Exosomes derived from synovial fibroblasts from patients with rheumatoid arthritis promote macrophage migration that can be suppressed by miR-124-3p.

Objectives: Exosomes are potent vehicles for intercellular communication. Rheumatoid arthritis (RA) is a chronic systemic disease of unknown etiology. Local administration of miR-124 precursor to rats with adjuvant-induced arthritis suppresses systemic arthritis and bone destruction. Thus, exosomes may be involved in this disease. We aimed to determine the role of exosomes in the pathology of RA. Methods: Fibroblast-like synoviocytes (FLS) were collected from patients with RA and osteoarthritis (OA). miR-124-3p mimic was transfected into the RA FLS (RA miR-124 FLS). Exosomes were collected from the culture medium by ultracentrifugation. Macrophages were produced from THP-1 cells. MicroRNAs in the exosomes were analyzed using real-time PCR. Proteomics analysis was performed using nanoscale liquid chromatography-tandem mass spectrometry. Macrophage migration was evaluated using a Transwell migration assay. SiRNA was used to knockdown proteins of interest. Results: MicroRNAs in the RA FLS, RA miR-124 FLS, and OA FLS exosomes were similar. Proteomics analysis revealed that pentraxin 3 (PTX3) levels were higher in RA FLS exosomes than in RA miR-124 FLS and OA FLS exosomes, and proteasome 20S subunit beta 5 (PSMB5) levels were lower in RA FLS exosomes than in RA miR-124 FLS and OA FLS exosomes. The RA FLS exosomes promoted and the RA miR-124 FLS exosomes suppressed macrophage migration. PTX3-silenced RA FLS exosomes suppressed and PSMB5-silenced OA FLS exosomes promoted macrophage migration. Conclusions: RA FLS exosomes promote macrophage migration via PTX3 and PSMB5, and miR-124-3p suppresses this migration.

Comparison of 17 serological treponemal and nontreponemal assays for syphilis: A retrospective cohort study.

Objectives: Rapid plasma reagin (RPR) and Treponema pallidum (TP) antibody test kits are often used to diagnose syphilis, although the relationship between their measured values is unclear. We aimed to reveal the relevance of these kits' results. Design and methods: In all, 143 sera from 110 patients were tested using 12 TP kits and 5 RPR kits and the results compared. Results: The specificity and sensitivity of RPR kits were 81-96% and 95-100%, respectively. The correlation coefficients (0.849-0.934) considerably differed between the manual RPR card test and latex agglutination (LA) assay kits. The following sensitivities were obtained: 82-91% for TP fluorescent treponemal antibody absorption assay (FTA-ABS), TP hemagglutination assay (HA), and TP particle agglutination assay (PA); 94-95% for TP LAs; and 92-100% for chemiluminescent immunoassay (CLIA), chemiluminescent enzyme immunoassay (CLEIA), and immunochromatography assay (IC). Correlation coefficients between TP kits were 0.753-0.974, and the measured values varied. Changes in RPR and quantifiable TP kits were the same for patients with reinfected syphilis and with syphilis under treatment. Conclusions: RPR tests had lower specificity than TP antibody tests. RPR card test and RPR LAs had similar specificity and sensitivity, but their measured values were different. RPR should be measured using automatic RPR LA without setting the upper limit of the reported value. RPR LA should also be standardized. The sensitivity of TP antibody was better in CLIA, CLEIA, and IC than in FTA-ABS, HA, PA, and LA. Therefore, TP antibody kits should be standardized and quantified.

Identification of plexin D1 on circulating extracellular vesicles as a potential biomarker of polymyositis and dermatomyositis.

OBJECTIVES: We aimed to identify disease-specific surface proteins on extracellular vesicles (EVs) as novel serum biomarkers of PM/DM. METHODS: We performed liquid chromatography-tandem mass spectrometry (LC/MS) on purified EVs from sera of 10 PM/DM patients, 23 patients with other autoimmune diseases and 10 healthy controls (HCs). We identified membrane proteins preferentially present in EVs of PM/DM patients by bioinformatics and biostatistical analyses. We developed an EV sandwich ELISA for directly detecting serum EVs expressing disease-specific membrane proteins and evaluated their clinical utility using sera from 54 PM/DM, 24 RA, 20 SLE, 13 SSc and 25 Duchenne and Becker types of muscular dystrophy (DMD/BMD) patients and 36 HCs. RESULTS: LC/MS analysis identified 1220 proteins in serum EVs. Of these, plexin D1 was enriched in those from PM/DM patients relative to HCs or patients without PM/DM. Using a specific EV sandwich ELISA, we found that levels of plexin D1+ EVs in serum were significantly greater in PM/DM patients than in HCs or RA, SLE or DMD/BMD patients. Serum levels of plexin D1+ EVs were greater in those PM/DM patients with muscle pain or weakness. Serum levels of plexin D1+ EVs were significantly correlated with levels of aldolase (rs = 0.481), white blood cells (rs = 0.381), neutrophils (rs = 0.450) and platelets (rs = 0.408) in PM/DM patients. Finally, serum levels of plexin D1+ EVs decreased significantly in patients with PM/DM in clinical remission after treatment. CONCLUSION: We identified levels of circulating plexin D1+ EVs as a novel serum biomarker for PM/DM.

Genetic Analysis of UGT1A1 Polymorphisms Using Preserved Dried Umbilical Cord for Assessing the Potential of Neonatal Jaundice as a Risk Factor for Autism Spectrum Disorder in Children.

Neonatal jaundice has been suggested as a perinatal risk factor for autism spectrum disorder (ASD). We examined UGT1A1 polymorphisms to assess the potential of neonatal jaundice as a risk factor for ASD in children by using DNA extracted from preserved umbilical cord. In total, 79 children with ASD were genotyped for UGT1A1*28 (c.-41-40dup), UGT1A1*6 (c.211 G > A), and UGT1A1*27 (c.686 C > A). The allele frequency of UGT1A1*6 (OR = 1.34, p = 0.26) and UGT1A1*28 (OR = 0.80, p = 0.54) and the prevalence of UGT1A1*28/*6 diplotypes did not differ significantly from those in the control population. No UGT1A1*27 allele was detected in the subjects. ASD symptom assessment scores were not associated with UGT1A1*28/*6/*27 genotypes or UGT1A1*28/*6 diplotypes. These results suggest that neonatal jaundice is not significantly associated with ASD.

Lymphoplasmacytic lymphoma in a patient with Birt-Hogg-Dubé syndrome.

Birt-Hogg-Dubé (BHD) syndrome is an autosomal dominant disease characterized by benign skin hamartomas, pulmonary cysts leading to spontaneous pneumothorax, and an increased risk of renal cancer. BHD syndrome is caused by germline mutations in the folliculin (FLCN) gene, a putative tumor suppressor, which result in loss of function of the folliculin protein and may cause cancer predisposition. In a 45-year-old woman with anemia, lymphadenopathy, and a history of recurrent spontaneous pneumothorax, 18F-FDG PET/CT detected diffuse and slight 18F-FDG accumulation in the bone marrow, enlarged spleen, and systemic multiple enlarged lymph nodes. Genetic examination identified a germline nonsense mutation [c.998C > G (p.Ser333*)] on exon 9 of FLCN. Pathological examination of the lymph node revealed a diffuse neoplastic proliferation of plasmacytoid lymphocytes. The neoplastic lymphoid cells were positive for CD20, CD138, and light chain kappa as per immunohistochemistry and mRNA in situ hybridization, and a MYD88 gene mutation [c.755T > C (p.L252P)] was identified. Accordingly, she was diagnosed with lymphoplasmacytic lymphoma concomitant with BHD syndrome. To the best of our knowledge, this is the first report describing the development of hematological malignancy in a patient with BHD syndrome. The FLCN mutation might contribute lymphomagenesis as an additional mutation cooperating with the MYD88 mutation.

Detection of a novel CBFB-MYH11 fusion transcript in acute myeloid leukemia M1 with inv(16)(p13q22).

Acute myeloid leukemia (AML) with an inv(16)(p13q22) or t(16;16)(p13;q22) chromosomal abnormality represents one of the most common subtypes of de novo cases. These chromosomal rearrangements result in multiple CBFB-MYH11 fusion transcripts, with type-A being the most frequent. We here describe a unique case of de novo AML-M1, with inv(16)(p13q22), leading to an unusual CBFB-MYH11 fusion transcript, and der(7)t(7;11)(q31;q21). The fusion transcript involves a CBFB exon 5 with a breakpoint at nucleotide 754, an insertion of a 13-bp sequence of CBFB intron 5 at the fusion point, and the MYH11 exon 27 with a breakpoint at nucleotide 3464. To our knowledge, this CBFB-MYH11 fusion transcript has never been reported previously. The clinical characteristics of the present case are in line with previous reports suggesting that rare CBFB-MYH11 fusion transcripts lead to aberrant characteristics such as an atypical cytomorphology and additional cytogenetic abnormalities.

Diagnostic Value of Cytomegalovirus IgM Antibodies at Birth in PCR-Confirmed Congenital Cytomegalovirus Infection.

Although cytomegalovirus (CMV) DNA detection in urine is the standard method for diagnosing congenital cytomegalovirus infection (CCMVI), polymerase chain reaction (PCR) is not comprehensively available. Currently, the efficacy of CMV-specific IgM (CMV-IgM) and CMV-specific IgG (CMV-IgG) detection remains unclear. To determine the sensitivity and specificity of CMV-specific antibodies at birth, we investigated CMV-IgM and CMV-IgG titers in CCMVI cases and non-CCMVI controls, with confirmed diagnoses by urine quantitative real-time PCR within 3 weeks after birth. We included 174 infants with suspected CCMVI in whom serological testing was performed within the first 2 weeks after birth during 2012-2018. We classified the participants into a CCMVI group (n = 32) and non-CCMVI group (n = 142) based on their urine PCR results. The CMV-IgM-positive rate was 27/32 (84.4%) in the CCMVI group, compared with 1/142 (0.7%) in the non-CCMVI group (p < 0.0001). The positive CMV-IgG rates were 32/32 (100%) in the CCMVI group and 141/142 (99.3%) in the non-CCMVI group. The positive predictive value for CMV-IgM was high at 96.4% (27/28). This value may be sufficient for clinical use, especially in settings with limited resources where PCR is unavailable. However, CCMVI screening by CMV-IgM alone appears insufficient because of the considerable number of false-negative cases.

Prediction of poor neurological development in patients with symptomatic congenital cytomegalovirus diseases after oral valganciclovir treatment.

OBJECTIVE: This study aimed to evaluate the neurodevelopmental outcomes of infants with symptomatic congenital cytomegalovirus (SCCMV) disease after antiviral treatment and investigate the symptoms at birth associated with a developmental quotient (DQ) < 70. METHODS: In this prospective study conducted from 2009 to 2018, infants with SCCMV disease who received oral valganciclovir (VGCV; 32 mg/kg/day) for 6 weeks (November 2009 to June 2015) or 6 months (July 2015 to March 2018) were evaluated for their neurodevelopmental outcomes at around 18 months of corrected age. Sequelae were categorized as follows: no impairment with a DQ ≥ 80 and no hearing dysfunction; mild sequelae including unilateral hearing dysfunction or a DQ of 70-79; and severe sequelae with a DQ < 70, bilateral hearing dysfunction requiring hearing aids, blindness or epilepsy requiring anti-epileptic drugs. DQ was assessed using the Kyoto Scale of Psychological Development. Symptoms at birth associated with a DQ < 70 were determined using univariate and receiver operating characteristic curve analyses. RESULTS: Of the 24 treated infants, 21 reached > 18 months of corrected age. Six (29%) were no impairment, 4 (19%) had mild sequelae, and 11 (52%) developed severe sequelae. The symptoms at birth associated with a DQ < 70 were microcephaly and/or small for gestational age. CONCLUSION: In our cohort of infants with SCCMV disease after VGCV treatment, the incidence of severe sequelae at 18 months of corrected age was around 50%. When microcephaly and/or small for gestational age are seen at birth, a low DQ may appear even after oral VGCV treatment.

Efficacy of Valganciclovir Treatment Depends on the Severity of Hearing Dysfunction in Symptomatic Infants with Congenital Cytomegalovirus Infection.

Although earlier studies have shown that antiviral treatment regimens using valganciclovir (VGCV) improved hearing function in some infants with congenital cytomegalovirus (CMV) infection; its efficacy on the severity of hearing dysfunction is unclear. We conducted a prospective study among 26 infants with congenital CMV infections from 2009 to 2018. Oral VGCV (32 mg/kg/day) was administered for 6 weeks (November 2009 to June 2015; n = 20) or 6 months (July 2015 to March 2018, n = 6). Hearing function was evaluated by measuring the auditory brainstem response before VGCV treatment and at 6 months. Hearing dysfunction, defined as a V-wave threshold >40 dB, was categorized into: most severe, ≥91 dB; severe, 61⁻90 dB; and moderate, 41⁻60 dB. Hearing improvement was defined as a decrease of ≥20 dB from the pretreatment V-wave threshold. Of 52 ears in 26 infants with congenital CMV infection, 29 (56%) had hearing dysfunction, and of 29 ears, 16 (55%) improved after VGCV treatment. Although, 16 (84%) of 19 ears with moderate or severe hearing dysfunction improved after treatment (p < 0.001), 10 ears with the most severe form did not. In conclusion, VGCV treatment is effective in improving moderate and severe hearing dysfunction in infants with congenital CMV infection.

MicroRNA-124 inhibits TNF-α- and IL-6-induced osteoclastogenesis.

Receptor activator for nuclear factor κB ligand (RANKL)-independent osteoclastogenic pathway was reported recently. MicroRNA (miR)-124 has been known to suppress RANKL-dependent osteoclastogenesis by inhibiting NFATc1 expression. However, whether miR-124 regulates a RANKL-independent pathway has not been elucidated. In this study, we examined whether a RANKL-independent pathway is regulated by miR-124 in addition to the RANKL-dependent one. Using osteoclastogenic culture and pit-formation assay, we found that a miR-124 mimic inhibited osteoclastogenesis in mouse bone marrow-derived macrophages stimulated by TNF-α, IL-6, and M-CSF in the presence of osteoprotegerin. We also showed that the expression levels of osteoclast-specific genes and NFATc1 protein were suppressed in the miR-124 mimic-transfected cells by performing quantitative-polymerase chain reaction and western blotting. Our results indicate that miR-124 is important in inhibiting both RANKL-dependent and -independent osteoclast differentiation by suppressing NFATc1-mediated pathway.

Sequence analyses of variable cytomegalovirus genes for distinction between breast milk- and transfusion-transmitted infections in very-low-birth-weight infants.

BACKGROUND: Cytomegalovirus (CMV) transmission to very-low-birth-weight infants (VLBWIs) sometimes induces serious clinical symptoms. Although breast milk is considered a major source of transmission, transfusion-transmitted CMV (TT-CMV) infection is often suspected when CMV disease develops after transfusion. Thus, it is clinically important to distinguish between transfusion-transmitted and breast milk-transmitted CMV infections. STUDY DESIGN AND METHODS: Study A: The incidence of acquired CMV transmission was prospectively investigated in 65 VLBWIs. Study B: To determine the transmission routes in 18 TT-CMV-suspected VLBWIs who had been reported in our hemovigilance system, we performed polymerase chain reaction for CMV DNA in fed breast milk and/or repository blood samples related to transfused leukoreduced blood products. Furthermore, we evaluated the identity of CMV strains in patients' urine/blood samples and fed breast milk by sequence analyses of variable CMV genes UL139 and UL146. RESULTS: Study A: Acquired CMV infection was found in 4 of 65 VLBWIs (6.2%). Study B: CMV DNA was detected in fed breast milk for 12 of 14 TT-CMV-suspected cases, for which breast milk was available. Furthermore, CMV DNA sequence-matching rates between fed breast milk and patients' urine/blood for both UL139 and UL146 genes were 100% or nearly 100% in 11 patients. In contrast, repository blood samples for 11 of 14 patients were CMV DNA negative. CONCLUSION: CMV is principally transmitted through breast milk in VLBWIs. The risk of TT-CMV seems to be extremely low when using leukoreduced blood products. Sequence analyses of the variable CMV genes are useful for evaluating CMV transmission routes.

Determination of the antimicrobial susceptibility and molecular profile of clarithromycin resistance in the Mycobacterium abscessus complex in Japan by variable number tandem repeat analysis.

Mycobacterium abscessus complex, including three subspecies-M. abscessus, M. massiliense, and M. bolletii-is resistant to a variety of antibiotics so limited treatment options are available. The susceptibility of these subspecies to antimicrobial agents depends in particular on the erm(41) sequevar and rrl mutations in the 23S rRNA, which are potentially related to clarithromycin (CLR) resistance. The purpose of this study was to carry out identification and molecular characterization of these subspecies based on variable number of tandem repeats (VNTR) analysis. Twenty-four M. abscessus complex strains were identified as M. abscessus and M. massiliense and these subspecies could be discriminated between based on their resistance to CLR, as determined by truncation or mutation of erm(41) or mutation of rrl, as illustrated by their VNTR patterns. In conclusion, we confirmed that the CLR susceptibility profiles could be differentiated according to the subspecies of M. abscessus complex strains by their VNTR patterns.

ETV6-ABL1 fusion combined with monosomy 7 in childhood B-precursor acute lymphoblastic leukemia.

ETV6-ABL1 fusion is a rare but recurrent oncogenic lesion found in childhood B-cell precursor acute lymphoblastic leukemia (BCP-ALL), without an established chromosomal abnormality, and is associated with poor outcome. In ETV6-ABL1-positive cases, an in-frame fusion produced by a complex rearrangement results in constitutive chimeric tyrosine kinase activity. Monosomy 7 is also a rare and unfavorable chromosomal abnormality in childhood BCP-ALL. Here, we report a 14-year-old female BCP-ALL patient with ETV6-ABL1 fusion combined with monosomy 7. She was admitted to our hospital because of persistent fever. Bone marrow nuclear cell count on admission was 855,000/µL with 90.0% blastic cells of lymphoid morphology. Blasts were positive for CD10, CD19, CD20, CD34, cyCD79a, cyTdT, HLA-DR, and CD66c, had a karyotype of 45, XX, - 7 [18/20] and a split signal for ABL1 FISH probe (92.7%), and were sensitive to tyrosine kinase inhibitors, imatinib and dasatinib, in vitro. ETV6-ABL1 fusion transcript was identified by whole transcriptome sequencing and confirmed by RT-PCR. She was treated with the high-risk protocol based on ALL-BFM 95, achieved complete remission (CR) after induction chemotherapy, and maintained CR for 4 months. To our knowledge, this is the first report of ETV6-ABL1 fusion combined with monosomy 7 in childhood BCP-ALL.

Associations between left ventricular diastolic function and right ventricular function in patients with and without preserved left ventricular ejection fraction.

BACKGROUND: The purpose of this study was to investigate associations between right ventricular (RV) function and left ventricular (LV) diastolic function in patients with reduced LV ejection fraction (LVEF) and preserved LVEF. METHODS: A total of 139 patients who had undergone echocardiography were recruited. LV diastolic function was determined as the ratio of mitral inflow E to mitral e' lateral annular velocities (E/e'). RV function was determined as the RV index of myocardial performance (RIMP). Patients were divided into two groups: the preserved LVEF group (n = 100, LVEF ≥ 50%) and the reduced LVEF group (n = 39, LVEF <  50%). RESULTS: Associations between RV function and LV diastolic function in patients with reduced LVEF and preserved LVEF differed significantly. RIMP correlated significantly with E/e' in patients with reduced LVEF (r = 0.47, p = 0.003), but not in those with preserved LVEF (r = 0.04, p = 0.68). An important finding of the multivariate regression analysis showed that RIMP was the only independent determinant of E/e' in patients with reduced LVEF, whereas age and gender (not RIMP) was the independent determinant of E/e' in patients with preserved LVEF. CONCLUSIONS: Associations between RV function and LV diastolic function in patients with reduced LVEF and preserved LVEF differed significantly, and RV function showed a close correlation with LV diastolic function in patients with reduced LVEF, but not in those with preserved LVEF. Thus, these findings may well have clinical implications for better management of patients with reduced LVEF.

Identification of a heterozygous p.Gly568Val missense mutation in the TRPV3 gene in a Japanese patient with Olmsted syndrome: In silico analysis of TRPV3.

Olmsted syndrome is a very rare congenital disorder, characterized by palmoplantar keratoderma and periorificial keratotic lesions. Recently, TRPV3 was reported to be a causative gene of Olmsted syndrome. We identified a heterozygous missense mutation of TRPV3, c.1703G>T, p.Gly568Val, in a Japanese patient with Olmsted syndrome. To the best of our knowledge, this is the first report of a Japanese patient with Olmsted syndrome harboring a missense mutation in TRPV3. We conducted in silico analysis of TRPV3 to evaluate whether the p.Gly568Val leads to structural changes in the TRPV3 selectivity filter. The selectivity filter was shown to become dilated and hyperpermeable as a result of genetic mutation (p.Gly573Ser, p.Tr692Gly or p.Gly568Val) as well as after a change in temperature (300 K to 310 K). In silico analysis of TRPV3 could be a useful approach in predicting mutation-induced activated states of ion channels, and thus enrich our understanding of the pathogenesis of Olmsted syndrome.

[Performance Utility of High Sensitivity Quantitative Assay for HBs Antigen].

A high sensitivity quantitative assay for hepatitis B virus (HBV) surface antigen (HBsAg-HQ assay) was recently developed and is useful for earlier detection of HBV reactivation. We created HBsAg-HQ assay operational proce- dures by the sample transport system and laboratory information system. In this study, we evaluated the perfor- mance and utility of the HBsAg-HQ assay based on our operational procedures using internal quality control (IQC) data and 13,762 samples routinely measured for 8 months. The IQC data of the HBsAg-HQ assay demonstrated good accuracy (CV: 1.6-2.7%). The difference in IQC data between two of the same analyzers or several reagent lots had no clinical significance. Of 13,762 samples, HBsAg titer was negative in 12,592(91.5%) and positive in 1,169(8.5%), and HBsAg negative samples were remarkably lower(<0.001 IU/mL) than the cut-off value(0.005 IU/mL). Among 114 HBsAg weakly positive samples ranging from 0.005 to 1.000 IU/mL, false positive results occurred in 12 samples, which were converted into negative results after re-measurement. We could effectively perform carry-over prevention and dilution of high titer samples using our operational procedures. Furthermore, we performed inhibition test in 52 HBsAg weakly positive samples, and 20 samples, most of which were taken from patients with connective tissue disease or malignancy, were judged as non-specific reactivity. Taken together, our operational HBsAg-HQ assay procedures may contribute to efficient workflow for routine testing. Moreover, the HBsAg-HQ assay may be clinically useful for not only highly sensitive assays, but also for reducing false positives.

Mixed Phenotype Acute Leukemia with t(12;17)(p13;q21)/TAF15-ZNF384 and Other Chromosome Abnormalities.

The t(12;17)(p13;q11∼21) translocation is a very rare but recurrent cytogenetic aberration observed predominantly in early pre-B acute lymphoblastic leukemia (ALL) with CD19+CD10-CD33+ phenotype. This translocation was shown to form a fusion gene between TAF15 at 17q12 and ZNF384 at 12p13. On the other hand, der(1;18)(q10;q10) has been detected as a rare unbalanced whole-arm translocation leading to trisomy 1q in myeloid malignancies. We describe here the first case of mixed phenotype acute leukemia (MPAL) with a t(12;17)(p13;q21)/TAF15-ZNF384, which also had der(1;18)(q10;q10) as an additional abnormality. A 74-year-old woman was diagnosed with MPAL, B/myeloid, because bone marrow blasts were positive for myeloperoxidase, CD19, and CD22. Chromosome analysis showed 46,XX, +1,der(1;18)(q10;q10),t(2;16)(q13;q13),t(12;17)(p13;q21). Expression of the TAF15-ZNF384 fusion transcript was confirmed: TAF15 exon 6 was fused in-frame to ZNF384 exon 3. This type of fusion gene has been reported in 1 acute myeloid leukemia case and 3 ALL cases. Thus, at present, it is difficult to find a specific association between the structure of the TAF15-ZNF384 fusion gene and the leukemia phenotype. The TAF15-ZNF384 fusion may occur in early common progenitor cells that could differentiate into both the myeloid and lymphoid lineages. Furthermore, der(1;18)(q10;q10) might play some role in the appearance of an additional myeloid phenotype.

Telomeric Region of the Spinal Muscular Atrophy Locus Is Susceptible to Structural Variations.

BACKGROUND: Most patients with spinal muscular atrophy lack the survival motor neuron 1 gene (SMN1) in the telomeric region of the spinal muscular atrophy locus on chromosome 5q13. On the other hand, the copy number of SMN2, a centromeric homolog of SMN1, is increased in many of these patients. This study aimed to clarify the mechanism underlying these structural variations. METHODS: We determined the copy numbers of telomeric and centromeric genes in the spinal muscular atrophy locus of 86 patients and 22 control subjects using multiplex ligation-dependent probe amplification analysis. Then, we chose 74 patients lacking SMN1 exons 7 and 8, and compared their dataset with that of 22 control subjects retaining SMN1 exons 7 and 8. RESULTS: The SMN2 copy number was shown to vary widely and to correlate with the disease severity of the patients. Interestingly, telomeric NAIP and telomeric GTF2H2 showed similar tendencies. We also noted positive correlations among the copy number of SMN2 and the telomeric genes of the spinal muscular atrophy locus. However, the copy numbers of centromeric NAIP and centromeric GTF2H2 were stable among the patients, with both approximating a value of two. CONCLUSION: Our findings suggested that the telomeric region of the spinal muscular atrophy locus appears to be susceptible to structural variation, whereas the centromeric region is stable. Moreover, according to our results, new SMN2 copies may be generated in the telomeric region of the spinal muscular atrophy locus, supporting the SMN1-to-SMN2 gene conversion theory.