encoding a putative 226-amino-acid protein with 96.5% homology to the presumed transposase of ISS1. An overlapping ORF of 174 bp in the same orientation was also present. A putative ORF in the opposite orientation to the transposase ORF, which has been shown in some iso-ISS1 elements, was not present in IS1297. IS1297 was shown to hybridize with other dairy Leuconostoc strains. This is the first sequence of an ISS1-like element from a genus other than Lactococcus; however, IS1297 has close similarity to the lactococcal iso-ISS1 elements, especially the iso-ISS1 element from the lactose plasmid, pTD1.

This paper reports the design of a Leuconostoc-specific oligonucleotide based on 16S rRNA sequence data. When this oligonucleotide was used in a polymerase chain reaction (PCR) in conjunction with an oligonucleotide to a conserved region of the 16S rRNA sequence, a Leuconostoc-specific PCR product of approximately 470 bp was produced. The use of a second oligonucleotide to a conserved region allowed the production of an approximately 350 bp product in all PCRs, acting as a positive control. The PCR procedure described was particularly useful for detecting the presence of Leuconostoc in mixed mesophilic starter cultures. The Leuconostoc-specific oligonucleotide was used also as a specific hybridization probe.

The 22163 bp genome of the lytic prolate-headed lactococcal phage c2 was fully sequenced. Mapping of restriction sites and RNA transcripts demonstrated the presence of early and late genes. Early and late promoters were identified. The early region contained 21 ORFs, with predicted protein products of 4.4-32.9 kDA, all reading right to left. Significant similarity was found between a putative protein encoded by an early region ORF and the erf (essential recombination function) gene product of Salmonella phage P22. The late genes for which a function has been identified, all of which read from left to right, included a possible holin gene, and genes encoding three major and six minor phage structural proteins. Analysis of the cohesive termini revealed complementary, non-symmetrical, 9-base single-stranded 3' extended DNAs. The exploitation of phage sequence data and analysis of phage genomes to find ways of inhibiting phage replication is discussed.

The cohesive termini of the DNA genome of the lactococcal bacteriophage c2 were directly sequenced and appeared to be complementary, non-symmetrical, 9-nucleotide single-stranded, 3' extended DNAs, with the following sequence: 5'-GTTAGGCTT-3' 3'-CAATCCGAA-5'. DNA located on either side of the cohesive ends was sequenced and several repeats and a region with the potential for a DNA bend were found. Previously sequenced cos regions of 13 other bacteriophages were also examined for similar sequence features. All of the bacteriophages from gram-positive hosts had 3' extended DNA termini, in contrast to the bacteriophages from gram-negative hosts, which had 5' extended DNA termini. All bacteriophages had a region of dyad symmetry close to the cohesive termini. A 7.3 kb DNA fragment of the c2 genome containing the cos sequences was cloned; transduction experiments demonstrated that these cloned sequences could act as a substrate for packaging enzymes of phage c2.

Intact bacteriophage of Lactococcus lactis were recovered from small volumes of lysate by centrifugation at 15,000 g without precipitation with polyethylene glycol and sodium chloride, or ultracentrifugation in a caesium chloride gradient. DNA was then extracted and purified by standard protocols. This DNA was readily digested with restriction endonucleases and used successfully in hybridization experiments.

This paper reports on the application of the ligase chain reaction (LCR) to the specific detection of variants of the nisin structural gene (nisinA and nisinZ) in nisin producing strains of Lactococcus lactis ssp lactis. The LCR assay was used to screen nisin producing strains to determine which form of the nisin structural gene they contained. This method of differentiating the nisin structural gene variants provides a useful alternative to the only other available genetic differentiation, that of sequencing the gene.

The use of insertion sequence probes for the analysis of fusants obtained following protoplast fusion is described. Hybridization of both total and plasmid DNA from parent and fusant strains with probes to IS904 and ISS1 showed that of the four protoplast fusions examined, three appeared to involve a rearrangement of genetic material while in the fourth the fusant appeared similar to one of the parental strains. This method of analysis provides more information about the changes induced by protoplast fusion than that obtained by monitoring the acquisition or loss of individual characteristics.

Transcription maps of the Lactococcus lactis subsp. lactis prolate phage c2 and small isometric phage sk1 were constructed. Early and late transcripts were demonstrated in phage c2. Early transcription was localized to within a 7.5-kb EcoRV fragment, and late transcription included the region which encodes the phage structural proteins and a lysin gene. Early, middle, and late transcripts were demonstrated in phage sk1. Transcription was confined to an 11.3-kb region defined by the three EcoRV restriction fragments of 6.2, 4.7, and 0.46 kb during the early part of the sk1 life cycle. Middle gene transcripts extended from the EcoRV site (defining the left-hand limit of early gene expression) through the cos site and included the 4.3-kb PvuII-cos fragment. Late transcription was detected over the remainder of the phage genome. These results indicated that gene expression was temporally regulated at the level of transcription in these two lactococcal phages and that two regions of time-dependent transcription exist in phage c2 and three in phage sk1.

Approximately 80% of the genome of the prolate-headed lactococcal bacteriophage c2 was cloned into shuttle vectors pSA3 and pFX3 in Escherichia coli and transferred to Lactococcus lactis. A 1.67-kilobase EcoRV fragment containing the gene for the phage lysin was identified and the position and orientation of the phage lysin gene in the physical map of the phage were determined. The phage lysin was expressed in E. coli and its sequence was determined and compared with the sequences of other bacteriophage lytic genes. The sequence was similar, but not identical, to that of the related lactococcal phage m13, having a number of silent substitutions and an apparent deletion that altered the carboxy terminus of the protein. Possible alternative translation initiation codons for the lysin gene and two possible alternative mechanisms for access of the lysin enzyme to the cell wall are discussed. An open reading frame upstream of the putative lysin gene was found to be 177 base pairs longer than that reported for phage m13. A codon usage table for the lysin genes of several phages as well as for reported gene sequences from L. lactis and lactococcal bacteriophages is presented.

A locus for an autosomal dominant form of spinocerebellar ataxia (SCA1) has been assigned to the short arm of chromosome 6 on the basis of linkage to the major histocompatibility system (HLA). In this study of a five-generation American black family, close linkage between the disease locus and both HLA and the coagulation factor XIIIA (F13A1) locus was excluded, and lod scores for all locations of the disease locus between HLA and F13A1 were less than -1.4. These results suggest that the locus causing spinocerebellar ataxia in this family is not in this region. However, the disease locus was found to be closely linked to a microsatellite polymorphism, D6S89, which is between HLA and F13A1. The maximum lod score for SCA1 and D6S89 is 4.90 at a recombination fraction of 0, both in males and in females. These data show that exclusion of close linkage to the HLA complex and F13A1 in a kindred with spinocerebellar ataxia does not rule out the possibility that the disease locus in that family is on 6p. Accordingly, all families segregating a dominantly inherited ataxia should be evaluated for linkage to D6S89, to determine whether the locus causing the disease is SCA1.

Pairs of unlinked genetic markers (blood cell antigens and enzymes and serum proteins) were tested for gametic equilibrium (GE) in data from 508 unrelated individuals from different regions of North America. A total of 24 markers were considered in the study. Only 14 of 262 pairs (5.3%) of markers deviated from GE at the 5% significance level and only 6 pairs (2.3%) remained in significant disequilibrium after accounting for genetic heterogeneity among regional groups. The particular combinations of alleles or one-locus genotypes that showed significant association were identified in case they might be replicated in future studies. On the basis of this study alone, however, there is no reason to suspect disequilibrium between the pairs of markers studied.

Segregation analysis has provided evidence suggesting the existence of a major gene for catechol-o-methyltransferase (COMT) activity in man. Five large families (4 Caucasian, 1 black), with a total of 1,189 individuals, were ascertained as part of a genetic study of blood pressure. Erythrocyte COMT activity and status at 25 polymorphic genetic marker loci were determined on more than 518 individuals in these pedigrees. Genetic linkage analysis of COMT with each of the 25 marker loci was performed in two ways: 1) using parameter estimates from segregation analysis of untransformed COMT activity, and 2) using parameter estimates from segregation analysis of the power transformation of the COMT activity that maximized the likelihood of the genetic hypothesis in each family. Tight and close linkage were excluded at 21 and 15 loci, respectively. A lod score of 1.27 at theta = 0.1 was found between the loci for COMT activity and phosphogluconate dehydrogenase (PGD). Transformation of the data had little effect on the outcome of the linkage analysis.

Robust methods were employed, using data from a single large pedigree, to screen serum apolipoprotein A1 and B levels, serum lipoprotein cholesterol levels, and ratios of serum lipoprotein cholesterol fractions to apolipoprotein A1 and B levels for genetic linkage to 31 polymorphic markers. Segregation analyses were performed for each of the apolipoprotein and lipoprotein cholesterol fractions to obtain estimates for use in applying likelihood methods of linkage analysis. Trait-marker combinations for which linkages were suggested from the robust methods were then reexamined for linkage using the likelihood (lod score) method. Results from the segregation analyses were consistent with major gene determination of apo B and HDL-C levels, the HDL-C to apo A1 ratio, the LDL-C to apo B ratio, and a measure of relative content of cholesterol in HDL-C and LDL-C. Linkage between haptoglobin and the HDL-C/apo A1 ratio was suggested, with a lod score of 1.72 at theta = 0.05.

Gram-negative, rod-shaped bacteria from the soil of white clover-ryegrass pastures were screened for their ability to nodulate white clover (Trifolium repens) cultivar Grasslands Huia and for DNA homology with genomic DNA from Rhizobium leguminosarum biovar trifolii ICMP2668 (NZP582). Of these strains, 3.2% were able to hybridize with strain ICMP2668 and nodulate white clover and approximately 19% hybridized but were unable to nodulate. Strains which nodulated but did not hybridize with strain ICMP2668 were not detected. DNA from R. leguminosarum biovar trifolii (strain PN165) cured of its symbiotic (Sym) plasmid and a specific nod probe were used to show that the relationship observed was usually due to chromosomal homology. Plasmid pPN1, a cointegrate of the broad-host-range plasmid R68.45 and a symbiotic plasmid pRtr514a, was transferred by conjugation to representative strains of nonnodulating, gram-negative, rod-shaped soil bacteria. Transconjugants which formed nodules were obtained from 6 of 18 (33%) strains whose DNA hybridized with that of PN165 and 1 of 9 (11%) strains containing DNA which did not hybridize with that of PN165. The presence and location of R68.45 and nod genes was confirmed in transconjugants from three of the strains which formed nodules. Similarly, a pLAFR1 cosmid containing nod genes from a derivative of R. leguminosarum biovar trifolii NZP514 formed nodules when transferred to soil bacteria.

A Rhizobium loti gene required for effective invasion of the host Lotus pedunculatus has been identified by transposon Tn5 mutagenesis. Cosmids that complemented a previously isolated mutation (239) at this invasion (inv) locus were identified by in planta complementation and used to construct a physical map of the gene region. The insertion site of Tn5 in PN239 was mapped to a 7.5-kb EcoRI fragment, which complemented the mutation when subcloned into pLAFR1. Further Tn5 mutagenesis of the 7.5-kb fragment was carried out in Escherichia coli using bacteriophage lambda 467, and the mutations homogenotized into R. loti NZP2037. Three additional Fix- mutations were isolated, and these were found to map adjacent to the position of the original mutation in strain PN239. All the other Tn5 insertions isolated in the 7.5-kb fragment gave a Fix+ phenotype on L. pedunculatus. Electron microscopic examination of the L. pedunculatus nodules induced by the isolated Fix- mutants showed that bacteria were either blocked in release from the infection threads or were unable to undergo normal bacteroid development. The inv locus as defined by the Tn5 insertions was sequenced, and a single open-reading frame (ORF) of 576 bp, corresponding to a polypeptide of 21.3 kDa, was identified. The position and orientation of this ORF were consistent with those of the isolated Tn5 Fix- insertions.

The kinetics of intracellular transport of the vesicular stomatitis virus (VSV) glycoprotein (G) and the Newcastle disease virus (NDV) hemagglutinin-neuraminidase (HN) glycoprotein in chicken embryo cells were compared. To assay for the appearance of pulse-labelled glycoprotein at the cell surface, an antibody-binding assay was developed which allowed the precipitation of only those molecules on the outside surfaces of infected cells. Using this assay, it was found that pulse-labelled VSV G protein appeared at the cell surface with a half-time of approximately 27 min, while pulse-labelled NDV HN glycoprotein reached the cell surface with a half-time of approximately 78 min. To determine the transit time of these glycoproteins to trans-Golgi membranes, the kinetics of the acquisition of endoglycosidase H resistance was analyzed. The half-time of the transit of the G protein to the trans-Golgi membranes was found to be approximately 13 min while that of the HN glycoprotein was found to be approximately 60 min. Since the G protein migrates to the trans-Golgi membranes with a half-time of 13 min, and the cell surface with a half-time of 27 min, the half-time for the transit between the trans-Golgi membrane and the plasma membrane must be approximately 14 min. In a similar analysis, the half-time for the transit of the HN glycoprotein from the trans-Golgi membrane to the plasma membrane must be approximately 18 min, a time not significantly different from that of the G protein. Thus the difference in the kinetics of the intracellular transport of these two glycoproteins resides primarily in the transit from the rough endoplasmic reticulum to the trans-Golgi membranes. These results argue against a non-selective mechanism for the transport of plasma membrane glycoproteins to the cell surface.

Friedreich ataxia (FA) is an autosomal recessive, neuro-degenerative disorder in which the pathogenetic mechanism remains unidentified despite extensive biochemical studies. Genetic-linkage studies provide an alternative approach to determining the basic defect. Linkage analysis between FA and 36 polymorphic-blood-group and protein markers has been carried out on three separate patient populations--16 families from the inbred Acadian population of Louisiana, 21 French-Canadian families from Quebec, and nine apparently unrelated British families--in an attempt to determine the chromosomal location of the disease mutation. Neither evidence of linkage to any of the markers investigated nor heterogeneity among the populations was found for any of the comparisons. The negative lod scores exclude the locus for FA from greater than 20% of the genome.

The fusion glycoprotein (Fo) of Newcastle disease virus is cleaved at an intracellular site (Nagai et al., Virology 69:523-538, 1976) into F1 and F2. This result was confirmed by comparing the transit time of the fusion protein to the cell surface with the time course of cleavage of Fo. The time required for cleavage of half of the pulse-labeled Fo protein is ca. 40 min faster than the half time of the transit of the fusion protein to the cell surface. To determine the cell compartment in which cleavage occurs, use was made of inhibitors which block glycoprotein migration at specific points and posttranslational modifications known to occur in specific cell membranes. Cleavage of Fo is inhibited by carbonyl cyanide m-chlorophenylhydrazone; thus, cleavage does not occur in the rough endoplasmic reticulum. Monensin blocks the incorporation of Newcastle disease virus glycoproteins into virions and blocks the cleavage of the fusion glycoprotein. However, Fo cannot be radioactively labeled with [3H] fucose, whereas F1 is readily labeled. These results argue that cleavage occurs in the trans Golgi membranes or in a cell compartment occupied by glycoproteins quite soon after their transit through the trans Golgi membranes. The implications of the results presented for the transit times of the fusion protein between subcellular organelles are discussed.

We tested for linkage between panic disorder and a battery of 29 genetic markers in 26 families. Linkage between panic disorder and 18 of the marker loci could be excluded at a recombination fraction of 0.00, nine at a recombination fraction of 0.05, and four at a recombination fraction of 0.10. The 18 loci are distributed over ten chromosomes. One locus was suggestive of linkage. The maximum lod score for alpha-haptoglobin was 2.27 at a recombination fraction of 0.0, representing odds in favor of linkage of 186.1. alpha-Haptoglobin has been mapped to chromosome 16q22. The results demonstrate that linkage studies of psychiatric disorders can yield informative results by identifying tentative linkages that merit further investigation and by excluding regions of the genome from future linkage searches.

A monoclonal antibody (2E2) produced against pectate lyase from Erwinia carotovora ssp. carotovora reacted with a 41- and a 44-kilodaltion protein on Western blots of concentrated Erwinia culture supernatants resolved by sodium dodecyl sulfate - polyacrylamide gel electrophoresis. It was unequivocally shown that monoclonal 2E2 reacted with an active form of pectate lyase by affinity purifying the antigen with the monoclonal. The affinity-purified antigen was enzymatically active and moved as a single protein band in a nonequilibrium isoelectric focusing gel. Monoclonal 2E2 reacted with the pectate lyases of a diverse range of E. carotovora ssp. carotovora, ssp. atroseptica, and ssp. betavasculorum strains, as well as with one of three strains of E. chrysanthemi. The electrophoretic mobility of the major protein (44 kilodaltons) that reacted with 2E2 was identical within a subspecies but differed among subspecies.

A large pedigree with high prevalence of heart disease is investigated to analyse the association between polymorphic blood markers and quantitative risk factors for cardiovascular disease. The analysis incorporates a familial correlation structure among the individuals in the pedigree and a generalized power transformation to induce approximate residual normality of the risk factors. A total of 380 marker/risk factor combinations are analysed, and at the normal 1% significance level, positive associations are found between the A antigen of the ABO locus and both serum total cholesterol and low-density lipoprotein cholesterol, and negative associations are found between the B antigen of the ABO locus and serum total cholesterol, and between the B allele of acid phosphatase (AP) locus and systolic blood pressure.

"Acadian ataxia" is a form of Friedreich ataxia found in individuals of Acadian ancestry. It was described by Barbeau (in Sobue I (ed): Spinocerebellar Degeneration; Tokyo: Univ. Tokyo Press, pp 121-142, 1980) as having a slower course of degeneration and less severe secondary symptoms than "classical" Friedreich ataxia. He suggested that these 2 forms of the disease may be distinct. The mutation causing "classical" Friedreich ataxia has recently been mapped to chromosome 9 through genetic linkage studies, and here we show that the locus causing Friedreich ataxia in Acadian families from southwestern Louisiana is tightly linked to the same DNA marker, D9S15. Thus, these 2 disorders, which may be differentiated clinically, are most probably due to mutation(s) at the same locus on chromosome 9.

The presence of a PGM1 null allele in a mother and her son was deduced from their inconsistent phenotypes. Quantitation studies were done to confirm the half-normal enzyme activity. Phenotype analysis of 29 additional genetic markers gave no indication of non-parentage, making non-maternity a very unlikely explanation for the discrepancy.