Evaluation of mtDNA common deletion in esophageal squamous cell carcinoma.

BACKGROUND: Mitochondrial defects are thought to play a role in cancer initiation and progression for a long time. Because of the absence of protective histones and an inefficiency in the DNA repair process, mitochondrial DNA is known to be prone to mutations. The deletion of 4977bp is one of the most common mutations in human cancers. This study aimed to investigate the relationship between 4977bp common deletion and Esophageal Squamous Cell Carcinoma Disease (SCC) to provide prognostic information. METHODS: By using a PCR protocol, this study identified the 4977bp deletion of mtDNA. A PCR method was used on tumor samples from 41 squamous cell carcinoma patients and blood samples from 50 healthy individuals to detect DNA. RESULTS: Among the 41 tumor samples (80.5%), 33 were found to have the 4977bp deletion, while none of the blood samples from healthy individuals contained it. CONCLUSIONS: It is shown that the deletion of 4977bp of mtDNA correlates significantly with SCC in this study. A 4977bp deletion could be used as an effective cancer screening indicator and biomarker for early diagnosis and prevention of cancer.

A novel deletion mutation in the ATP6V0A2 gene in an Iranian patient affected by autosomal recessive cutis laxa.

Cutis laxa (CL) can be caused by mutations in a number of genes. Cutis laxa with autosomal recessive inheritance due to mutations in several genes, including mutations in the ATP6V0A2 gene, causes autosomal recessive cutis laxa type 2A (ARCL2A). The ATP6V0A2 gene encodes the a2 subunit in the V-ATPases pump. The V-ATPases are located in the membrane of some organelles, including the Golgi or some vesicles, and act as ATP-dependent proton pumps to pH adjustment intracellular segments. Mutations in the ATP6V0A2 gene consist present in ARCL2A patients. We present the case of a 12-year-old girl who was referred to Rasad Laboratory (Tehran, Iran) at the age of 5 with a set of symptoms of congenital disorders. Her clinical phenotype contains distal symmetrical sensory and motor polyneuropathy, loose joints, large nasal roots, growth delay, and wrinkled skin. Also, there was a history of the parental marriage of consanguinity. A potentially pathogenic homozygous deletion mutation was detected in the ATP6V0A2 gene related to ARCL2A. This mutation has not been reported in the other patients with ARCL2A. A novel homozygous deletion mutation in ATP6V0A2 is supposed to be the reason for disease in our proband.

Analysis of TMIE gene mutations including the first large deletion of exon 1 with autosomal recessive non-syndromic deafness.

BACKGROUND: Transmembrane inner ear (TMIE) protein is an essential component of the mechanotransduction complex. In collaboration with other components, TMIE aids the maintenance and function of the sensory hair cells. Autosomal recessive deafness-6 (DFNB6) is caused by mutated TMIE, a gene in the high genetic heterogeneity spectrum of deafness. Hearing loss has a significant impact on the global economy and the quality of life of affected persons, their families, and society. Here, three unrelated families with TMIE variants are presented. All three cases were found while studying the genetic causes of an Iranian cohort of subjects with cochlear implants. METHODS: Whole exome sequencing was performed to find possible genetic etiology in probands of families after a comprehensive medical evaluation for hearing loss. Co-segregation analysis in probands and other family members was performed by Sanger sequencing. The variants were interpreted per the American College of Medical Genetics and Genomics guidelines. RESULTS: Three different variants associated with TMIE were confirmed as reasons for autosomal recessive non-syndromic deafness. The first novel ~ 10-kb deletion surrounding exon 1 of TMIE along with two previously reported variants co-segregated with families including a frameshift variant c.122_125dup (p.Pro43fs) and a missense variant c.250 C > T; p.(Arg84Trp) in exons 2, and 3, respectively. CONCLUSION: This study increases the mutational spectrum of the TMIE gene and highlights the importance of the large deletion of this gene as a reason for hearing loss. Moreover, an efficient and simple multiplex PCR assay was developed to determine the exact breakpoints of the TMIE deletion.

Association study between polymorphisms in MIA3, SELE, SMAD3 and CETP genes and coronary artery disease in an Iranian population.

BACKGROUND: Coronary artery disease (CAD) is the most common heart disease. Several studies have shown association between some polymorphism in different genes with CAD. Finding this association can be used in order to early diagnosis and prevention of CAD. METHOD: 101 CAD patients with ≥ 50% luminal stenosis of any coronary vessel as case group and 111 healthy individuals as control group were selected. the polymorphisms were evaluated by ARMS-PCR and RFLP-PCR methods. RESULT: The results of this study show that there is no significant association between rs17228212, rs17465637, and rs708272 and risk of CAD. But there is significant association between risk of CAD and rs5355 (p-value = 0.022) and rs3917406 (p-value = 0.006) in total cases, and rs5882 (p-value = 0.001) in male cases. CONCLUSIONS: Our findings revealed a significant interaction between CETP SNPs and CETP activity for affecting HDL-C levels. The SELE gene is a known cell adhesion molecule with a significant role in inflammation. Studies about possible linkage between SELE gene polymorphisms and the development of CAD are conflicting. We have found a significant association between polymorphisms of SELE gene and risk of CAD.

Cystinosis and two rare mutations in CTNS gene: two case reports.

BACKGROUND: Cystinosis is an autosomal recessive disorder characterized by an accumulation of the amino acid cystine in lysosomes throughout the body. Cystinosis is an inherited disease resulting from the failure of lysosomal cystine transport. The responsible gene, Cystinosin, Lysosomal Cystine Transporter (CTNS), encodes the lysosomal cystine carrier cystinosin. CASE PRESENTATION: In this case report, we reviewed the genetic basis of cystinosis and investigated two Iranian cases affected by cystinosis, one of which revealed a rare mutation in the CTNS gene. Two patients, 9-year-old (patient A) and 11-year-old (patient B) symptomatic Iranian females with renal insufficiency, were diagnosed with cystinosis on the basis of their clinical features and laboratory tests. After genetic counseling, blood samples were obtained from the patients and their parents. Genomic Deoxyribonucleic Acid (DNA) was extracted from whole blood, and mutation analysis was performed using polymerase chain reaction and sequencing methods for all exons of the CTNS gene. At least 148 different pathogenic and deleterious mutations in the CTNS gene have been reported to date. Owing to our patient's prominent clinical features of cystinosis, we carried out a targeted search for mutations in the CTNS gene. CONCLUSIONS: This led us to confirm the existence of a homozygous DNA variation c.257_258deletionCT (p.Ser86PhefsTer38) in exon 6 of the gene in patient A and another homozygous DNA variation, c.323delA (p.Q108RfsTer10), in the same exon in patient B. As expected, the mentioned mutation existed in both her parents in a heterozygous state. Variations c.257_258delCT and c.323delA reported in three Iranian patients in the CTNS gene are frameshifts, and truncating mutations that affect product function result in relatively mild symptoms of cystinosis. The present finding confirms previous research and proves the importance of the association of this gene rare mutations with cystinosis. Since reported mutations are rare, their previous reports in Iranian patients indicate the high frequency of these mutations in our region.

CAD gene and early infantile epileptic encephalopathy-50; three Iranian deceased patients and a novel mutation: case report.

BACKGROUND: Early infantile epileptic encephalopathy is a severe form of epilepsy that is genetically extremely heterogeneous and characterized by seizures or spasms at the beginning of infancy. Homozygous or compound heterozygous mutation in the CAD gene cause early infantile epileptic encephalopathy-50 (EIEE50). This case report describes the clinical and molecular features of three patients affected with early infantile epileptic encephalopathy. CASE PRESENTATION: In this report, we describe the clinical features of two deceased daughters and one recently deceased son affected with seizure, muscular hypotonia, and developmental delay. After genetic counseling, blood samples were obtained from the parents, and whole-exome sequencing was performed. Genomic DNA was extracted from whole blood, and mutation analysis was performed using PCR and sequencing methods for the CAD gene. Genetic analysis using the whole-exome sequencing method has detected a novel likely pathogenic mutation on CAD gene, c.2995G > A (p.Val999Met), in heterozygous states in asymptomatic parents and homozygous state in affected newborn son. This mutation has not been reported in the literature for its pathogenicity. CONCLUSIONS: The asymptomatic parents are carriers for the likely pathogenic variant in the CAD gene, and the recently deceased newborn son had the same mutation in a homozygous state. Given that, multiple lines of in silico computational analysis support the detrimental impact of the variant on the gene, and this variant is absent in population databases. Pathogenic mutations in the CAD gene are related to autosomal recessive EIEE50 with similar signs and symptoms to our patients. Ultimately, it is confirmed that this mutation is causative in our patients.

Novel mutation in TENM3 gene in an Iranian patient with colobomatous microphthalmia.

This investigation revealed a homozygous c.5069-1G>C variation in TENM3 gene although has not been reported for its pathogenicity and can be considered as a novel mutation. The present finding can be used for genetic diagnosis and detection of carriers in the family and other patients with similar disease manifestations.

Novel phenotype and genotype spectrum of NARS2 and literature review of previous mutations.

BACKGROUND: Mutations in NARS2 (MIM: 612803) are associated with combined oxidative phosphorylation deficiency 24 (COXPD24; MIM: 616239) that is a rare mitochondrial and a multisystem autosomal recessive disorder. AIMS: We aimed to detect the underlying genetic factors in two siblings with progressive ataxia, epilepsy, and severe-to-profound hearing impairment. METHODS: After doing medical assessments and pertinent tests (i.e., auditory brainstem responses, pure tone otoacoustic emission test, cardiac examinations, computed tomography, and electroencephalogram), because of the clinical and probable genetic heterogeneity, whole-exome sequencing was performed, and co-segregation analysis was confirmed by Sanger sequencing. Biological impacts of the novel variant were evaluated using sequence-to-function bioinformatics tools. RESULTS: A novel homozygous missense variant, NM_024678.6:c.545 T > A; p.(Ile182Lys), in exon 5 of NARS2 was identified in both patients and verified by Sanger sequencing. In silico analyses introduced this variant as pathogenic. Mitral valve prolapses with mild regurgitation, brachymetatarsia, severe hallux valgus, and clubbed fingers were reported as novel manifestations in association with NARS2 gene. By doing a literature review, we also underscored the high heterogeneity of disease phenotype. CONCLUSIONS: Herein, we report some novel phenotype and genotype features of two female patients in an Iranian consanguineous family with COXPD24, caused by a variant in NARS2-NM_024678.6: c.545 T > A; p.(Ile182Lys). Moreover, our data expanded the phenotype and genotype spectrum of NARS2-related disorder and confirmed an unpredictable nature of genotype-phenotype correlation in COXPD24.

Waardenburg syndrome type 2A in a large Iranian family with a novel MITF gene mutation.

BACKGROUND: The characteristics of Waardenburg syndrome (WS) as a scarce heritable disorder are sensorineural hearing loss and deficits of pigmentation in the skin, hair, and eye. Here, clinical features and detection of the mutation in the MITF gene of WS2 patients are reported in a sizable Iranian family. METHODS: A man aged 28-years represented with symptoms of mild unilateral hearing loss (right ear), complete heterochromia iridis, premature graying prior to 30 years of age, and synophrys. In this research, there was a sizable family in Iran comprising three generations with seven WS patients and two healthy members. Whole exome sequencing was applied for proband for the identification of the candidate genetic mutations associated with the disease. The detected mutation in proband and investigated family members was validated by PCR-Sanger sequencing. RESULTS: A novel heterozygous mutation, NM_198159.3:c.1026dup p.(Asn343Glufs*27), in exon 9 of the MITF gene co-segregated with WS2 in the affected family members. The variant was forecasted as a disease-causing variant by the Mutation Taster. According to the UniProt database, this variant has been located in basic helix-loop-helix (bHLH) domain of the protein with critical role in DNA binding. CONCLUSIONS: A frameshift was caused by a nucleotide insertion, c.1026dup, in exon 9 of the MITF gene. This mutation is able to induce an early termination, resulting in forming a truncated protein capable of affecting the normal function of the MITF protein. Helpful information is provided through an exactly described mutations involved in WS to clarify the molecular cause of clinical characteristics of WS and have a contribution to better genetic counseling of WS patients.

A novel mutation in the glutaryl-CoA dehydrogenase gene (GCDH) in an Iranian patient affected with Glutaric acidemia type 1.

Our findings revealed the mutation c.536T>C (p. Leu179Pro) in GCDH gene although has not been reported so far, but the in-silico analysis and clinical symptoms of the patient indicated that the mutation is pathogenic full stop. Also, it can be diagnosed and prevented in families affected by the disease.

Four mutations in MITF, SOX10 and PAX3 genes were identified as genetic causes of waardenburg syndrome in four unrelated Iranian patients: case report.

BACKGROUND: Waardenburg syndrome (WS) is a rare genetic disorder. The purpose of this study was to investigate clinical and molecular characteristics of WS in four probands from four different Iranian families. CASE PRESENTATION: The first patient was a 1-year-old symptomatic boy with congenital hearing loss and heterochromia iridis with a blue segment in his left iris. The second case was a 1.5-year-old symptomatic girl who manifested congenital profound hearing loss, brilliant blue eyes, and skin hypopigmentation on the abdominal region at birth time. The third patient was an 8-month-old symptomatic boy with developmental delay, mild atrophy, hypotonia, brilliant blue eyes, skin hypopigmentation on her hand and foot, Hirschsprung disease, and congenital profound hearing loss; the fourth patient was a 4-year-old symptomatic boy who showed dystopia canthorum, broad nasal root, synophrys, skin hypopigmentation on her hand and abdomen, brilliant blue eyes, and congenital profound hearing loss. Whole exome sequencing (WES) was used for each proband to identify the underlying genetic factor. Sanger sequencing was performed for validation of the identified mutations in probands and the available family members. A novel heterozygous frameshift mutation, c.996delT (p.K334Sfs*15), on exon 8 of the MITF gene was identified in the patient of the first family diagnosed with WS2A. Two novel de novo heterozygous mutations including a missense mutation, c.950G > A (p.R317K), on exon 8 of the MITF gene, and a frameshift mutation, c.684delC (p.E229Sfs*57), on the exon 3 of the SOX10 gene were detected in patients of the second and third families with WS2A and PCWH (Peripheral demyelinating neuropathy, Central dysmyelinating leukodystrophy, Waardenburg syndrome, Hirschsprung disease), respectively. A previously reported heterozygous frameshift mutation, c.1024_1040del AGCACGATTCCTTCCAA, (p.S342Pfs*62), on exon 7 of the PAX3 gene was identified in the patient of the fourth family with WS1. CONCLUSIONS: An exact description of the mutations responsible for WS provides useful information to explain the molecular cause of clinical features of WS and contributes to better genetic counseling of WS patients and their families.

Mutation detection and inhibitor risk in Iranian patients with Hemophilia A: Six novel mutations.

This investigation facilitates a better understanding of inhibitor development, the critical treatment morbidity in HA patients. Furthermore, six novel mutations are reported, which would expand the mutation spectrum of the F8 gene.

Novel homozygous variants in the TMC1 and CDH23 genes cause autosomal recessive nonsyndromic hearing loss.

BACKGROUND: Hereditary hearing loss (HL) is a heterogeneous and most common sensory neural disorder. At least, 76 genes have been reported in association with autosomal recessive nonsyndromic HL (ARNSHL). Herein, we subjected two patients with bilateral sensorineural HL in two distinct consanguineous Iranian families to figure out the underlying genetic factors. METHODS: Physical and sensorineural examinations were performed on the patients. Imaging also was applied to unveil any abnormalities in anatomical structures of the middle and inner ear. In order to decipher the possible genetic causes of the verified GJB2-negative samples, the probands were subjected to whole-exome sequencing and, subsequently, Sanger sequencing was applied for variant confirmation. RESULTS: Clinical examinations showed ARNSHL in the patients. After doing whole exome sequencing, two novel variants were identified that were co-segregating with HL that were absent in 100 ethnically matched controls. In the first family, a novel homozygous variant, NM_138691.2: c.530T>C; p.(lle177Thr), in TMC1 gene co-segregated with prelingual ARNSHL. In the second family, NM_022124.6: c.2334G>A; p.(Trp778*) was reported as a nonsense variant causing prelingual ARNSHL. CONCLUSION: These findings can, in turn, endorse how TMC1 and CDH23 screening is critical to detecting HL in Iranian patients. Identifying TMC1 and CDH23 pathogenic variants doubtlessly help in the detailed genotypic characterization of HL.

A novel frameshift mutation in the EDA gene in an Iranian patient affected by X-linked hypohidrotic ectodermal dysplasia.

PURPOSE: Ectodermal dysplasias are characterized by developmental abnormalities in ectodermal structures. Hypohidrotic ectodermal dysplasias (HED) are the most common subtype. They are most commonly inherited via X-linked recessive routes. We report on a novel ectodysplasin-A (EDA) mutation that is expected to be involved in pathogenesis of HED. METHODS: Hypohidrotic ectodermal dysplasia genes, including EDA, EDAR and EDARADD, were analyzed using next-generation sequencing (NGS). The detected mutation on the EDA gene was confirmed in the patient and his mother using Sanger sequencing. RESULTS: The patient presented with adontia, absence of gum development, hyperthermia and hypohidrosis. Our genetic analysis of the patient revealed a novel frameshift hemizygous mutation (c.898_924 + 8del35ins4CTTA) on the EDA gene. The patient's mother showed a mild HED phenotype. Direct sequencing of the EDA gene in the region where her son had the mutation showed the same mutation in a heterozygous state. CONCLUSION: We identified a novel frameshift mutation in the EDA gene in an Iranian patient affected by X-linked HED. The difference between our patient's symptoms and those recorded for some previous subjects may be due to the differences in the mutations involved.

Hereditary Ataxia with a Novel Mutation in the Senataxin Gene: A Case Report.

Hereditary ataxias (HA) are a group of inherited neurological disorders caused by changes in genes. At least 115 different mutations in the senataxin (SETX) gene causing ataxia have been identified. There are no reports of any SETX gene mutation among the Iranian population. Here we report on two cases with homozygous and heterozygous mutations in which one patient was affected by HA with oculomotor apraxia type 2, and the other was a carrier of the disorder. In 2016, the affected patient was referred to the Biogene Medical and Genetic Laboratory (Tehran, Iran) suffering from imbalance and tremor of both head and body. The coding regions of 18 genes, including the SETX gene, were screened. The target regions were captured using the NimbleGen chip followed by next-generation sequencing (NGS) technology on the Illumina Hiseq2500 platform. NGS, a DNA sequencing technology, has greatly increased the ability to identify new causes of ataxia; a useful tool for the prevention of primary manifestations and treatment of affected patients. In the present study, a novel mutation in the SETX gene has been identified.

Investigating the Association Between miR-608 rs4919510 and miR-149 rs2292832 with Colorectal Cancer in Iranian Population.

BACKGROUND: Single Nucleotide Polymorphisms (SNPs) in microRNA (miRNA) networks may serve as diagnostic and prognostic biomarkers of a variety of diseases such as cancer. Some studies have been performed to examine associations between miR-149 and miR-608 polymorphisms and susceptibility to colorectal cancer, but the results remain controversial and race-dependent. OBJECTIVE: The aim of our study was to investigate the association of miR-608 (rs4919510) and miR- 149 (rs2292832) with colorectal cancer and its clinical features in a sample of Iranian population. METHODS: This retrospective study was conducted on 76 CRC cases and 70 controls. Genotyping was performed using the polymerase chain reaction-restriction fragment length polymorphism (PCRRFLP) method. To confirm the RFLP process, 10% of the PCR products were validated by direct sequencing. RESULTS: Our findings showed significant correlation between adjusted data of rs2292832 with sex and age in TT genotype (OR= 5.148, 95% CI=1.081 ± 24.511, P=0.04). Distribution of rs4919510 polymorphism was not significantly different between controls and patients (CG, adjusted OR= 1.243, 95% CI=0.546 ± 2.831; P=0.604 and GG, adjusted OR= 0.249, 95% CI=0.063 ± 0.959; P=0.05). On the other hand, our results showed that a significant correlation was present between metastatic clinicopathological features and miR-608 (rs4919510) polymorphism (P=0.044). CONCLUSION: Our findings reveal that genotypes of rs2292832 and rs4919510 are not associated with risk of colorectal cancer in Iranian population. Moreover, the CC genotype of rs4919510 contributes to the metastatic features of the colorectal cancer.

Molecular analysis of patients with severe congenital factor X deficiency: First report from north and northwest of Iran.

Background Congenital FX deficiency is an extremely rare autosomal recessive disorder, mostly present in regions with a high rate of consanguinity, with an incidence of approximately 1:2,000,000 in the general population. The aim of this study was to evaluate the clinical manifestations and to provide a molecular analysis of 14 patients with homozygous factor X deficiency. Methods We evaluated the results of clinical and molecular characterization of 14 new cases (10 males, 4 females aged from 4 to 17 years) of FXD (FX activity <1%) in North and Northwest of Iran. FXD was diagnosed by clinical findings and routine laboratory tests. The PCR products of all the eight exons and their intron-exon boundaries were sequenced using DNA sequencer. Results Mean age of patients and mean age at diagnosis were 9 and 2.5 years, respectively. The molecular analysis revealed five different mutations, all of them were previously described. Molecular analysis showed five different homozygous and double heterozygous mutations including Arg-1Thr, Cys81Tyr, Gly78Asp, IVS1+3, and IVS2-3. Discussion The study of a large population of factor X patients from three institutions indicated that FXD was one of the most serious among rare bleeding disorders and that factor X gene mutation may be related to bleeding tendency in patients.

Mutation Detection in Activin A Receptor, Type I (ACVR1) Gene in Fibrodysplasia Ossificans Progressiva in An Iranian Family.

Fibrodysplasia Ossificans Progressiva (FOP, MIM 135100) is a rare genetic disease that is often inherited sporadically in an autosomal dominant pattern. The disease manifests in early life with malformed great toes and, its episodic and progressive bone formation in skeletal muscle after trauma is led to extra-articular ankylosis. In this study, a 17 year-old affected girl born to a father with chemical injury due to exposure to Mustard gas during the Iran-Iraq war, and her first degree relatives were examined to find the genetic cause of the disease. The mutation c.617G>A in the Activin A receptor, type I (ACVR1) gene was found in all previously reported patients with FOP. Therefore, peripheral blood samples were taken from the patient and her first-degree relatives. DNA was extracted and PCR amplification for ACVR1 was performed. The sequencing of ACVR1 showed the existence of the heterozygous c.617G>A mutation in the patient and the lack of it in her relatives. Normal result of genetic evaluation in relatives of the patient, ruled out the possibility of the mutation being inherited from parents. Therefore, the mutation causing disease in the child, whether is a new mutation with no relation to the father's exposure to chemical gas, or in case of somatic mutation due to exposure to chemical gas, the mutant cells were created in father's germ cells and were not detectable in his blood sample.

Osteopetrosis; a report of two Iranian patients with autosomal recessive inheritance pattern.

In the rare hereditary bone disorder of osteopetrosis, reduced bone resorption function leads to both the development of densely sclerotic fragile bones and progressive obliteration of the marrow spaces and cranial foramina. Marrow obliteration, typically associated with extramedullary hemopoiesis and hepatosplenomegaly, results in anemia and thrombocytopenia; and nerve entrapment accounts for progressive blindness and hearing loss. Severe infantile or malignant osteopetrosis is the worst type of the disease which has poor prognosis. In this study we report two cases of severe infantile or malignant type of the disease in an Iranian family. Our two patients were children of a family where the wife is a grandchild of the husband's aunt. The first patient had episodes of seizure and spastic in extremities 2 weeks after birth. Gradually, the patient showed upper and lower respiratory problems and horizontal nystagmus. X-Ray of hand and foot showed widening and increased bone density and physical examination showed hepatosplenomegallay and petechiae in extremities. The patient expired due to cardiopulmonary arrest. The second patient had also episodes of seizure 2 weeks after birth. Gradually, dissymmetry in eyes appeared and blindness was confirmed by ophthalmologist. Finally the patient expired because of severe pneumonia. Autosomal recessive osteopetrosis has been reported in most ethnic groups although it is more frequently seen in ethnic groups where consanguinity is common. We report for the first time two cases of severe infantile or malignant type of the disease in an Iranian family.

Detecting rare triple heteroplasmic substitutions in the mitochondrial DNA control region: a potential concern for forensic DNA studies.

OBJECTIVE: Mitochondrial DNA (mtDNA) is a useful tool for population studies, identification of humans and forensic DNA studies. The existence of several hundreds copies of mtDNA per cell permit its extraction from minute or degraded samples. In addition, the level of polymorphism in the hypervariable (HV) region is high enough to permit its use in human identity testing. However, the presence of several heteroplasmy might lead to ambiguous results. MATERIALS AND METHODS: This study was an experiental study. This study evaluated heteroplasmy in the HV region of mtDNA in blood samples of 30 Iranians who belonged to ten unrelated families from three sequential generations (grandmother, mother and daughter). RESULTS: There were no heteroplasmic substitutions in the HV1 region, but analysis of HV2 showed heteroplasmic substitutions in two out ten families. In the first family the grandmother showed heteroplasmy (T/C) in nucleotide positions 146 and 151, however it was not detected in the mother and daughter. In second family, a triple heteroplasmy (T/C) was detected in the daughter in nucleotide positions 146, 151 and 295, but these heteroplasmic substitutions were not obvious in the grandmother and mother. CONCLUSION: Heteroplasmy in mtDNA is not a rare phenomenon and probably exists in everyone, but a triple heteroplasmy in one family member is a novel finding. Our results demonstrate that one or two sequence differences between samples in mtDNA do not warrant exclusion. In our study, the average nucleotide difference between unrelated persons in the HV2 region was 2.8 nucleotides, whereas there was a triple heteroplasmy in one person which was not obvious in her family.