mtDNA single macrodeletions associated with myopathies: Absence of haplogroup-related increased risk

J. Inherit. Metab. Dis. 28 (2005) 769–778DOI: 10.1007/s10545-005-0023-z C© SSIEM and Springer

mtDNA single macrodeletions associated withmyopathies: Absence of haplogroup-relatedincreased riskA. GOIOS1,3,∗, C. NOGUEIRA2, C. PEREIRA2, L. VILARINHO2, A. AMORIM1,3

and L. PEREIRA1

1IPATIMUP (Instituto de Patologia e Imunologia Molecular da Universidade do Porto),Porto, Portugal; 2IGM (Instituto de Genetica Medica), Porto; 3Faculdade de Ciencias daUniversidade do Porto, Porto, Portugal

∗Correspondence: IPATIMUP, R. Dr. Roberto Frias, s/n, 4200-465 Porto, Portugal.E-mail: [email protected]

MS received 31.05.2004 Accepted 14.03.2005

Summary: As for any non-recombining genome, any mutation at mtDNA, if notrecurrent, appears on a particular haplotype background, allowing its detection by hap-logroup association studies. It has been shown that the propensity for occurrence ofsingle macrodeletions at a level beyond the pathological threshold is associated withsuper-haplogroup U/K. However, in this report, we present evidence for the absence ofpreferential haplogroup backgrounds for single macrodeletions. We have analysed howhaplogroup diagnostic polymorphisms could disrupt direct repeats usually flanking thedeleted segment, and we have concluded that for the Common Deletion, no such poly-morphisms are observed in humans, but they do occur in other primates. Furthermore,we also report five new single macrodeletions.

Rearrangements of human mtDNA molecules are responsible for a great variety of patho-logical states (progressive external ophthalmoplegia (PEO), Kearns–Sayre syndrome (KSS),Pearson syndrome (PS)) that result from the dysfunction of the respiratory chain and thefailure to generate cellular energy (Wallace et al 1999). They may consist of deletions,duplications or inversions of parts of the molecule, within a pair of breakpoints that arefrequently short, directly repeated sequences of up to 13 bp. The breakpoints vary, althoughthey usually lie between the two replication origins of the molecule, and therefore the regiondeleted rarely harbours the replication origins. The most frequent damage is the 4977 bpdeletion, usually referred to as the ‘Common Deletion’ (CD). The mechanism by whichthe rearrangement occurs is probably an illegitimate recombination, although replicationslippage has also been proposed (Kajander et al 2000).

The severity of the disease may differ depending on the proportion of mutant molecules(% heteroplasmy) and tissues affected. While in healthy individuals the level of deletedmolecules is usually very low, in affected tissues, such as muscle from patients with KSS,

769

770 Goios et al

they represent a high fraction of the mtDNA (Lightowlers et al 1997). Multiple deletionscan also be found in patients with this and other myopathies, but these have been related tomutations of the nuclear gene that encodes the polymerase gamma (Lamantea et al 2002;Wanrooij et al 2004). The symptoms of these syndromes are diverse and include ptosis,restricted eye movements and pigmentary retinopathy, as well as hearing loss, weakness,ataxia and cardiac and endocrine disorders (Crimi et al 2003; Torroni et al 2003).

Through the analysis of shared ancestral mtDNA polymorphisms, it is possible to defineethnically and geographically associated lineages (mtDNA haplogroups). It could be specu-lated that the incidence of deletions might be associated with some haplogroups or, at least,that there could be a higher probability of certain deletions in some haplogroups. Crimi andcolleagues (2003) reported a relationship between the A12308G polymorphism—a poly-morphism used to define the European mtDNA haplogroups U and K—and the clinicalfeatures of patients with the single mtDNA Common Deletion.

In this report, we present five novel mtDNA deletions, and test whether there is anyassociation between single macrodeletions and the haplogroup background.

MATERIAL AND METHODS

Patients presenting with mitochondrial cytopathies (MC) (n = 500) were submitted tomuscle biopsies, which were further analysed by (1) structural, (2) enzymatic (complexI, II, III, IV and II+III) and (3) molecular techniques. The molecular screening consistedof searching for the presence of the substitutions 3243, 3271 (associated with MELAS),the substitutions 8344, 8356 (MERRF), and the substitutions 8851, 8993, 9176 (NARP)by PCR-RFLP methodology, and for single or multiple mitochondrial DNA deletions bySouthern blot. To obtain a final map of deletions, we used a ‘primer shifting’ methodology,using reported oligonucleotide primers (Santorelli et al 1996). Single mtDNA deletionswere sequenced for characterization of the gaps. Percentage of heteroplasmy of the smallerfragments was estimated by densitometric scanning of the autoradiograms using a GS-700 imaging densitometer with multianalyst software. The main symptoms of the patientsharbouring deletions are indicated in Table 1.

We have further sequenced both hypervariable regions (HVRI and HVRII) of the mtDNAcontrol region in a sample of 25 patients harbouring mtDNA deletions in order to assign themto haplogroups. mtDNA was amplified using the primers L15997 (5′-CAC CAT TAG CACCCA AAG CT-3′) and H16401 (5′-TGA TTT CAC GGA GGA TGG TG-3′) for HVRI, andL48 (5′-CTC ACG GGA GCT CTC CAT GC-3′) and H408 (5′-CTG TTA AAA GTG CATACC GCC A-3′) for HVRII. The temperature profile was 95◦C for 10 s, 60◦C for 30 s and72◦C for 30 s for 35 cycles of amplification. The amplified samples were purified withMicrospin S-300 HR columns (Amersham Biosciences, Uppsala, Sweden), according tothe manufacturer’s specifications. Sequence reactions were carried out using the kit Big-DyeTerminator Cycle Sequencing Ready Reaction (AB Applied Biosystems, Foster City, CA,USA), with one of the above primers, in both forward and reverse directions. A protocolbased on MgCl2–ethanol precipitation was used for post-sequence reaction purification ofsamples, which were run in an automatic sequencer ABI 3100 (AB Applied Biosystems).

As control reference samples we used (a) 123 individuals from South Portugal (SP), (b)239 individuals from Central Portugal (CP), (c) 187 individuals from North Portugal (NP),

J. Inherit. Metab. Dis. 28 (2005)

mtDNA haplogroup background and single macrodeletions 771T

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772 Goios et al

Tab

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(Con

tinu

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mtDNA haplogroup background and single macrodeletions 773

as well as (d) the total database, summing up 549 individuals. These data are availableelsewhere (Pereira et al 2004).

Criteria for haplogroup classification of the sequences were as described by Richards andcolleagues (2000). We also checked the status at position 12308, since in some cases it isdifficult to distinguish haplogroup H from U considering only HVRI and HVRII diversity.Heterogeneity of haplogroup regional distributions was examined by chi-squared analysisusing the software DnaSP 4.0 (Rozas et al 2003).

RESULTS

Report of new deletions: Of the 500 patients presenting with myopathies, 33 harbourednine different single macrodeletions, five of which have not been reported previously. Themost frequently observed rearrangement was, as expected, the 4977 bp Common Deletion(17 cases, 52%).

The breakpoints of the five new deletions are presented in Table 2. All were locatedin the commonly deleted region (between the light-strand origin of replication, OL, andthe D-Loop; Figure 1). For the remaining deletions, there was a cluster of four deletionsin which the first breakpoint was situated between nucleotide position (np) 8421 and np8588, a region identified by Hou and Wei (1996) as exhibiting retarded mobility, and be-having like bent DNA structures. One other breakpoint was located at np 11036, in themtND4 gene. The second breakpoints of these deletions also seem to gather in two re-gions: three between np 12399 and np 13730, in the gene mtND5, and two between np15439 and np 15441, in the cytochrome b gene. They are all included in what Hou andWei (1996) described as a ‘hot region’ for the occurrence of sequences flanking large-scaledeletions.

Table 2 Junction, size and breakpoint locations for the deletions reported in this work and therepetitive motifs found in the flanking breakpoints

LocationDeletion of 1st/2ndno. Junction Size breakpoint Direct repeat Reference

1 8421–12399 3977 MTATP8 (8415) TCCTTAC (8421)MTND5 (12392) TCCTTAC (12398)

CD 8482–13460 4977 MTATP8 (8470) ACCTCCCTCACCA (8482) Mohri et al (1998)MTND5 (13447) ACCTCCCTCACCA (13459)

2 8536–15439 6902 MTATP6 –MTCYB –

3 8576–12984 4407 MTATP6 (8569) CTAGGCCT (8576)MTND5 (12976) CTAGGCCT (12983)

4 8588–13730 5142 MTATP6 (8583) CGCAG (8587)MTND5 (13725) CGCAG (13730)

5 11036–15441 4405 MTND4 –MTCYB –

CD, Common Deletion


774 Goios et al

Figure 1 Diagram representative of the detected deletions. The thin lines show the location ofthe deletion breakpoints on the mtDNA molecule. The location of deletions 6–9 has not yet beendetermined. The thick lines represent the size of the direct repeats existing in the breakpoints and arenot drawn to scale (for the Common Deletion the direct repeats are 13 bp long)

We also checked for repetitive motifs near the breakpoints of these newly reported dele-tions. Direct repeats (DR) were found in three of them (representing, with the CD, 67% ofthe total of deletions; Table 2): one was flanked by 5 bp repeats, another had 7 bp motifsand the third had 8 bp repeats.

Haplogroup assignment: The haplogroup was assigned for 25 of the patients on the basisof mtDNA polymorphisms present in HVRI and HVRII (Table 1). The median joiningnetwork for HVRI variation on these 25 patients (Figure 2) shows high haplogroup diversity,ranging from the typical Eurasian haplogroups H, K, T, U, W and X to the Sub-Saharan L andthe Eastern African M1. Moreover, individuals belonging to the same haplogroup presentdifferent haplotypes. The most frequent haplogroup found in the population of patientswith mtDNA deletions, and in particular with the CD, was the haplogroup H (15 out of 25individuals with deletions, and 9 out of 14 with the CD). This is not surprising, since this isalso the most common haplogroup in the population of Portuguese control individuals. Thesame applies for the sister haplogroups U/K, which appear as the second most frequent inour sample of patients (4 out of 25 individuals with deletions and 3 out of 14 with the CD)as is also observed in the control samples.

The haplogroup distributions for both the patient and control populations are summarizedin Table 3. We tested the differences between the samples through tests of independence,and concluded that there is no significant association between any of the most frequenthaplogroups and the presence of the CD. Additionally, when comparing the whole patientsample with mtDNA deletions with any of the control samples, no statistical differencewas observed (p ≤ 0.05), implying that there is no relationship between the haplogroupbackground and the development of mtDNA single macrodeletions.

Using a database composed of complete mtDNA sequences of 614 individuals worldwide,with all haplogroups represented (Herrnstadt et al 2002; Ingman et al 2000), we checkedfor polymorphism(s) in the direct repeats flanking the deletions, which could (a) contributeto increase the region of repetition or (b) disrupt the repetitive motif in certain haplogroupbackgrounds. This was found only for deletion 4, where there is a substitution at np 8584characteristic of the Asian sister haplogroups C and M8 that breaks the 5 bp DR in thesecond position. Apart from this, there were some sporadic substitutions, not typical of anyhaplogroup, that would disrupt the other DR (the majority, observed once): at positions



Table 3 Number of individuals belonging to haplogroupsH, U/K and other in the myopathy and control (NorthPortugal (NP), Central Portugal (CP) and South Portugal(SP)) samples

H U/K Other Total

Common Deletion 9 3 2 14Other deletions 6 1 4 11Total 15 4 6 25

Control NP 76 52 59 187Control CP 98 52 89 239Control SP 52 27 44 123Control Portugal 226 131 192 549

Figure 2 Network representation of the patients’ haplotypes. Numbers refer to the observed substi-tutions (minus 16000, transversions are indicated by the base) on the HVI sequence relative to theCambridge Reference Sequence. The areas of the circles are proportional to the frequency in thesample, the smallest circles being singletons


776 Goios et al

8417, 8419, 12396 and 12397, affecting the DR flanking the deletion 1; at 8470, 8472,8473, 8478, 8480 for the CD; and at 13725 for the deletion 4.

DISCUSSION

We describe five new single mtDNA deletions, all located in the commonly deleted region.Three of these deletions had direct repeats between 5 and 8 bp in the flanking regions. Theserepetitive motifs are ‘hotspots’, where rearrangements are more likely to occur, but otherfactors must be involved in the process to raise the frequency of molecules carrying a dele-tion to disease-causing levels. In fact, Kajander and colleagues (2000), studying differenttissues of healthy individuals, observed mtDNA deletions in all tissues, but the distributionof the deletions was curiously tissue specific. The trigger that unbalances the distributionof normal and deleted mitochondrial DNA molecules remains unknown. Chinnery andcolleagues (2004) propose a series of random genetic drift events during germline devel-opment, resulting in an affected zygote. According to these authors, very small amounts ofdeleted mtDNA present in the grandmother’s oocytes can be transmitted to the mother and,through successive bottlenecks, pathogenic levels of deleted molecules can be reached inonly two generations.

Crimi and colleagues (2003) reported a significantly higher frequency of the A12308Gpolymorphism in patients harbouring single macrodeletions. This polymorphism is charac-teristic of the sister haplogroups U and K, and when the authors subtyped the polymorphismA9052G, which they report determines the subhaplogroup K in combination with A12308G,they found that it was this haplogroup frequency that was significantly raised in individualswith macrodeletions, leading them to claim that ‘haplogroup K could be a risk factor formtDNA single macrodeletion’. It must be noted that the polymorphism that really sub-characterizes haplogroup K is G9055A (Finnila et al 2001; Herrnstadt et al 2002) and notA9052G. This position was reported in 1999 (Macaulay et al 1999) because RFLP analysiswas used for typing coding polymorphisms.

It is necessary to be extremely careful before making assumptions about pathogenic ef-fects of a certain polymorphism, as Crimi and colleagues (2003) recognize. In the caseof U/K haplogroups, besides the A12308G polymorphism, individuals belonging to hap-logroup U/K also share the polymorphisms A11467G (synonymous in ND4) and G12372A(synonymous in ND5), and the ones that are K share A3480G (synonymous in ND1),T9698C (synonymous in ATP6), A10550G (synonymous in ND4L), T11299C (synony-mous in ND4), C14167T (synonymous in ND6) and T14798C (replacement in CytB) be-sides G9055A (replacement in ATP6). An isolated site-specific approach in a molecule thatbehaves as a single locus is inappropriate.

In contrast to the results of Crimi and colleagues (2003), we did not find a preferentialhaplogroup background for mtDNA deletions associated with MC, even when only indi-viduals with the CD were considered. It is also important to note that the control populationused in Crimi’s report included patients who, for some reason, already had records in theDepartment of Neurology. The criteria for choosing the control population must be well es-tablished before making any conclusions. A presumed mtDNA haplogroup association witholigozoospermy was discounted when the comparison was made with microgeographicallymatched control samples (Pereira et al 2005).



One way in which haplogroup background could affect the propensity for deletionis the destruction/elongation of flanking repetitive motifs that are observed in the ma-jority of cases. We searched for this in the deletions reported here. The most impor-tant result corresponds to CD, owing to its high frequency. There was no haplogroupcharacteristic polymorphism destroying or elongating the 13 bp in the direct repeats flank-ing the CD, and these motifs seem quite conserved, only five mutations being observedin 5 out of 614 individuals (complete mtDNA sequences; Herrnstadt et al 2002; Ingmanet al 2000). In other primates, there are no pure DRs (first/second) in this region: there isone substitution in Pan troglodytes, ACCCCCCTCACCA/ACCTCCCTCACCA; two in Panpaniscus, ACCCCCCTCACCA/ACCTCCCTCATCA; two in Gorilla gorilla, ACCCCCCT-TACCA/ACCTCCCTCACCA; and three in Pongo pygmaeus, ACCCACCCCACCA/ACCT-CCCTCACCA. It would be worth searching for the presence of the CD in these species in or-der to determine whether an imperfect repeat motif is protective against thisdeletion.

It remains unclear how important these repetitive motifs dispersed throughout the mole-cule are. For instance, it is known that repetitive motifs (direct, inverted, mirror and com-plementary) are essential for three-dimensional organization of the tRNAs and rRNAs, andthey also may be essential for the secondary structure of the mtDNA molecule as it is not, asin the case of the nuclear genome, scaffolded in a highly sophisticated protein complex. Ifthis is the case, differences in mtDNA haplogroups might lead to differences in folding andto different patterns of direct repeats behaving as hot-spots for deletions. Studies involvinglarger datasets for humans, and a systematic in silico search across mammalian species,could allow testing of this hypothesis.

ACKNOWLEDGMENT

This work was partially supported by a PhD grant to AG (SFRH/BD/16518/2004) fromFundacao para a Ciencia e a Tecnologia and IPATIMUP by Programa Operacional Ciencia,Tecnologia e Inovacao (POCTI), Quadro Comunitario de Apoio III.

REFERENCES

Chinnery PF, DiMauro S, Shanske S, et al (2004) Risk of developing a mitochondrial DNA deletiondisorder. Lancet 364: 592–596.

Crimi M, Del Bo R, Galbiati S, et al (2003) Mitochondrial A12308G polymorphism affects clinicalfeatures in patients with single mtDNA macrodeletion. Eur J Hum Genet 11: 896–898.

Finnila S, Lehtonen MS, Majamaa K (2001) Phylogenetic network for European mtDNA. Am J HumGenet 68: 1475–1484.

Herrnstadt C, Elson JL, Fahy E, et al (2002) Reduced-median-network analysis of complete mito-chondrial DNA coding-region sequences for the major African, Asian, and European haplogroups.Am J Hum Genet 70: 1152–1171.

Hou JH, Wei YH (1996) The unusual structures of the hot-regions flanking large-scale deletions inhuman mitochondrial DNA. Biochem J 318: 1065–1070.

Ingman M, Kaessmann H, Paabo S, Gyllensten U (2000) Mitochondrial genome variation and theorigin of modern humans. Nature 408: 708–713.

Kajander OA, Rovio AT, Majamaa K, et al (2000) Human mtDNA sublimons resemble rearrangedmitochondrial genomes found in pathological states. Hum Mol Genet 9: 2821–2835.


778 Goios et al

Lamantea E, Tiranti V, Bordoni A, et al (2002) Mutations of mitochondrial DNA polymerase gammaAare a frequent cause of autosomal dominant or recessive progressive external ophthalmoplegia. AnnNeurol 52: 211–219.

Lightowlers RN, Chinnery PF, Turnbull DM, Howell N (1997) Mammalian mitochondrial genetics:heredity, heteroplasmy and disease. Trends Genet 13: 450–455.

Macaulay V, Richards M, Hickey E, et al (1999) The emerging tree of West Eurasian mtDNAs: asynthesis of control-region sequences and RFLPs. Am J Hum Genet 64: 232–249.

Mohri I, Taniike M, Fujimura H, et al (1998) A case of Kearns–Sayre syndrome showing a constantproportion of deleted mitochondrial DNA in blood cells during 6 years of follow-up. J Neurol Sci158: 106–109.

Pereira L, Cunha C, Amorim A (2004) Predicting sampling saturation of mtDNA haplotypes: anapplication to an enlarged Portuguese database. Int J Legal Med 118: 132–136.

Pereira L, Goncalves J, Goios A, Rocha T, Amorim A (2005) Human mtDNA haplogroups and reducedmale fertility: real association or hidden population substructuring. Int J Androl (in press).

Richards M, Macaulay V, Hickey E, et al (2000) Tracing European founder lineages in the NearEastern mtDNA pool. Am J Hum Genet 67: 1251–1276.

Rozas J, Sanchez-DelBarrio JC, Messeguer X, Rozas R (2003) DnaSP, DNA polymorphism analysesby the coalescent and other methods. Bioinformatics 19: 2496–2497.

Santorelli FM, Sciacco M, Tanji K, et al (1996) Multiple mitochondrial DNA deletions in sporadicinclusion body myositis: a study of 56 patients. Ann Neurol 39: 789–795.

Torroni A, Campos Y, Rengo C, et al (2003) Mitochondrial DNA haplogroups do not play a role inthe variable phenotypic presentation of the A3243G mutation. Am J Hum Genet 72: 1005–1012.

Wallace DC, Brown MD, Lott MT (1999) Mitochondrial DNA variation in human evolution anddisease. Gene 238: 211–230.

Wanrooij S, Luoma P, van Goethem G, van Broeckhoven C, Suomalainen A, Spelbrink JN (2004)Twinkle and POLG defects enhance age-dependent accumulation of mutations in the control regionof mtDNA. Nucleic Acids Res 32: 3053–3064.


mtDNA single macrodeletions associated with myopathies: Absence of haplogroup-related increased risk

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