Cav-1 (Caveolin-1) and Arterial Remodeling in Adult Moyamoya Disease

Background and Purpose- Moyamoya disease (MMD) is a unique cerebrovascular occlusive disease characterized by progressive stenosis and negative remodeling of the distal internal carotid artery (ICA). We hypothesized that cav-1 (caveolin-1)-a protein that controls the regulation of endothelial vesicular trafficking and signal transduction-is associated with negative remodeling in MMD. Methods- We prospectively recruited 77 consecutive patients with MMD diagnosed via conventional angiography. Seventeen patients with intracranial atherosclerotic stroke and no RNF213 mutation served as controls. The outer distal ICA diameters were examined using high-resolution magnetic resonance imaging. We evaluated whether the degree of negative remodeling in the patients with MMD was associated with RNF213 polymorphism, cav-1 levels, or various clinical and vascular risk factors. We also investigated whether the derived factor was associated with negative remodeling at the cellular level using the tube formation and apoptosis assays. Results- The serum cav-1 level was lower in the patients with MMD than in the controls (0.47±0.29 versus 0.86±0.68 ng/mL; P=0.034). The mean ICA diameter was 2.48±0.98 mm for the 126 affected distal ICAs in patients with MMD and 3.84±0.42 mm for the asymptomatic ICAs in the controls ( P<0.001). After adjusting for confounders, cav-1 levels (coefficient, 1.018; P<0.001) were independently associated with the distal ICA diameter in patients with MMD. In vitro analysis showed that cav-1 downregulation suppressed angiogenesis in the endothelial cells and induced apoptosis in the smooth muscle cells. Conclusions- Our findings suggest that cav-1 may play a major role in negative arterial remodeling in MMD.

Phenotypic association of presence of a somatic GNAQ mutation with port-wine stain distribution in capillary malformation

BACKGROUND

A somatic mutation of GNAQ (c.548G>A, p.Arg183Gln) plays a key role in capillary malformation development. The present study aimed to evaluate clinical manifestations of port-win stain (PWS) associated with this genetic mutation.

METHODS

Skin tissue was obtained from 70 patients with capillary malformation who had been treated with excision for lesions. Droplet digital polymerase chain reaction was used to quantify the abundance of cells with the GNAQ mutation.

RESULTS

The GNAQ mutation was found in 50 patients. Patients with lesions involving upper facial region, which included forehead, eyebrow, and upper eyelid, showed a significantly higher rate of positive GNAQ mutation than those not involving it. Cases with facial PWS involving all three facial regions (upper, middle, and lower) showed significantly higher positive rate of GNAQ mutation compared to those involving one or two.

CONCLUSIONS

Presence of the somatic mutation GNAQ p.Arg183Gln might be associated with clinical manifestations of PWS.

Prevalence of fragile X-associated tremor/ataxia syndrome: A survey of essential tremor patients with cerebellar signs or extrapyramidal signs

OBJECTIVES

In screening studies of Western patients with cerebellar dysfunction, FMR1 premutations have been detected. A screening study of East Asian patients with presumed essential tremor (ET) did not detect these mutations, possibly because the ET patients did not closely mimic the phenotype of fragile X-associated tremor/ataxia syndrome (FXTAS). The aim of this study was to estimate the prevalence of FMR1 premutations in a carefully recruited group of ET patients with additional phenotypic features of FXTAS.

MATERIALS AND METHODS

From April 2014 to April 2018, we prospectively recruited patients with ET diagnoses from three tertiary care centers. Demographic and clinical data were collected, as well as data on presence of cerebellar signs and extrapyramidal signs (EPS). Tremor, cerebellar signs, and EPS were evaluated using appropriate clinical rating scales. For ET patients with additional cerebellar signs or EPS, FMR1 mutation analysis and brain magnetic resonance imaging were performed.

RESULTS

Six hundred and three ET patients were recruited. Cerebellar signs or EPS were present in 168 (27.9%) of 603. FMR1 CGG repeat analysis was performed in 74 of 168 patients. Fifty-two of 74 had cerebellar signs only, three had EPS only, and 19 had both neurologic abnormalities. Two patients had a FMR1 premutation and fulfiled both clinical and radiological criteria of FXTAS.

CONCLUSIONS

Two (2.7%) of 74 patients with presumed ET and additional neurological features were discovered to have FXTAS. The possibility of FXTAS should be considered in patients with ET who exhibit mild cerebellar signs or EPS.

Analysis of dementia-related gene variants in APOE ε4 noncarrying Korean patients with early-onset Alzheimer's disease

There is a genetic overlap among various neurodegenerative diseases that cause dementia. We analyzed dementia-related gene variants in 60 apolipoprotein E ε4 non-carrying Korean patients with early-onset Alzheimer's disease. Thirty-one dementia-related genes were screened by exome sequencing. Among the 60 patients, three likely pathogenic variants (LPVs) and 1 variant of uncertain significance (VUS) were identified in PSEN1. In addition, two LPVs in TYROBP (c.141del) and PINK1 (c.1220G>A) and 17 VUS were found in other dementia-causing genes. Two variants in SORL1 and TREM2 were identified that were associated with Alzheimer's disease. In this study, we identified 5 (8.3%) LPVs and 18 (30%) VUSs in known dementia-related genes in apolipoprotein E ε4 noncarrying Korean patients with early-onset Alzheimer's disease.

A novel SMAD6 variant in a patient with severely calcified bicuspid aortic valve and thoracic aortic aneurysm

BACKGROUND

Bicuspid aortic valve (BAV) is the most common congenital heart defect with a prevalence of 1%-2% in the general population. NOTCH1, SMAD6, and GATA5 are associated with BAV in humans, but few cases have been reported that did not involve NOTCH1. Here, we identified novel in-frame variants in SMAD6 (c.1168_1173dup; p.Gly390_Ile391dup) in a BAV patient, who presented with dilatation of the ascending aorta and severe calcification of the aortic valve.

METHODS

Twenty BAV associated genes were screened by exome sequencing. Functional effects of SMAD6 variant were investigated using bone morphogenetic protein (BMP) signaling assays through in vitro functional study.

RESULTS

Exome sequencing revealed he had novel in-frame variants in the SMAD6 gene (c.1168_1173dup; p.Gly390_Ile391dup). SMAD6 is known to be an inhibitory protein in the BMP signaling pathway. In vitro functional study of the p.Gly390_Ile391dup variant revealed impaired inhibition of BMP signaling and BMP-induced alkaline phosphatase activity.

CONCLUSION

In conclusion, we identified a novel SMAD6 variant causing a severely calcified BAV and TAA, which contributes to our understanding of the clinical and genetic background of SMAD6-related BAV.

Abstract TP160: The Ring Finger Protein 213 Variant and Characteristics of Plaque, Vascular Remodeling and Hemodynamics in Patients With Intracranial Atherosclerotic Stroke: A High-Resolution Mri and Hemodynamic Study

Background: Intracranial atherosclerotic stroke is prevalent in Asians. We hypothesized patients with the Ring Finger protein 213 ( RNF213 ) variant, a susceptibility locus for moyamoya disease in East Asians, have different neuroimaging characteristics in terms of vessel wall and hemodynamics.

Methods: We analyzed consecutive patients with ischemic events in the middle cerebral artery (MCA) distribution and relevant plaque on the distal internal carotid artery or proximal MCA on high-resolution MRI (HR-MRI). Patients with carotid/cardiac sources of embolism or angiographic features of moyamoya disease were excluded. HR-MRI features (e.g., outer vessel diameters and plaque characteristics) and fractional flow (as measured by adjusted signal intensity ratio on time-of-flight MRA) were compared between RNF213 p.Arg4810Lys variant carriers and non-carriers.

Results: Of 144 patients included, 44 (29.9%) patients had the RNF213 variant. Clinical characteristics including age, gender, and vascular risk factors were not different between RNF213 variant carriers and non-carriers. However, outer vessel diameter was smaller in RNF213 variant carriers than in non-carriers (p<0.0001 for MCA of relevant stenosis, p<0.0001 for contralateral side, and p<0.001 for basilar artery). Other HR-MRI features including plaque morphology were not different. Fractional flow was diminished in patients with a smaller diameter of the intracranial arteries with the similar degree of stenosis.

Conclusions: The RNF213 variant may be associated with vasculogenesis but not with atherogenesis. Patients with this variant had small intracranial arteries predisposing hemodynamic compromise in the presence of intracranial atherosclerosis. Beside anti-atherosclerotic strategies, further studies are warranted to develop a novel therapeutic strategies against RNF213 vasculopathy in Asians.

Multimodal imaging analyses in patients with genetic and sporadic forms of small vessel disease

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is thought to be a pure genetic form of subcortical vascular cognitive impairment (SVCI). The aim of this study was to compare white matter integrity and cortical thickness between typical CADASIL, a genetic form, and two sporadic forms of SVCI (with NOTCH3 and without NOTCH3 variants). We enrolled typical CADASIL patients (N = 11) and SVCI patients [with NOTCH3 variants (N = 15), without NOTCH3 variants (N = 101)]. To adjust the age difference, which reflects the known difference in clinical and radiologic courses between typical CADASIL patients and SVCI patients, we constructed a W-score of measurement for diffusion tensor image and cortical thickness. Typical CADASIL patients showed more frequent white matter hyperintensities in the bilateral posterior temporal region compared to SVCI patients (p < 0.001, uncorrected). We found that SVCI patients, regardless of the presence of NOTCH3 variants, showed significantly greater microstructural alterations (W-score, p < 0.05, FWE-corrected) and cortical thinning (W-score, p < 0.05, FDR-corrected) than typical CADASIL patients. In this study, typical CADASIL and SVCI showed distinct anatomic vulnerabilities in the cortical and subcortical structures. However, there was no difference between SVCI with NOTCH3 variants and SVCI without NOTCH3 variants.

The Impact of APOE ɛ4 in Alzheimer's Disease Differs According to Age

We evaluated how the impact of apolipoprotein E4 (APOE4) differs according to age in Alzheimer's disease (AD) patients. We recruited 846 AD patients and 815 cognitively normal controls and categorized into three groups with respect to their age (<65, 65-74, and ≥75 years). We evaluated the risk of AD in APOE4 carriers and compared cortical thickness and cognitive function according to APOE4 status in each age group. At the point of this study, in young (<65 years) AD, APOE4 noncarriers had the most severe frontal and perisylvian atrophy, while in old (≥75 years) AD, APOE4 carriers had the most severe medial temporal atrophy. In AD under 75 years, APOE4 noncarriers and heterozygotes showed worse performance in language, visuospatial, and frontal function compared to homozygotes, while, in old (≥75 years) AD, APOE4 homozygotes showed worse performance in memory compared to noncarriers. As the detrimental effects of APOE4 seen in older AD patients were not found in younger AD patients, we suggest that some unrevealed factors are associated with cortical atrophy and non-amnestic cognitive dysfunction in young AD with APOE4 noncarriers.

A De Novo RAPGEF2 Variant Identified in a Sporadic Amyotrophic Lateral Sclerosis Patient Impairs Microtubule Stability and Axonal Mitochondria Distribution

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease that is frequently linked to microtubule abnormalities and mitochondrial trafficking defects. Whole exome sequencing (WES) of patient-parent trios has proven to be an efficient strategy for identifying rare de novo genetic variants responsible for sporadic ALS (sALS). Using a trio-WES approach, we identified a de novo RAPGEF2 variant (c.4069G>A, p.E1357K) in a patient with early-onset sALS. To assess the pathogenic effects of this variant, we have used patient-derived skin fibroblasts and motor neuron-specific overexpression of the RAPGEF2-E1357K mutant protein in Drosophila. Patient fibroblasts display reduced microtubule stability and defective microtubule network morphology. The intracellular distribution, ultrastructure, and function of mitochondria are also impaired in patient cells. Overexpression of the RAPGEF2 mutant in Drosophila motor neurons reduces the stability of axonal microtubules and disrupts the distribution of mitochondria to distal axons and neuromuscular junction (NMJ) synapses. We also show that the recruitment of the pro-apoptotic protein BCL2-associated X (BAX) to mitochondria is significantly increased in patient fibroblasts compared with control cells. Finally, increasing microtubule stability through pharmacological inhibition of histone deacetylase 6 (HDAC6) rescues defects in the intracellular distribution of mitochondria and BAX. Overall, our data suggest that the RAPGEF2 variant identified in this study can drive ALS-related pathogenic effects through microtubule dysregulation.

De novo mutations in COL4A5 identified by whole exome sequencing in 2 girls with Alport syndrome in Korea

Alport syndrome (ATS) is an inherited glomerular disease caused by mutations in one of the type IV collagen novel chains (α3, α4, and α5). ATS is characterized by persistent microscopic hematuria that starts during infancy, eventually leading to either progressive nephritis or end-stage renal disease. There are 3 known genetic forms of ATS, namely X-linked ATS, autosomal recessive ATS, and autosomal dominant ATS. About 80% of patients with ATS have X-linked ATS, which is caused by mutations in the type IV collagen α5 chain gene, COL4A5. Although an 80% mutation detection rate is observed in men with X-linked ATS, some difficulties do exist in the genetic diagnosis of ATS. Most mutations are point mutations without hotspots in the COL4A3, COL4A4, and COL4A5 genes. Further, there are insufficient data on the detection of COL4A3 and COL4A4 mutations for their comparison between patients with autosomal recessive or dominant ATS. Therefore, diagnosis of ATS in female patients with no apparent family history can be challenging. Therefore, in this study, we used whole-exome sequencing (WES) to identify mutations in type IV collagen in 2 girls with glomerular basement membrane structural changes suspected to be associated with ATS; these patients had no relevant family history. Our results revealed de novo c.4688G>A (p.Arg1563Gln) and c.2714G>A (p.Gly905Asp) mutations in COL4A5. Therefore, we suggest that WES is an effective approach to obtain genetic information in ATS, particularly in female patients without a relevant family history, to detect unexpected DNA variations.

Genetic variants of PARK genes in Korean patients with early-onset Parkinson's disease

Early-onset Parkinson's disease (EOPD) can be linked to different genetic backgrounds depending on the disease characteristics. In Korean patients with EOPD, however, only 5 PARK genes have been tested. We recruited 70 patients with EOPD from 4 hospitals in Korea, and 12 PARK genes were screened via multigene panel sequencing. Large insertions or deletions were confirmed by multiplex ligation-dependent probe amplification. We found 20 rare variants (2 in SNCA, 2 in PRKN, 6 in LRRK2, 3 in PINK1, 1 in DJ1, 4 in FBX07, 1 in HTRA2, and 1 in EIG4G1) in 20 subjects regardless of heterogeneity. Two pathogenic variants (SNCA in 2 subjects and DJ1 in one) were from 3 subjects, and 7 likely pathogenic variants (SNCA, LRRK2, FBXO7, and 2 in PINK1 and PRKN) from 7. Akinetic-rigid subtype and dystonia were more common in patients with EOPD with rare variants than in those without rare variants. Multigene panel tests can be effective at identifying genetic variants in patients with EOPD. In addition, we suggest there are different genetic backgrounds in patients with EOPD.

Comparison between DiaPlexQ™ STI6 and GeneFinder™ STD I/STD II multiplex Real-time PCR Kits in the detection of six sexually transmitted disease pathogens

BACKGROUND

The DiaPlexQ™ STI6 Detection Kit (DiaPlexQ; Solgent Co., Ltd., Daejeon, South Korea) is a multiplex real-time PCR assay for the detection of the following sexually transmitted disease (STD) pathogens: Chlamydia trachomatis, Neisseria gonorrhoeae, Mycoplasma hominis, Trichomonas vaginalis, Ureaplasma urealyticum, and Mycoplasma genitalium. We compared the performance of the DiaPlexQ assay with the GeneFinder™ STD I (CT/NG/UU) and STD II (MG/MH/TV) Multiplex Real-time PCR Kits (GeneFinder; Infopia Co., Ltd., Anyang, South Korea).

METHODS

We evaluated the performance of the DiaPlexQ assay in comparison to that of GeneFinder using 1106 clinical specimens (542 genital swabs and 564 urine samples). The analytical performance of the DiaPlexQ assay, including the limit of detection (LOD) and analytical specificity, was evaluated using reference strains.

RESULTS

The positive percent agreement, negative percent agreement, and kappa value between the two assays were 96.6%-99.4%, 98.2%-99.8%, and 0.93%-0.99%, respectively. No cross-reactivity was observed in a collection of 41 different microorganisms and the LOD of the DiaPlexQ assay ranged from 1 to 10 copies/reaction for each microorganism.

CONCLUSION

The DiaPlexQ assay showed comparable performance to that of the GeneFinder assay so that it can be used for the screening and diagnosis of non-viral curable STD pathogens.

Repeated Intrathecal Mesenchymal Stem Cells for Amyotrophic Lateral Sclerosis

Objective

To assess the safety and efficacy of 2 repeated intrathecal injections of autologous bone marrow–derived mesenchymal stem cells (BM‐MSCs) in amyotrophic lateral sclerosis (ALS).

Methods

In a phase 2 randomized controlled trial (NCT01363401), 64 participants with ALS were randomly assigned treatments (1:1) of riluzole alone (control group, n = 31) or combined with 2 BM‐MSC injections (MSC group, n = 33). Safety was assessed based on the occurrence of adverse events. The primary efficacy outcome was changes in Amyotrophic Lateral Sclerosis Functional Rating Scale–Revised (ALSFRS‐R) score from baseline to 4 and 6 months postinjection. Post hoc analysis includes investigation of cerebrospinal fluid biomarkers and long‐term survival analysis.

Results

Safety rating showed no groupwise difference with absence of serious treatment‐related adverse events. Mean changes in ALSFRS‐R scores from baseline to 4 and 6 months postinjection were reduced in the MSC group compared with the control group (4 months: 2.98, 95% confidence interval [CI] = 1.48–4.47, p < 0.001; 6 months: 3.38, 95% CI = 1.23–5.54, p = 0.003). The MSC group showed decreased proinflammatory and increased anti‐inflammatory cytokines. In good responders, transforming growth factor β1 significantly showed inverse correlation with monocyte chemoattractant protein‐1. There was no significant difference in long‐term survival between groups.

Interpretation

Repeated intrathecal injections of BM‐MSCs demonstrated a possible clinical benefit lasting at least 6 months, with safety, in ALS patients. A plausible action mechanism is that BM‐MSCs mediate switching from pro‐ to anti‐inflammatory conditions. A future randomized, double‐blind, large‐scale phase 3 clinical trial with additional BM‐MSC treatments is required to evaluate long‐term efficacy and safety. Ann Neurol 2018;84:361–373

Drug susceptibility patterns of Mycobacterium abscessus and Mycobacterium massiliense isolated from respiratory specimens

In this study, we aimed to retrospectively investigate and compare the drug susceptibility patterns of two major Mycobacterium abscessus complex (MABC) species; M. abscessus and M. massiliense. A total of 546 MABC respiratory isolates (277 M. abscessus and 269 M. massiliense) from 2011 to 2016 were analyzed in this study. We estimated minimum inhibitory concentrations (MICs) using the broth microdilution method, and we calculated MIC₅₀ and MIC₉₀ values from the MIC distribution. Both M. abscessus and M. massiliense were highly susceptible to amikacin and linezolid. For M. abscessus, the proportions of inducible and acquired resistance to clarithromycin were 68.6% and 12.3%, respectively. Only 15.2% of M. abscessus remained susceptible at day 14. On the other hand, none of the M. massiliense showed inducible resistance and 6.3% showed acquired resistance to clarithromycin. A total of 92.6% of the M. massiliense remained susceptible at day 14. The resistance rate of M. abscessus to moxifloxacin (90.3%) was significantly higher than that of M. massiliense (83.3%; p = 0.016). These susceptibility differences may explain the divergent treatment outcomes between patients with pulmonary disease caused by these two species.

Analysis of frontotemporal dementia, amyotrophic lateral sclerosis, and other dementia-related genes in 107 Korean patients with frontotemporal dementia

To identify pathogenic variants in 107 Korean patients with sporadic frontotemporal dementia (FTD), 46 genes related to FTD, amyotrophic lateral sclerosis, and other dementias were screened by next-generation sequencing. Hexanucleotide repeats in C9orf72 gene were also tested by repeat-primed polymerase chain reaction. Next-generation sequencing revealed one known pathogenic variant (c.708+1G>A) in the GRN gene in a patient with behavioral variant FTD (bvFTD). In addition, a novel in-frame deletion (c.2675_2683del) in the CSF1R gene was identified in a patient with bvFTD who had severe bifrontal atrophy with frontal subcortical white matter changes. Novel compound heterozygous variants in the AARS2 gene, c.1040+1G>A and c.636G>A (p.Met212Ile), were found in a patient with bvFTD. Forty-six variants of uncertain significance were detected in other patients. None of the patients had expanded hexanucleotide repeats in C9orf72. These results show that pathogenic variants of known FTD genes are rare in Korean FTD patients but the CSF1R and AARS2 genes should be screened for a genetic diagnosis of FTD or other dementias.

Prospective monitoring of adenovirus infection and type analysis after allogeneic hematopoietic cell transplantation: A single-center study in Korea

Background

Epidemiologic studies of human adenovirus (HAdV) in allogeneic hematopoietic cell transplantation (HCT) recipients have been conducted mostly in European countries where HAdV 2 (species C) has been most prevalent in the community. The main objective of this study was to investigate the epidemiology and the characteristics of HAdV infection in Korean allogeneic HCT recipients (<19 years).

Methods

In a prospective study from April 2012 to September 2015, HAdV in blood, urine, and stool specimens were monitored weekly from transplantation to day 100 or after if clinically suspected. HAdV infection was defined as positive HAdV PCR result in any specimens regardless of symptoms.

Results

A total of 1734 specimens were collected from 57 consecutively enrolled recipients. The cumulative incidence of HAdV infection at day 100, and 1 year was 10%, and 20%, and the incidence of viremia was 2% and 6%, respectively. The median onset time from HCT to viremia was 221 days (range, 7‐596 days). All viremia cases were caused by only HAdV 3 (species B), whereas several types were detected in stool. Among patients with HAdV infection, lower absolute lymphocyte counts and extensive chronic graft‐vs‐host disease were associated with viremia (P = .028 and P = .006, respectively).

Conclusions

Compared to western studies, this study demonstrated a lower incidence and delayed onset of HAdV infections and HAdV 3 was most prevalent in Korea.

Significance of circulating Epstein-Barr virus DNA monitoring after remission in patients with extranodal natural killer T cell lymphoma

Circulating Epstein-Barr virus (EBV)-DNA has been established as a useful parameter for diagnosis and predicting prognosis in patients with extranodal natural killer T cell lymphoma (ENKTL); however, the role of monitoring of circulating EBV-DNA after complete remission (CR) is not well established. From January 2008 to August 2016, 328 ENKTL patents were enrolled in 2 lymphoma cohorts. Of 171 patients achieved a CR, 81 had available monitoring data for circulating EBV-DNA with negative post-treatment EBV-DNA. Measurement of circulating EBV-DNA was performed from unfractionated whole blood and calculated according to WHO international standards. Median duration of follow-up was 40.4 months. In 31 of the 81 patients (38.8%), circulating EBV-DNA was detected at least once during follow-up, and 16 of these patients (51.6%) experienced relapse. In contrast, only 7 out of 50 (14.0%) patients with consistently undetectable circulating EBV-DNA experienced relapse (p < 0.001). In multivariate analysis, positive conversion of circulating EBV-DNA was the only independent prognostic factor for occurrence of relapse (HR = 6.552, p < 0.001), progression-free survival (HR = 4.549, p = 0.01), and overall survival (HR = 8.726, p < 0.001). Patients with a higher level of circulating EBV-DNA than 3310 IU/mL (3.52 log₁₀ IU/mL) showed a strong tendency to relapse (73.3 vs. 31.3%, p = 0.019). In conclusion, positive conversion of circulating EBV-DNA was a valuable indicator of relapse and inferior survival, especially if the level was higher than 3310 IU/mL in ENKTL patients had achieved CR. Close follow-up is necessary for patients developed detectable circulating EBV-DNA after remission.

Frequency of hereditary neuropathy with liability to pressure palsies (HNPP) due to 17p11.2 deletion in a Korean newborn population

Hereditary neuropathy with liability to pressure palsies (HNPP) is an autosomal dominant disorder mainly due to a deletion of chromosome 17p11.2 including PMP22 (PMP22 Del HNPP). The prevalence of HNPP is estimated to be 0.84 to 16 per 100,000, but could be underestimated because of the mild symptoms of HNPP. In this study, we estimated the prevalence of PMP22 Del HNPP in a Korean newborn population who underwent next-generation sequencing (NGS)-based copy number variation (CNV) analysis. Of the 11,885 newborns tested by NGS-based CNV analysis, 17p11.2 deletions were found in seven samples. The prevalence of PMP22 Del HNPP was estimated to be 58.9 per 100,000 (95% confidence interval (CI), 25.8–116.5) or 1 in 1698 (95% CI, 1/909–1/5000). Our data suggest that PMP22 Del HNPP might not be uncommon at least in the Korean population.