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Biomedical subjects

D E Bulman

Publications and source records attributed to D E Bulman.

At least 19 recordsLinked to original sources
PubMed2005

Neurofilament M gene in a French-Canadian population with Parkinson's disease.

BACKGROUND: Recently, a single base pair substitution (G1747A) mutation of the neurofilament M (NF-M) gene was reported in a French-Canadian patient with early onset Parkinson's disease (PD). Three unaffected siblings were found to be heterozygotes for the NF-M Gly336Ser mutation but, to date, no other affected PD individuals have been found with a similar mutation. No other individuals with Parkinson's disease and of similar ethnic background have been screened for this mutation. METHODS: We screened 102 French-Canadian patients with definite PD and 45 French-Canadian controls for this substitution in the NF-M gene using a PCR-restriction enzyme digestion method. RESULTS: None of the patients or controls carried this mutation. CONCLUSION: Our results would indicate that this mutation is not common even in a PD population of similar ethnic background and suggest this change represents a rare variant. However, these results do not exclude the possibility that other mutations in this gene could be present.

Aged↗
PubMed2003

Mutations in the epsilon-sarcoglycan gene found to be uncommon in seven myoclonus-dystonia families.

Myoclonus-dystonia syndrome (MDS) is a disorder for which the major cause appears to be mutations in the epsilon-sarcoglycan gene (SGCE). The authors have now performed mutation screening in 22 affected individuals from seven families with findings of typical MDS. A novel 5-bp deletion in exon 7 of the gene in one family and the previously reported R102X nonsense mutation in exon 3 in two other families were identified. Mutations in the SGCE gene were found in the minority of families screened in this series.

Adolescent↗
PubMed2003

Genetic mapping of a new Lafora progressive myoclonus epilepsy locus (EPM2B) on 6p22.

BACKGROUND: Lafora disease is a progressive myoclonus epilepsy with polyglucosan accumulations and a peculiar neurodegeneration with generalised organellar disintegration. It causes severe seizures, leading to dementia and eventually death in early adulthood. METHODS: One Lafora disease gene, EPM2A, has been identified on chromosome 6q24. Locus heterogeneity led us to search for a second gene using a genome wide linkage scan in French-Canadian families. RESULTS: We mapped a second Lafora disease locus, EPM2B, to a 2.2 Mb region at 6p22, a region known to code for several proteins, including kinesins. Kinesins are microtubule dependent motor proteins that are involved in transporting cellular components. In neurones, they play a major role in axonal and dendritic transport. CONCLUSION: Analysis of the present locus in other non-EPM2A families will reveal whether there is further locus heterogeneity. Identification of the disease gene will be of major importance towards our understanding of the pathogenesis of Lafora disease.

Chromosome Mapping↗
PubMed2002

A novel locus for inherited myoclonus-dystonia on 18p11.

OBJECTIVE: Inherited myoclonus-dystonia (IMD) is a new term for an autosomal dominant disorder characterized by myoclonus and dystonia. Recently, IMD was linked to a region on chromosome 11q23 with two different mutations identified in the D2 dopamine receptor gene and linked to chromosome 7q with five different loss-of-function mutations identified in the epsilon-sarcoglycan gene. METHODS: These two regions and genes were excluded in a large Canadian family with IMD in whom 13 individuals are affected. A 25-cM genome scan of this large family with 32 individuals was performed. RESULTS: Two-point linkage analysis revealed a maximum lod score of 3.5 (recombination fraction 0.00; affected only) for the microsatellite marker GATA185C06-18 and a multipoint lod score of 3.9 across the 18p11 region. Haplotype analysis demonstrates that all the affected individuals shared a common haplotype between markers D18S1132 and D18S843 that defines the disease gene within a span of 16.9 cM. CONCLUSIONS: These findings indicate that a novel IMD gene exists on chromosome 18p11.

Child↗
PubMed2002

Parkinson's genetics--creating exciting new insights.

Parkinson's disease is a complex disorder in which the genetic aspects are only just being realized. The underlying cause for the degeneration of dopaminergic substantia nigra neurons and the formation of Lewy bodies in Parkinson's disease is unknown. The identification of clear inherited forms of the disease has provided important clues as to how this complex process may be occurring. Mutations have now been identified in the alpha-synuclein (4q21.3-23), parkin (6q25.2-27), and ubiquitin carboxy terminal hydrolase-L1 (4p16.3) genes in families with Parkinson's disease. Four additional chromosomal locations; 2p13, 4p14-15, 1p35-36, and 12p11.2-q13.1 have been linked to Parkinson's disease families but no pathologic gene mutations have been identified to date. As additional Parkinson's disease loci are mapped and their genes identified we will continue to add to our understating of the critical biochemical pathways involved and be able to develop effective disease altering treatments.

Animals↗
PubMed2000

The human skeletal muscle Na channel mutation R669H associated with hypokalemic periodic paralysis enhances slow inactivation.

Missense mutations of the human skeletal muscle voltage-gated Na channel (hSkM1) underlie a variety of diseases, including hyperkalemic periodic paralysis (HyperPP), paramyotonia congenita, and potassium-aggravated myotonia. Another disorder of sarcolemmal excitability, hypokalemic periodic paralysis (HypoPP), which is usually caused by missense mutations of the S4 voltage sensors of the L-type Ca channel, was associated recently in one family with a mutation in the outermost arginine of the IIS4 voltage sensor (R669H) of hSkM1 (Bulman et al., 1999). Intriguingly, an arginine-to-histidine mutation at the homologous position in the L-type Ca(2+) channel (R528H) is a common cause of HypoPP. We have studied the gating properties of the hSkM1-R669H mutant Na channel experimentally in human embryonic kidney cells and found that it has no significant effects on activation or fast inactivation but does cause an enhancement of slow inactivation. R669H channels exhibit an approximately 10 mV hyperpolarized shift in the voltage dependence of slow inactivation and a twofold to fivefold prolongation of recovery after prolonged depolarization. In contrast, slow inactivation is often disrupted in HyperPP-associated Na channel mutants. These results demonstrate that, in R669H-associated HypoPP, enhanced slow inactivation does not preclude, and may contribute to, prolonged attacks of weakness and add support to previous evidence implicating the IIS4 voltage sensor in slow-inactivation gating.

Amino Acid Substitution↗
PubMed2000

Evidence favoring genetic heterogeneity for febrile convulsions.

PURPOSE: Two large Canadian kindreds appearing to segregate febrile convulsions as an autosomal dominant trait were evaluated for linkage to three known FC loci, as well as other epilepsy loci. METHODS: Members of the two families were genotyped with microsatellite markers linked to the previously identified febrile convulsion loci, FEB1, FEB2, and GEFS+, and we performed two-point linkage analyses by assuming an autosomal dominant mode of inheritance. RESULTS: We report the exclusion of the FC trait in our families to FEB1 on 8q13-21 and to a second febrile convulsion locus on 19p13. Furthermore, we also excluded the GEFS+ locus on 19q13.1 as the cause of febrile convulsions in both kindreds. Microsatellite markers linked to juvenile myoclonic epilepsy (EJM1), benign neonatal familial convulsions EBN1 and EBN2, autosomal dominant nocturnal frontal lobe epilepsy (ADNFLE), idiopathic generalized epilepsy (EGI), progressive myoclonic epilepsy of Unverricht-Lundborg (EPM1), and partial epilepsy with auditory features (EPT), were also excluded as potential loci linked to the FC trait in our families. CONCLUSIONS: These findings favor considerable genetic heterogeneity for febrile convulsions.

Age of Onset↗
PubMed2000

Clinical and radiological assessment of a family with mild brachydactyly type A1: the usefulness of metacarpophalangeal profiles.

The brachydactylies are a group of conditions in which various subtypes have been defined based upon the specific pattern of digital bones involved. Type A1 brachydactyly is principally characterised by maximal involvement of the middle phalanges. We report an extended family with a mild brachydactyly A1 which was, except for some short stature, not associated with any of the additional clinical findings reported in several published families. While all the hand bones tended to be small, the principal features of the affected members were shortened middle and distal phalanges, proximal 1st phalanges, and 5th metacarpals. The feet were similarly involved and tended to have a broad, slightly adducted forefoot. The two affected children showed multiple coned epiphyses. This paper provides a detailed description of the family including the radiographic signs and metacarpophalangeal profiles, which proved to be useful in distinguishing the mildly affected persons.

Adolescent↗
PubMed1999

A novel sodium channel mutation in a family with hypokalemic periodic paralysis.

OBJECTIVE: To identify the cause of hypokalemic periodic paralysis (HOKPP) in a family whose disease is not caused by a mutation in the dihydropyridine-sensitive (DHP) receptor alpha1-subunit gene (CACNA1S). BACKGROUND: Hypokalemic periodic paralysis is primarily caused by mutations within CACNA1S. Genetic heterogeneity for HOKPP has been reported, but no other locus has been identified. METHODS: Single-stranded conformational polymorphism (SSCP) analysis and PCR direct sequencing were used to screen the skeletal muscle alpha1-sodium channel gene (SCN4A) for a mutation in our family. RESULTS: SSCP analysis showed an abnormally migrating conformer in exon 12. Direct sequencing of the conformer showed a guanine to adenine transition at position 2006 in the cDNA sequence; this results in an amino acid substitution of a highly conserved arginine (Arg) to histidine (His) at position 669. This sequence alteration segregated only with the affected members of the kindred and was not found in a panel of 100 DNA samples from healthy controls. The amino acid substitution alters the outermost positive charge in the membrane spanning segment DII/S4, which is involved in voltage sensing. CONCLUSIONS: The first arginine in DII/S4 and in DIV/S4 within the skeletal muscle sodium channel and the L-type calcium channel genie CACNA1S appear to be critical for normal function. In all four cases, Arg to His mutations result in a disease phenotype. The identification of a mutation within the skeletal muscle sodium channel resulting in hypokalemic periodic paralysis represents a novel finding.

Adult↗
PubMed1999

An approach to ascertain probands with a non-traditional risk factor for carotid atherosclerosis.

In our previous studies of the determinants of carotid plaque area (CPA), we used a linear multiple regression model, which permitted us to control for the presence of known risk factors in order to reveal the contribution of putative new risk factors. We recognized that this approach could identify patients whose observed CPA was excessive when considering traditional risk factors. Subjects whose observed CPA markedly exceeded the expected CPA were easily identified because of their deviation from the regression line that was derived using all members of the study sample. We classified such subjects as having 'unexplained atherosclerosis' relative to the overall study sample when traditional risk factors were included as independent variables. We then examined the plasma homocyst(e)ine concentration in members of the subgroup with 'unexplained atherosclerosis'. We found a significantly higher mean plasma concentration of homocyst(e)ine in the subgroup with 'unexplained atherosclerosis', compared to rest of the study sample (20.4 +/- 4.3 vs. 13.2 +/- 3.2 mumol/l, P < 0.005). We also found that significantly more subjects with 'unexplained atherosclerosis' had plasma homocyst(e)ine concentrations in excess of 14 mumol/l compared to the rest of the study sample (52 vs. 33%, P < 0.002). We thus propose that systematic identification of subjects with 'unexplained atherosclerosis' relative to the rest of a well-characterized study sample might be a useful approach to identify subjects in whom there are newer, non-traditional determinants of predisposition to atherosclerosis.

Adult↗
PubMed1999

Childhood-onset primary open angle glaucoma in a Canadian kindred: clinical and molecular genetic features.

OBJECTIVE: To describe the clinical features and identify the molecular etiology of childhood-onset primary open angle glaucoma (POAG) in a Canadian kindred. METHODS: Members of a Canadian Caucasian family with POAG were examined and DNA obtained. Single-strand conformation polymorphism analysis was performed using reported primers from exon 3 of the myocilin gene. A single-stranded conformation polymorphism was characterized by polymerase chain reaction-based sequencing. RESULTS: Two affected half-sibs had onset of severe glaucoma at age 3 and 9. Their mother had lost vision in one eye from glaucoma by age 17. All three affected subjects had undergone bilateral glaucoma filtering surgery. Both fathers were unaffected. A single-stranded conformation polymorphism was identified in the mother and the two affected daughters and was absent in one father. A single base change from C-->T at nucleotide position 1109 was identified in the affected members of the family by direct sequencing. This mutation, which causes a nonconservative amino acid change (Pro370Leu), was not found on 192 normal chromosomes from Caucasian individuals. CONCLUSION: We report a Canadian family with childhood-onset, severe POAG due to a mutation in the myocilin gene.

Adult↗
PubMed1997

Phenotype variation and newcomers in ion channel disorders.

Ion channels are part of a large family of macromolecules whose functions include the control and maintenance of electrical potential across cell membranes, secretion and signal transduction. Close inspection of the physiological processes involved in channel function and the secondary structure of various ion channels has served as a basis for subdividing ion channels into a number of superfamilies. The voltage-gated ion channels are one of these superfamilies. Recent work has shown that mutations in various ion channel genes are responsible for a number of neuromuscular and neurological disorders. Correlation of the various mutations with the clinical phenotype is providing us with insight into the pathophysiology of these channel proteins. Interestingly, different mutations within the same gene may cause quite distinct clinical disorders, while mutations in different channel genes may result in very similar phenotypes (genetic heterogeneity). Examples of phenotypic variation and genetic heterogeneity are presented in the context of the periodic paralytic disorders of skeletal muscle, episodic ataxia, migraine, long QT syndrome and paroxysmal dyskinesia. Some of these disorders are known to be caused by mutations in ion channel genes, while in the episodic movement disorders, ion channel genes are considered excellent candidate genes.

Animals↗
PubMed1996

Familial hemiplegic migraine and episodic ataxia type-2 are caused by mutations in the Ca2+ channel gene CACNL1A4.

Genes for familial hemiplegic migraine (FHM) and episodic ataxia type-2 (EA-2) have been mapped to chromosome 19p13. We characterized a brain-specific P/Q-type Ca2+ channel alpha1-subunit gene, CACNL1A4, covering 300 kb with 47 exons. Sequencing of all exons and their surroundings revealed polymorphic variations, including a (CA)n-repeat (D19S1150), a (CAG)n-repeat in the 3'-UTR, and different types of deleterious mutations in FHM and EA-2. In FHM, we found four different missense mutations in conserved functional domains. One mutation has occurred on two different haplotypes in unrelated FHM families. In EA-2, we found two mutations disrupting the reading frame. Thus, FHM and EA-2 can be considered as allelic channelopathies. A similar etiology may be involved in common types of migraine.

Base Sequence↗
PubMed1996

A full genome search in multiple sclerosis.

The aetiology of multiple sclerosis (MS) is uncertain. There is strong circumstantial evidence to indicate it is an autoimmune complex trait. Risks for first degree relatives are increased some 20 fold over the general population. Twin studies have shown monozygotic concordance rates of 25-30% compared to 4% for dizygotic twins and siblings. Studies of adoptees and half sibs show that familial risk is determined by genes, but environmental factors strongly influence observed geographic differences. Studies of candidate genes have been largely unrewarding. We report a genome search using 257 microsatellite markers with average spacing of 15.2 cM in 100 sibling pairs (Table 1, data set 1 - DS1). A locus of lambda>3 was excluded from 88% of the genome. Five loci with maximum lod scores (MLS) of >1 were identified on chromosomes 2, 3, 5, 11 and X. Two additional data sets containing 44 (Table 1, DS2) and 78 sib pairs (Table 1, DS3) respectively, were used to further evaluate the HLA region on 6p21 and a locus on chromosome 5 with an MLS of 4.24. Markers within 6p21 gave MLS of 0.65 (non-significant, NS). However, D6S461, just outside the HLA region, showed significant evidence for linkage disequilibrium by the transmission disequilibrium test (TDT), in all three data sets (for DS1 chi2 = 10.8, adjusted P < 0.01)(DS2 and DS3 chi2 = 10.9, P < 0.0005), suggesting a modest susceptibility locus in this region. On chromosome 5p results from all three data sets (222 sib pairs) yielded a multipoint MLS of 1.6. The results support genetic epidemiological evidence that several genes interact epistatically to determine heritable susceptibility.

Chromosome Mapping↗
PubMed1996

X linked spondyloepiphyseal dysplasia: a clinical, radiological, and molecular study of a large kindred.

X linked spondyloepiphyseal dysplasia (SEDT) is a rare disorder characterised by disproportionate short stature and degenerative changes in the spine and hips. We report a large kindred with 11 affected males and 17 obligate carrier females. We examined clinically and radiographically the seven living affected males and obtained detailed historical information on the four dead. The natural history was characterised by normal growth until late childhood. Decreased growth velocity was the earliest detectable abnormality. In adulthood, four subjects required hip replacements but disability was minimal. Clinical examinations showed a characteristic habitus with short stature (> 2 SD below the mean) and a decreased upper segment to lower segment ratio (> 1 SD below the mean) in all affected subjects. Also noted were scoliosis (6/7), and decreased range of hip rotation (6/7), and decreased range of movement of the lumbar spine (4/7). Radiographic evaluations were available on nine subjects. Radiographic changes were evident in two patients in childhood; findings in adulthood included narrow disc spaces (8/9), platyspondyly (7/9), the characteristic central and posterior hump of the vertebral bodies (6/9), bony spurs (7/ 8), and pelvic abnormalities (7/9). We also systematically evaluated eight obligate carrier females. They could not be distinguished from the general population on clinical and radiographic findings. Linkage analysis showed significant linkage with markers on Xp22, as previously reported. A recombinant event between DXS43 and DXS207 places the locus distal to DXS43.

Adolescent↗