Frequency of the mdr-1 C>T gene polymorphism in patients with COPD

BACKGROUND AND AIM:

The multi‐drug resistant‐1 (MDR‐1) gene is located on human chromosome 7 and encodes a glycosylated membrane protein that is a member of the ATP‐binding cassette transporters superfamily. The aim of the study was to reveal the role of the C3435T MDR‐1 gene polymorphism in chronic obstructive pulmonary disease.

METHOD:

DNA samples from 41 patients with chronic obstructive pulmonary disease and 50 healthy control participants were used to compare MDR‐1 gene profiles. Genotyping assays were performed using the StripAssay technique that is based on reverse‐hybridization.

RESULTS:

The T allele polymorphism in the MDR‐1 gene located at position 3435 in exon 26 was shown to correlate with chronic obstructive pulmonary disease.

CONCLUSION:

These preliminary results suggest that the T allele polymorphism of the MDR‐1 gene is associated with chronic obstructive pulmonary disease.     

Significant association of a M129V independent polymorphism in the 5' UTR of the PRNP gene with sporadic Creutzfeldt-Jakob disease in a large German case-control study

Background

A single nucleotide polymorphism (SNP) in the coding region of the prion protein gene (PRNP) at codon 129 has been repeatedly shown to be an associated factor to sporadic Creutzfeldt‐Jakob disease (sCJD), but additional major predisposing DNA variants for sCJD are still unknown. Several previous studies focused on the characterisation of polymorphisms in PRNP and the prion‐like doppel gene (PRND), generating contradictory results on relatively small sample sets. Thus, extensive studies are required for validation of the polymorphisms in PRNP and PRND.

Methods

We evaluated a set of nine SNPs of PRNP and one SNP of PRND in 593 German sCJD patients and 748 German healthy controls. Genotyping was performed using MALDI‐TOF mass spectrometry.

Results

In addition to PRNP 129, we detected a significant association between sCJD and allele frequencies of six further PRNP SNPs. No significant association of PRND T174M with sCJD was shown. We observed strong linkage disequilibrium within eight adjacent PRNP SNPs, including PRNP 129. However, the association of sCJD with PRNP 1368 and PRNP 34296 appeared to be independent on the genotype of PRNP 129. We additionally identified the most common haplotypes of PRNP to be over‐represented or under‐represented in our cohort of patients with sCJD.

Conclusion

Our study evaluated previous findings of the association of SNPs in the PRNP and PRND genes in the largest cohorts for association study in sCJD to date, and extends previous findings by defining for the first time the haplotypes associated with sCJD in a large population of the German CJD surveillance study.     

CRYM mutations cause deafness through thyroid hormone binding properties in the fibrocytes of the cochlea

Background

In a search for mutations of μ‐crystallin (CRYM), a taxion specific crystalline which is also known as an NADP regulated thyroid hormone binding protein, two mutations were found at the C‐terminus in patients with non‐syndromic deafness.

Objective

To investigate the mechanism of hearing loss caused by CRYM mutations

Methods

T3 binding activity of mutant μ‐crystallin was compared with that of wild‐type μ‐crystallin, because μ‐crystallin is known to be identical to T3 binding protein. To explore the sites within the cochlea where μ‐crystallin is functioning, its localisation in the mouse cochlea was investigated immunocytochemically using a specific antibody.

Results

One mutant was shown to have no binding capacity for T3, indicating that CRYM mutations cause auditory dysfunction through thyroid hormone binding properties. Immunocytochemical results indicated that μ‐crystallin was distributed within type II fibrocytes of the lateral wall, which are known to contain Na,K‐ATPase.

Conclusions

CRYM mutations may cause auditory dysfunction through thyroid hormone binding effects on the fibrocytes of the cochlea. μ‐Crystallin may be involved in the potassium ion recycling system together with Na,K‐ATPase. Future animal experiments will be necessary to confirm a causal relation between Na,K‐ATPase, T3, and deafness.     

The T/G 13915 variant upstream of the lactase gene (LCT) is the founder allele of lactase persistence in an urban Saudi population

Background

The prevalence of lactase persistence is high in Saudi Arabia.

Objective

To identify a DNA variant for the lactase persistence/non‐persistence trait in adult Arabs in Saudi Arabia.

Methods

We sequenced DNA from 432 anonymous neonatal blood donors from five different regions of Saudi Arabia to cover the 400 bp region surrounding the previously identified lactase persistence/non‐persistence variant C/T−13910 residing in intron 13 of the MCM6 gene.

Results

Two anonymous blood donors carried the C/T−13910 genotype. One variant, T/G −13915, residing 5 bp upstream of the C/T−13910 variant, was present in 332 of 432 (76.9%) of the neonatal samples, compatible with previous prevalence figures of lactase persistence in urban Saudi populations. Determination of disaccharidase activities in 25 intestinal biopsy samples showed a highly significant correlation between lactase activity and the T/G−13915 genotypes (p<0.001; Fisher exact test) as well as between the L:S ratio and the aforementioned genotypes (p<0.001; Fisher exact test).

Conclusion

The T/G−13915 variant is the founder mutation of lactase persistence in an urban Saudi population. The results obtained here have implications for genetic testing of adult‐type hypolactasia and to analysis of human evolution, the origin of cattle domestication and migrations of the populations in the Arabian peninsula.     

Penetrance of adrenocortical tumours associated with the germline TP53 R337H mutation

Background

An inherited germline P53 mutation has been identified in cases of childhood adrenocortical carcinoma (ACT), a neoplasm with a high incidence in southern Brazil. The penetrance of ACT in carriers of the point mutation, which encodes an arginine‐to‐histidine substitution at codon 337 of TP53 (R337H), has not been determined.

Objective

To investigate the penetrance of childhood ACT in carriers of the R337H TP53 mutation.

Methods

The family histories of 30 kindreds of 41 southern Brazilian children with ACT were obtained. A PCR based assay was used to detect this P53 mutation in a large number of relatives of children with ACT. In all, 927 individuals were tested for the mutation, 232 from the non‐carrier and 695 (including the 40 probands) from the carrier parental lines.

Results

40 children with ACT carried the TP53 R337H mutation; the remaining child with ACT was not tested. There was no evidence of Li‐Fraumeni syndrome in any of the kindreds; however, seven met the criteria for Li‐Fraumeni‐like syndrome. The carrier parental line was identified in each kindred. Of the 695 individuals tested in the carrier parental line, 240 (34.5%) were positive for the mutation, while none of the 232 individuals in the other parental line carried the mutation. The penetrance of ACT was 9.9% (95% confidence interval, 8.7% to 11.1%).

Conclusions

The TP53 R337H mutation dramatically increases predisposition to childhood ACT but not to other cancers, and explains the increased frequency of ACT observed in this geographic region.     

Cowden syndrome and Bannayan Riley Ruvalcaba syndrome represent one condition with variable expression and age-related penetrance: results of a clinical study of PTEN mutation carriers

Background

The most commonly reported phenotypes described in patients with PTEN mutations are Bannayan–Riley–Ruvalcaba syndrome (BRRS), with childhood onset, macrocephaly, lipomas and developmental delay, and Cowden Syndrome (CS), an adult‐onset condition recognised by mucocutaneous signs, with a risk of cancers, in particular those of the thyroid and breast. It has been suggested that BRRS and CS are the same condition, but the literature continues to separate them and seek a genotype–phenotype correlation.

Objective

To study the clinical features of patients with known PTEN mutations and observe any genotype–phenotype correlation.

Methods

In total, 42 people (25 probands and 17 non‐probands) from 26 families of all ages with PTEN mutations were recruited through the UK clinical genetics services. A full clinical history and examination were undertaken.

Results

We were unable to demonstrate a genotype–phenotype correlation. Furthermore, our findings in a 31‐year‐old woman with CS and an exon 1 deletion refutes previous reports that whole exon deletions are only found in patients with a BRRS phenotype.

Conclusion

Careful phenotyping gives further support for the suggestion that BRRS and CS are actually one condition, presenting variably at different ages, as in other tumour‐suppressor disorders such as neurofibromatosis type 1. This has important counselling implications, such as advice about cancer surveillance, for children diagnosed with BRRS.     

Lack of Association of the APOE ε4 Allele with the Risk of Obstructive Sleep Apnea: Meta-Analysis and Meta-Regression

Study Objectives:

Reports on the association of polymorphisms in the gene encoding apolipoprotein E (APOE)—a vital macromolecule in cholesterol metabolism—with obstructive sleep apnea (OSA) have provided conflicting results. Our objective was to meta-analytically synthesize the existing evidence for the association of the APOE ε4 allele with the risk of OSA.

Design:

Random effects meta-analysis and meta-regression

Setting:

Genetic epidemiological studies reporting the association of APOE ε4 allele with OSA susceptibility.

Patients or Participants:

Synthesis of APOE ε4 allele data from 6,508 subjects including 1,901 cases of OSA and 4,607 controls.

Interventions:

None

Measurements and Results:

Eight studies were included in the random effects meta-analysis; the summary effect size measured as odds ratio (OR) for association of the APOE ε4 allele with the risk of OSA was found to be 1.13 (95% confidence interval 0.86–1.47). There was a statistically significant heterogeneity (I² = 72%, P = 0.001) across study results that was not explained by the mean age, proportion of males, or the proportion possessing the APOE ε4 allele or when grouped based on the geographic location of the study.

Conclusions:

The hypothesis that the APOE ε4 allele may be causally associated with OSA cannot be supported on the basis of published literature.

Citation:

Thakre TP; Mamtani MR; Kulkarni H. Lack of association of the APOE ε4 allele with the risk of obstructive sleep apnea: meta-analysis and meta-regression. SLEEP 2009;32(11):1507-1511.     

A functional CD86 polymorphism associated with asthma and related allergic disorders

Background

Several studies have documented a substantial genetic component in the aetiology of allergic diseases and a number of atopy susceptibility loci have been suggested. One of these loci is 3q21, at which linkage to multiple atopy phenotypes has been reported. This region harbours the CD86 gene encoding the costimulatory B7.2 protein. The costimulatory system, consisting of receptor proteins, cytokines and associated factors, activates T cells and regulates the immune response upon allergen challenge.

Methods

We sequenced the CD86 gene in patients with atopy from 10 families that showed evidence of linkage to 3q21. Identified polymorphisms were analysed in a subsequent family‐based association study of two independent Danish samples, respectively comprising 135 and 100 trios of children with atopy and their parents. Functional analysis of the costimulatory effect on cytokine production was performed in an autologous cell‐based system based on cells expressing CD86 variants.

Results

Two polymorphisms were identified, encoding the amino acid changes Ile179Val and Ala304Thr, respectively. Significant associations were observed between the Ile179Val polymorphism and allergy phenotypes in both samples (eg, asthma, p = 4×10⁻³ in the two samples combined). The undertransmitted (protective) Val179 allele was found to induce higher production of both Th1 and Th2 cytokines than the overtransmitted (risk) Ile179 allele, suggesting a functional impact of the polymorphism.

Conclusion

The CD86 gene, and specifically the Ile179Val polymorphism, may be a novel aetiological factor in the development of asthma and related allergic disorders.     

Microarray based comparative genomic hybridization testing in deletion bearing patients with Angelman syndrome: genotype-phenotype correlations

Background

Angelman syndrome (AS) is a neurodevelopmental disorder characterised by severe mental retardation, dysmorphic features, ataxia, seizures, and typical behavioural characteristics, including a happy sociable disposition. AS is caused by maternal deficiency of UBE3A (E6 associated protein ubiquitin protein ligase 3A gene), located in an imprinted region on chromosome 15q11‐q13. Although there are four different molecular types of AS, deletions of the 15q11‐q13 region account for approximately 70% of the AS patients. These deletions are usually detected by fluorescence in situ hybridisation studies. The deletions can also be subclassified based on their size into class I and class II, with the former being larger and encompassing the latter.

Methods

We studied 22 patients with AS due to microdeletions using a microarray based comparative genomic hybridisation (array CGH) assay to define the deletions and analysed their phenotypic severity, especially expression of the autism phenotype, in order to establish clinical correlations.

Results

Overall, children with larger, class I deletions were significantly more likely to meet criteria for autism, had lower cognitive scores, and lower expressive language scores compared with children with smaller, class II deletions. Children with class I deletions also required more medications to control their seizures than did those in the class II group.

Conclusions

There are four known genes (NIPA1, NIPA2, CYFIP1, & GCP5) that are affected by class I but not class II deletions, thus raising the possibility of a role for these genes in autism as well as the development of expressive language skills.     

Novel NHLRC1 mutations and genotype-phenotype correlations in patients with Lafora's progressive myoclonic epilepsy

Background

Lafora''s progressive myoclonic epilepsy (Lafora''s disease) is an autosomal recessive neurodegenerative disorder characterised by the presence of polyglucosan intracellular inclusions called Lafora bodies. Mutations in two genes, EPM2A and NHLRC1, have been shown to cause the disease. A previous study showed mutations in the EPM2A gene in 14 Lafora''s disease families and excluded the involvement of this gene in five other families who were biopsy proven to have the disease.

Objective

To relate the genetic findings to the clinical course of the disease.

Methods

As part of an ongoing mutational study of the Lafora''s disease genes, five new families with the disease were recruited and the genetic analysis was extended to screen the entire coding region of the NHLRC1 gene. Genotype–phenotype correlations were carried out.

Results

Seven NHLRC1 mutations were identified, including five novel mutations (E91K, D195N, P218S, F216_D233del, and V359fs32), in eight families with Lafora''s disease. On relating the genetic findings to the clinical course of the disease it was shown that patients with NHLRC1 mutations had a slower rate of disease progression (p<0.0001) and thus appeared to live longer than those with EPM2A mutations. A simple DNA based test is described to detect the missense mutation C26S (c.76T→A) in the NHLRC1 gene, which is prevalent among French Canadians.

Conclusions

Patients with NHLRC1 mutations have a slower rate of disease progression than those with EPM2A mutations.     

Factor H autoantibodies in membranoproliferative glomerulonephritis

Factor H autoantibodies are found in ∼10% of aHUS patients. Most are associated with complete deficiency of factor H related proteins 1/3 and bind to the C terminal recognition domain. MPGN, like aHUS, is characterised by complement activation. In this study we, therefore, examined the hypothesis that factor H autoantibodies are associated with MPGN. We screened sera from 16 MPGN patients and 100 normal controls using ELISA and detected strongly positive IgG factor H autoantibodies in 2 patients. One patient had type II (DDD) MPGN (male aged 24 yrs) with C3NeF and the other type I (female aged 26 yrs) with no detectable C3NeF. We identified the binding site of the autoantibodies using small SCR domain fragments in the ELISA and showed that the autoantibodies in both patients bound predominately to the N terminal complement regulatory domain of factor H. We measured CFHR 1/3 copy number using MLPA and showed that both patients had 2 copies of CFHR1 and 3. Finally, we examined the functionality of detected factor H autoantibodies using purified patient IgG and observed increased haemolysis when purified IgG from both patients was added to normal human sera prior to incubation with rabbit red blood cells. Thus, in a cohort of MPGN patients we have found a high titre of functionally significant factor H autoantibodies in two patients with MPGN. Antibody depleting therapy may have a role in such patients and we suggest that screening for factor H autoantibodies should be undertaken in all patients with MPGN.     

The TNF-�� -308 polymorphism may affect the severity of Crohn's disease

OBJECTIVE:

The goal of this project was to analyze the association between Crohn''s disease, its clinical features, and the tumor necrosis factor alpha (TNF-α) -308 polymorphism.

METHODS:

This is a case-control and cross-sectional study that enrolled 91 patients with Crohn''s disease and 91 controls. Patients with Crohn''s disease were characterized according to the Montreal Classification, along with their clinical and surgical treatment history. Analysis of the TNF-α -308 polymorphism was performed using a commercial kit. A stratified analysis was applied using an OR (odds ratio) with a 95% confidence interval. The chi-square and Fisher''s exact tests were utilized for analysis of the association between the polymorphism and the clinical features of Crohn''s disease.

RESULTS:

The low producer predicted phenotype was present in 76.9% of Crohn''s disease cases and 75.8% of controls (OR 0.94 [0.45-1.97]). The TNF2 allele and the high producer predicted phenotype were more frequent among patients with Crohn''s disease penetrating behavior (p = 0.004). The TNF2 allele and the high producer predicted phenotype were also associated with a history of colectomy (p = 0.02), and the TNF2 allele was associated with small bowel resection (p = 0.03).

CONCLUSIONS:

The TNF-α -308 polymorphism appears to affect the severity of the disease. However, TNF-α -308 polymorphism does not appear to be important for the susceptibility in the development of Crohn''s disease.     

Tremor in X-linked recessive spinal and bulbar muscular atrophy (Kennedy's disease)

OBJECTIVE:

To study tremor in patients with X-linked recessive spinobulbar muscular atrophy or Kennedy''s disease.

METHODS:

Ten patients (from 7 families) with a genetic diagnosis of Kennedy''s disease were screened for the presence of tremor using a standardized clinical protocol and followed up at a neurology outpatient clinic. All index patients were genotyped and showed an expanded allele in the androgen receptor gene.

RESULTS:

Mean patient age was 37.6 years and mean number of CAG repeats 47 (44-53). Tremor was present in 8 (80%) patients and was predominantly postural hand tremor. Alcohol responsiveness was detected in 7 (88%) patients with tremor, who all responded well to treatment with a β-blocker (propranolol).

CONCLUSION:

Tremor is a common feature in patients with Kennedy''s disease and has characteristics similar to those of essential tremor.     

Genotype phenotype correlation of 30 patients with Smith-Magenis syndrome (SMS) using comparative genome hybridisation array: cleft palate in SMS is associated with larger deletions

Background

Smith‐Magenis syndrome (SMS) is rare (prevalence 1 in 25 000) and is associated with psychomotor delay, a particular behavioural pattern and congenital anomalies. SMS is often due to a chromosomal deletion of <4 Mb at the 17p11.2 locus, leading to haploinsufficiency of numerous genes. Mutations of one of these gemes, RAI1, seems to be responsible for the main features found with heterozygous 17p11.2 deletions.

Methods

We studied DNA from 30 patients with SMS using a 300 bp amplimers comparative genome hybridisation array encompassing 75 loci from a 22 Mb section from the short arm of chromosome 17.

Results

Three patients had large deletions (10%). Genotype–phenotype correlation showed that two of them had cleft palate, which was not found in any of the other patients with SMS (p<0.007, Fisher''s exact test). The smallest extra‐deleted region associated with cleft palate in SMS is 1.4 Mb, contains <16 genes and is located at 17p11.2‐17p12. Gene expression array data showed that the ubiquitin B precursor (UBB) is significantly expressed in the first branchial arch in the fourth and fifth weeks of human development.

Conclusion

These data support UBB as a good candidate gene for isolated cleft palate.     

Is the E133K allele of VG5Q associated with Klippel‐Trenaunay and other overgrowth syndromes?

Background

It has been reported that the activating mutation, E133K, in the angiogenic factor VG5Q (formally named AGGF1) causes Klippel‐Trenaunay Syndrome (KTS), a rare vascular disease associated with asymmetric overgrowth. This proposal followed from the observation that five out of 130 KTS patients were constitutionally heterozygous for VG5Q, E133K.

Objective

To explore the possibility that VG5Q, and specifically E133K, is implicated in other mosaic overgrowth syndromes.

Results

24 patients were analysed for this sequence change.One patient was constitutionally heterozygous for E133K. Analysis of both parents revealed that the patient''s mother, who was healthy, also carried E133K. An analysis of 275 healthy controls showed that 3.3% (9/275) of the population were carriers of E133K.

Conclusions

The findings bring into question the assertion that VG5Q, E133K is a mutation and that it causes KTS.     

Androgenetic/biparental mosaicism causes placental mesenchymal dysplasia

Background

Placental mesenchymal dysplasia (PMD) is a distinct syndrome of unknown aetiology that is associated with significant fetal morbidity and mortality. Intrauterine growth restriction is common, yet, paradoxically, many of the associated fetuses/newborns have been diagnosed with Beckwith‐Wiedemann syndrome (BWS).

Methods

We report two cases of PMD with high levels of androgenetic (complete paternal uniparental isodisomy) cells in the placenta and document, in one case, a likely androgenetic contribution to the fetus as well.

Results

The same haploid paternal complement found in the androgenetic cells was present in coexisting biparental cells, suggesting origin from a single fertilisation event.

Conclusions

Preferential allocation of the normal cells into the trophoblast explains the absence of trophoblast overgrowth, a key feature of this syndrome. Interestingly, the distribution of androgenetic cells appears to differ from that reported for artificially created androgenetic mouse chimeras. Androgenetic mosaicism for the first time provides an aetiology for PMD, and may be a novel mechanism for BWS and unexplained intrauterine growth restriction.     

Mutation in the epsilon subunit of the cytosolic chaperonin-containing t-complex peptide-1 (Cct5) gene causes autosomal recessive mutilating sensory neuropathy with spastic paraplegia

Background

Mutilating sensory neuropathy with spastic paraplegia is a very rare disease with both autosomal dominant and recessive modes of inheritance. We previously mapped the locus of the autosomal recessive form to a 25 cM interval between markers D5S2048 and D5S648 on chromosome 5p. In this candidate interval, the Cct5 gene encoding the epsilon subunit of the cytosolic chaperonin‐containing t‐complex peptide‐1 (CCT) was the most obvious candidate gene since mutation in the Cct4 gene encoding the CCT delta subunit has been reported to be associated with autosomal recessive mutilating sensory neuropathy in mutilated foot (mf) rat mutant.

Methods

A consanguineous Moroccan family with four patients displaying mutilating sensory neuropathy associated with spastic paraplegia was investigated. To identify the disease causing gene, the 11 coding exons of the Cct5 gene were screened for mutations by direct sequencing in all family members including the four patients, parents, and six at risk relatives.

Results

Sequence analysis of the Cct5 gene revealed a missense A492G mutation in exon 4 that results in the substitution of a highly conserved histidine for arginine amino acid 147. Interestingly, R147 was absent in 384 control matched chromosomes tested.

Conclusion

This is the first disease causing mutation that has been identified in the human CCT subunit genes; the mf rat mutant could serve as an animal model for studying these chaperonopathies.     

Total absence of the alpha2(I) chain of collagen type I causes a rare form of Ehlers-Danlos syndrome with hypermobility and propensity to cardiac valvular problems

Background

Heterozygous mutations in the COL1A1 or COL1A2 gene encoding the α1 and α2 chain of type I collagen generally cause either osteogenesis imperfecta or the arthrochalasis form of Ehlers‐Danlos syndrome (EDS). Homozygous or compound heterozygous COL1A2 mutations resulting in complete deficiency of the proα2(I) collagen chains are extremely rare and have been reported in only a few patients, albeit with variable phenotypic outcome.

Methods

The clinical features of the proband, a 6 year old boy, were recorded. Analysis of proα and α‐collagen chains was performed by SDS‐polyacrylamide gel electrophoresis using the Laemmli buffer system. Single stranded conformation polymorphism analysis of the proband''s DNA was also carried out.

Results

In this report we show that complete lack of proα2(I) collagen chains can present as a phenotype reminiscent of mild hypermobility EDS during childhood.

Conclusions

Biochemical analysis of collagens extracted from skin fibroblasts is a powerful tool to detect the subset of patients with complete absence of proα2(I) collagen chains, and in these patients, careful cardiac follow up with ultrasonography is highly recommended because of the risk for cardiac valvular problems in adulthood.