Persistent colonization of Candida auris among inpatients rescreened as part of a weekly surveillance program.

We established a surveillance program to evaluate persistence of C. auris colonization among hospitalized patients. Overall, 17 patients (34%) had ≥1 negative result followed by a positive test, and 7 (41%) of these patients had ≥2 consecutive negative tests.

Current Assistive Devices Usage and Recommendations for a Future Artificial Vision Prosthesis among Patients with Severe Visual Impairment Due to Inherited Retinal Diseases.

Patients with inherited retinal diseases (IRDs) utilize various adaptive techniques and devices designed to assist them with activities of daily living (ADLs). The purpose of this study was to assess the assistive devices used by patients with IRDs, the difficulties they face despite these devices, and their recommendations for a future visual prosthesis. In collaboration with blind patients, an online survey was developed and administered to adults with IRDs and visual acuities of 20/400 to no light perception in the better-seeing eye. We analyzed data from 121 survey respondents (aged 18 to >80 years). Five respondents were Argus II prosthesis recipients. The most commonly used aids were cellular phones/tablets for reading (63.6%) as well as a sighted guide (75.0%) and a cane (71.4%) for mobility. Despite current assistive devices, participants reported continued difficulty with ADLs. Improved navigation, reading, and facial recognition were ranked the most desirable features for future visual prostheses. Argus II recipients suggested technology with improved ability to recognize objects and obstacles, detect movement, and cut out busy backgrounds. These insights are valuable in shaping the design of future prosthetic devices tailored to the needs of IRD patients.

Refractive Outcomes in Fuchs' Endothelial Corneal Dystrophy: Conventional and Femtosecond Laser-Assisted Cataract Surgery.

PURPOSE: To investigate the refractive outcomes of eyes with Fuchs' endothelial corneal dystrophy (FECD) following phacoemulsification. METHODS: This is a retrospective chart review of patients with FECD who underwent phacoemulsification. Manifest refraction at the early postoperative period (1-6 weeks) and late postoperative period (3-12 months) was collected. The spherical equivalent (SE) and variance of SE from target in diopters (D) were analyzed. RESULTS: A total of 219 eyes from 175 FECD patients (73 FLACS, 146 conventional phacoemulsification) were included. In the early postoperative period, when comparing variance from intended target, 62% (n=126) had a SE variance of ≤0.5 D, 22% (n=44) >0.5 D and ≤1 D, and 17% (n=34) >1 D. In the late postoperative period, 62% (n=85) had a SE variance of ≤0.5 D, 19% (n=26) >0.5 D and ≤1 D, and 20% (n=27) >1 D. There was no difference in the variance of SE comparing FLACS versus conventional phacoemulsification in either the early postoperative period (p=0.78) or the late postoperative period (p=0.29). CONCLUSION: Patients with mild-to-moderate FECD had favorable refractive outcomes with phacoemulsification. There was no difference in refractive outcomes in eyes with FECD between the group that underwent FLACS versus the group that underwent conventional phacoemulsification.

Endophthalmitis Caused by Streptococcus:Clinical Outcomes and Antimicrobial Susceptibilities 2014-2019.

BACKGROUND AND OBJECTIVE: To report the clinical settings, antibiotic susceptibilities, and outcomes of streptococcal endophthalmitis. PATIENTS AND METHODS: Retrospective case series evaluating culture-positive streptococcal endophthalmitis from January 1, 2014, to December 31, 2019. RESULTS: Thirty-eight eyes met study criteria. The most common clinical setting was post-glaucoma surgery (33.3%, 12/36). The most frequent isolate was Streptococcus viridans (63.2%, 24/38). Isolates were susceptible to vancomycin (100%, 36/36), ceftriaxone (100%, 28/28), and levofloxacin (100%, 36/36). Final best-corrected visual acuity was 20/150 or better in 24.1% (7/29) but 20/200 or worse in 75.9% (22/29). Enucleation was performed in 11.1% (4/36). A subset (n = 11) of cases were evaluated for streptococcal-specific virulence factors: pneumolysin was present in 18.2% (2/11), autolysin in 45.5% (5/11), and hyaluronidase in 54.5% (6/11). Clinical setting, antibacterial susceptibilities, timing of pars plana vitrectomy, and virulence factor presence were not associated with better visual outcome or enucleation rate (P > .05). CONCLUSION: Visual prognosis for streptococcal endophthalmitis is poor despite early and appropriate antibiotic treatment. [Ophthalmic Surg Lasers Imaging Retina. 2021;52:182-189.].

Treatment Outcomes of Slow Coagulation Transscleral Cyclophotocoagulation In Pseudophakic Patients with Medically Uncontrolled Glaucoma.

PURPOSE: Reporting treatment outcomes of slow coagulation transscleral cyclophotocoagulation (TSCPC) as an initial surgical intervention in pseudophakic patients with glaucoma. DESIGN: Retrospective case series. METHODS: This single academic center study reviewed 74 pseudophakic patients who had a diagnosis of glaucoma and no previous glaucoma surgeries (mean age 82.6 ± 12.5 years; mean follow-up 18.7 ± 9.1 months). The intervention used was slow coagulation continuous wave TSCPC (1250-mW power and 4-second duration). The primary outcome measure was surgical success defined as an intraocular pressure (IOP) of 6-21 mm Hg with a ≥20% reduction from baseline, no reoperation for glaucoma, and no loss of light-perception vision. Secondary outcome measures included glaucoma medication use, visual acuity (VA), and complications. RESULTS: IOP decreased from 27.5 ± 9.8 mm Hg preoperatively to 16.1 ± 6.3 mm Hg postoperatively (P < .001). The preoperative number of glaucoma medications was 4.1 ± 0.9 and 3.1 ± 1.3 post-TSCPC (P < .001). The cumulative probabilities of success at 1 and 2 years were 60.6 % and 58.5%, respectively. When patients were divided into 2 groups based on their baseline IOP being >21 mm Hg (high group) or ≤21 mm Hg (low group), success rates at 2 years were 64.9% and 45.5%, respectively (P = .144). The mean logarithm of the minimum angle of resolution VA changed from 0.70 ± 0.64 to 1.04 ± 0.87 at the last follow-up visit (P = .01). No serious complications were observed and most of the complications were mild and transient. CONCLUSIONS: Slow coagulation TSCPC has good efficiency, especially in patients with baseline IOP >21 mm Hg, and safety profile as an initial surgical intervention in pseudophakic patients with glaucoma.

Characteristics of diplopia in a pediatric population.

PURPOSE: To evaluate the characteristics of diplopia in children at a single tertiary eye care center. METHODS: The medical records of patients with diplopia onset at age 18 years or younger presenting during the period 2015-2018 were reviewed retrospectively. Demographic information, clinical characteristics, diagnoses, treatment, and outcome data were collected. The exact χ2 test was used to compare groups and select post hoc analyses were performed using the Fisher exact or exact χ2 tests. RESULTS: A total of 244 patients (average age, 12.2 years at presentation) were included. The most common clinical diagnoses were nonparalytic strabismus (49.2%), trauma (9.4%), and cranial nerve palsies (9%). There was no statistically significant difference in median age of diplopia onset in those with nonparalytic strabismus, cranial nerve palsies, and vision- or life-threatening conditions. There was a statistically significant difference in timing of onset of diplopia at presentation in vision- or life-threatening conditions compared to nonparalytic strabismus (P < 0.0001) and cranial nerve palsies (P = 0.01) and for neurologic symptoms in vision- or life- threatening conditions compared to nonparalytic strabismus (P = 0.032) and cranial nerve palsies (P = 0.0051). In patients with more than one neurologic symptom, the majority (58.3%) had a vision- or life-threatening condition. Initial interventions included observation (28.7%), prisms (18.4%), updating refractive correction (14.3%), and strabismus surgery (11.1%). In patients with follow-up data, 5.3% had resolution of diplopia prior to their clinic visit, and 46.6% had resolution after initial intervention. CONCLUSIONS: In our study cohort, most children who presented with diplopia had nonemergent conditions. In those with life-threatening conditions, diplopia tended to have an acute onset and associated neurologic signs and visual symptoms.

Tube Versus Trabeculectomy IRISⓇ Registry 1-Year Composite Outcome Analysis with Comparisons to the Randomized Controlled Trial.

PURPOSE: This study compared 1-year results for the composite treatment outcome from the Tube Versus Trabeculectomy (TVT) randomized controlled trial (RCT) to those from an IRISⓇ (Intelligent Research In Sight) Registry cohort of analogous eyes. DESIGN: Retrospective clinical study with comparison to an RCT. METHODS: Subjects' eyes in the IRIS Registry received either a glaucoma drainage implant (tube) or underwent trabeculectomy after a previous trabeculectomy and/or cataract extraction and had data for 1-year follow-up analyses. OUTCOME: Eyes were classified as failing if they had hypotony (intraocular pressure (IOP) ≤5 mm Hg) or inadequate IOP control (IOP >21 mm Hg or not reduced at least 20% below baseline) on 2 consecutive follow-up visits after 3 months, a reoperation for glaucoma, or no light perception vision and as successful otherwise. Failure risk was compared by treatment, demographic, and clinical variables and was compared to analogous failure risks from the TVT RCT. RESULTS: The TVT IRIS Registry cohort included 419 eyes, 236 tube eyes (56.3%) and 183 trabeculectomy eyes (43.7%). In this cohort, there was no significant failure risk difference (12.3% for tube eyes and 16.4% for trabeculectomy eyes, P = 0.231). Comparing the studies, there was a significantly greater risk of failure in the TVT IRIS Registry tube eyes than in the TVT RCT tube eyes (3.8%; P <.001). Reasons for treatment failure included reoperations for glaucoma (none in the TVT RCT at 1 year). CONCLUSIONS: Our results were different from those in the TVT RCT. Possible reasons include non-Baerveldt tubes, greater severity among tube eyes, and practice patterns that reflect real-world data, which are different than those in RCTs.

Treatment Outcomes of Primary Transscleral Cyclophotocoagulation.

PURPOSE: To report treatment outcomes of primary transscleral cyclophotocoagulation (TSCPC) in glaucomatous eyes. DESIGN: Retrospective noncomparative study. PARTICIPANTS: Forty-eight eyes with a diagnosis of glaucoma and no previous incisional ocular surgery. METHODS: Continuous-wave TSCPC was applied to the ciliary body. MAIN OUTCOME MEASURES: The primary outcome measure was surgical success defined as an IOP ≤ 21 mmHg and reduced by 20% or more from baseline, IOP > 5 mmHg, no reoperation for glaucoma, and no loss of light perception vision. Secondary outcome measures included visual acuity (VA) and complications. RESULTS: Glaucoma eyes were stratified into 2 groups: (1) those with pretreatment IOP >21 mmHg (high group) and (2) those with pretreatment IOP ≤ 21 mmHg (low group). Mean ± standard deviation (SD) IOP at baseline was 30.6 ± 6.3 mmHg in the high group and 16.2 ± 2.8 mmHg in the low group. Mean ± SD number of glaucoma medications at baseline was 4.1 ± 0.8 in the high group and 3.6 ± 1.1 in the low group. Based on our success criteria, the cumulative probability of success during the first year of follow-up was 58.3% in the high group and 28.1% in the low group (P = 0.052). Postoperative mean IOP was significantly lower than baseline IOP in the high group at 1-, 3-, 6-, 12-, and 18-month postoperative visits (P < 0.05). No significant change was observed in IOP at follow-up visits after 1 month in the low IOP group. Throughout the first year of follow-up, both groups required fewer glaucoma medications compared with baseline at the 1-, 3-, 6-, and 12-month postoperative visits (P < 0.05). The most frequent cause of postoperative decrease in VA was cataract in 9 eyes. Decrease in vision resulting from glaucoma was observed in 3 eyes. Complications included prolonged inflammation (11 eyes), iris neovascularization (2 eyes), cystoid macular edema (4 eyes), and hyphema (1 eye). No severe or long-term complications were observed. CONCLUSIONS: Continuous-wave TSCPC was effective in lowering IOP in glaucoma patients without prior incisional ocular surgery whose disease was recalcitrant to medical therapy, particularly those with baseline IOP of more than 21 mmHg.

Comparison of Skin Antiseptic Agents and the Role of 0.01% Hypochlorous Acid.

BACKGROUND: Hypochlorous acid (HA) has both anti-microbial and wound-healing properties with a growing role for utilization in pre-procedural care on the face. OBJECTIVES: The authors sought to compare the antiseptic property of 0.01% HA solution, 5% povidone iodine (PI), 4% chlorhexidine gluconate (CHG), and 70% isopropyl alcohol (IPA) antiseptic on facial skin. METHODS: This was a prospective single-center clinical trial. RESULTS: A total of 21 participants were recruited. Bacterial growth was seen in CHG (10%), IPA (71%), PI (81%), and HA (95%) of specimens (P < 0.001). CHG had less growth compared with HA (P = <0.001), IPA (P = <0.001), and PI (P = <0.001). No difference in bacterial growth was noted between HA and IPA (P = 0.063) or HA and PI (P = 0.25). Significant differences in mono-microbial and poly-microbial growth were seen between HA and IPA (P = 0.046) and HA and CHG (P = <0.001). Staphylococcus epidermidis grew less frequently in CHG (10%), followed by IPA (29%), PI (71%), and HA (71%). Staphylococcus capitis grew less frequently in CHG (0%), followed by PI (14%), HA (24%), and IPA (29%). CONCLUSIONS: CHG reduced the bacterial growth compared with HA, PI, and IPA. However, HA, PI, and IPA had insignificant differences in bactericidal effects. Our study provides a supporting role of HA to be considered as an antiseptic.

The Tube Versus Trabeculectomy IRIS® Registry Study: Cohort Selection and Follow-up and Comparisons to the Randomized Controlled Trial.

PURPOSE: To assess the feasibility of replicating a randomized controlled trial (RCT) with a cohort of eyes, from IRIS® Registry data, analogous to the Tube Versus Trabeculectomy (TVT) RCT cohort and compare characteristics and follow-up. DESIGN: Comparison of RCT and IRIS Registry cohorts and follow-up. METHODS: We identified a cohort of IRIS Registry eyes (2013-2017) that received either a glaucoma drainage implant (tube) or trabeculectomy after a previous trabeculectomy and/or cataract extraction; extracted clinical and demographic characteristics for baseline surgery and follow-up visits through 1 year; and compared treatment groups in the IRIS Registry cohort and this cohort to the TVT RCT cohort. RESULTS: The IRIS Registry cohort included 419 eyes: 183 (43.7%) trabeculectomy; 236 (56.3%) tube. There were significant differences between treatment groups, including race (White: trabeculectomy 61.8%, tube 44.9%; Black: trabeculectomy 20.8%, tube 35.6%; P = .003) and the percentage of follow-up visits completed (trabeculectomy 88.4%, tube 83.8%, P = .004). There were also significant differences between the TVT IRIS Registry cohort and the TVT RCT cohort in the percentage of follow-up visits completed (IRIS Registry 85.6%, RCT 96.1%, P < .001) and in the probability of having a 1-year follow-up visit (IRIS Registry 81.4%, RCT 89.2%, P = .011). CONCLUSION: The TVT IRIS Registry cohort had several significant treatment group differences at baseline, whereas there had been none in the TVT RCT cohort. Follow-up in the TVT IRIS Registry cohort was inferior to that of the TVT RCT. Some data needed to refine the selection of eyes for the cohort were not available in the IRIS Registry.

Refractive Outcomes of Four-Point Scleral Fixation of Akreos AO60 Intraocular Lens Using Gore-Tex Suture.

BACKGROUND/OBJECTIVE: To determine the refractive outcomes after 4-point scleral fixation of the Akreos AO60 intraocular lens with Gore-Tex suture. METHODS: This was a single referral center, multi-surgeon, retrospective consecutive case series. A total of 63 eyes met the inclusion criteria for having received surgical implantation of the Akreos AO60 intraocular lens with Gore-Tex suture from August 2014 to December 2018. Exclusion criteria included all ocular pathology that precluded an accurate refraction, concurrent ocular surgery, poor corrected pre-operative visual potential, among other factors. Main outcome measures included post-operative uncorrected visual acuity (VA), best-corrected VA, and spherical equivalent deviation from target. RESULTS: Mean pre-operative BCVA was 0.67 ± 0.64 LogMAR (20/93 Snellen). Mean final post-operative BCVA was 0.17 ± 0.18 (20/28 Snellen) and mean final post-operative UCVA was 0.31 ± 0.22 (20/41 Snellen). Mean post-operative spherical equivalent was -0.57 D. Mean post-operative astigmatism was 0.85 D. CONCLUSION: Refractive outcomes after secondary implantation with Akreos AO60 are favorable in eyes with good visual potential.

Investigating Vascular Complexity and Neurogenic Alterations in Sectoral Regions of the Retina in Patients With Cognitive Impairment.

Evidence is accumulating that cognitive function, and visual impairment may be related. In this pilot study, we investigated whether multifractal dimension and lacunarity analyses performed in sectoral regions of the retina may reveal changes in patients with cognitive impairment (CI) that may be masked in the study considering the whole retinal branching pattern. Prospective age-matched subjects (n = 69) with and with no CI and without the presence of any ophthalmic history were recruited (age > 55+ years). The Montreal Cognitive Assessment (MoCA) was used to measure CI, and full-field electroretinogram (ERG) was performed. Also, visual performance exams were conducted using the Rabin cone contrast test (CCT). Quantification of the retinal structure was performed in retinal fundus images [45 o field of view (FOV), optic disk centered] with excellent quality for all individuals [19 healthy controls (HC) and 20 patients with CI] after evaluating the inclusion and exclusion criteria in all study participants recruited (n = 69). The skeletonized vasculature network that comprised the whole branching pattern observable in the full 45° FOV was obtained for each image and divided into nine equal regions (superotemporal, superior, superonasal, macular, optic disk, nasal, inferotemporal, inferior, and inferonasal). The multifractal behavior was analyzed by calculating the generalized dimension Dq (Do, D1, and D2), the lacunarity parameter (Λ), and singularity spectrum f(α) in the nine sectoral skeletonized images as well as in the skeletons that comprised the whole branching pattern observable in the full 45° FOV. The analyses were performed using the ImageJ program together with the FracLac plug-in. Independent sample t-tests or Mann Whitney U test and Pearson correlation coefficient were used to find associations between all parameters in both groups. The effect size (Cohen's d) of the difference between both groups was also assessed. A p-value < 0.05 was considered statistically significant. Significant correlations between multifractal and Λ parameters with the MoCA and implicit time ERG-parameter were observed in the regional analysis. In contrast, no trend was found when considering the whole retinal branching pattern. Analysis of combined structural-functional parameters in sectoral regions of the retina, instead of individual retinal biomarkers, may provide a useful clinical marker of CI.

Joint Analysis of Nuclear and Mitochondrial Variants in Age-Related Macular Degeneration Identifies Novel Loci TRPM1 and ABHD2/RLBP1.

Purpose: Presently, 52 independent nuclear single nucleotide polymorphisms (nSNPs) have been associated with age-related macular degeneration (AMD) but their effects do not explain all its variance. Genetic interactions between the nuclear and mitochondrial (mt) genome may unearth additional genetic loci previously unassociated with AMD risk. Methods: Joint effects of nSNPs and selected mtSNPs were analyzed by two degree of freedom (2df) joint tests of association in the International AMD Genomics Consortium (IAMDGC) dataset (17,832 controls and 16,144 advanced AMD cases of European ancestry). Subjects were genotyped on the Illumina HumanCoreExome array. After imputation using MINIMAC and the 1000 Genomes Project Phase I reference panel, pairwise linkage disequilibrium pruning, and quality control, 3.9 million nSNPs were analyzed for interaction with mtSNPs chosen based on association in this dataset or publications: A4917G, T5004C, G12771A, and C16069T. Results: Novel locus TRPM1 was identified with genome-wide significant joint effects (P < 5.0 × 10-8) of two intronic TRPM1 nSNPs and AMD-associated nonsynonymous MT-ND2 mtSNP A4917G. Stratified analysis by mt allele identified an association only in 4917A (major allele) carriers (P = 4.4 × 10-9, odds ratio [OR] = 0.90, 95% confidence interval [CI] = 0.87-0.93). Intronic and intergenic ABHD2/RLBP1 nSNPs demonstrated genome-wide significant joint effects (2df joint test P values from 1.8 × 10-8 to 4.9 × 10-8) and nominally statistically significant interaction effects with MT-ND5 synonymous mtSNP G12771A. Although a positive association was detected in both strata, the association was stronger in 12771A subjects (P = 0.0020, OR = 2.17, 95% CI = 1.34-3.60). Conclusions: These results show that joint tests of main effects and gene-gene interaction reveal associations at some novel loci that were missed when considering main effects alone.

Progression Rate From Intermediate to Advanced Age-Related Macular Degeneration Is Correlated With the Number of Risk Alleles at the CFH Locus.

PURPOSE: Progression rate of age-related macular degeneration (AMD) varies substantially, yet its association with genetic variation has not been widely examined. METHODS: We tested whether progression rate from intermediate AMD to geographic atrophy (GA) or choroidal neovascularization (CNV) was correlated with genotype at seven single nucleotide polymorphisms (SNPs) in the four genes most strongly associated with risk of advanced AMD. Cox proportional hazards survival models examined the association between progression time and SNP genotype while adjusting for age and sex and accounting for variable follow-up time, right censored data, and repeated measures (left and right eyes). RESULTS: Progression rate varied with the number of risk alleles at the CFH:rs10737680 but not the CFH:rs1061170 (Y402H) SNP; individuals with two risk alleles progressed faster than those with one allele (hazard ratio [HR] = 1.61, 95% confidence interval [CI] = 1.08-2.40, P < 0.02, n = 547 eyes), although this was not significant after Bonferroni correction. This signal was likely driven by an association at the correlated protective variant, CFH:rs6677604, which tags the CFHR1-3 deletion; individuals with at least one protective allele progressed more slowly. Considering GA and CNV separately showed that the effect of CFH:rs10737680 was stronger for progression to CNV. CONCLUSIONS: Results support previous findings that AMD progression rate is influenced by CFH, and suggest that variants within CFH may have different effects on risk versus progression. However, since CFH:rs10737680 was not significant after Bonferroni correction and explained only a relatively small portion of variation in progression rate beyond that explained by age, we suggest that additional factors contribute to progression.

The Himalayas: barrier and conduit for gene flow.

The Himalayan mountain range is strategically located at the crossroads of the major cultural centers in Asia, the Middle East and Europe. Although previous Y-chromosome studies indicate that the Himalayas served as a natural barrier for gene flow from the south to the Tibetan plateau, this region is believed to have played an important role as a corridor for human migrations between East and West Eurasia along the ancient Silk Road. To evaluate the effects of the Himalayan mountain range in shaping the maternal lineages of populations residing on either side of the cordillera, we analyzed mitochondrial DNA variation in 344 samples from three Nepalese collections (Newar, Kathmandu and Tamang) and a general population of Tibet. Our results revealed a predominantly East Asian-specific component in Tibet and Tamang, whereas Newar and Kathmandu are both characterized by a combination of East and South Central Asian lineages. Interestingly, Newar and Kathmandu harbor several deep-rooted Indian lineages, including M2, R5, and U2, whose coalescent times from this study (U2, >40 kya) and previous reports (M2 and R5, >50 kya) suggest that Nepal was inhabited during the initial peopling of South Central Asia. Comparisons with our previous Y-chromosome data indicate sex-biased migrations in Tamang and a founder effect and/or genetic drift in Tamang and Newar. Altogether, our results confirm that while the Himalayas acted as a geographic barrier for human movement from the Indian subcontinent to the Tibetan highland, it also served as a conduit for gene flow between Central and East Asia.

Y-STR diversity in the Himalayas.

Linguistic and ethnic diversity throughout the Himalayas suggests that this mountain range played an important role in shaping the genetic landscapes of the region. Previous Y-chromosome work revealed that the Himalayas acted as a biased bidirectional barrier to gene flow across the cordillera. In the present study, 17 Y-chromosomal short tandem repeat (Y-STR) loci included in the AmpFlSTR® Yfiler kit were analyzed in 344 unrelated males from three Nepalese populations (Tamang, Newar, and Kathmandu) and a general collection from Tibet. The latter displays the highest haplotype diversity (0.9990) followed by Kathmandu (0.9977), Newar (0.9570), and Tamang (0.9545). The overall haplotype diversity for the Himalayan populations at 17 Y-STR loci was 0.9973, and the corresponding values for the extended (11 loci) and minimal (nine loci) haplotypes were 0.9955 and 0.9942, respectively. No Y-STR profiles are shared across the four Himalayan collections at the 17-, 11-, and nine-locus resolutions considered, indicating a lack of recent gene flow among them. Phylogenetic analyses support our previous findings that Kathmandu, and to some extent Newar, received significant genetic influence from India while Tamang and Tibet exhibit limited or no gene flow from the subcontinent. A median-joining network of haplogroup O3a3c-M134 based on 15 Y-STR loci from our four Himalayan populations suggests either a male founder effect in Tamang, possibly from Tibet, or a recent bottleneck following their arrival south of the Himalayas from Tibet leading to their highly reduced Y single-nucleotide polymorphism and Y-STR diversity. The genetic uniqueness of the four Himalayan populations examined in this study merits the creation of separate databases for individual identification, parentage analysis, and population genetic studies.