Krithika Roy

Krithika Roy
University College London | UCL · Department of Clinical and Experimental Epilepsy

PhD

About

71
Publications
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1,494
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Additional affiliations
October 2010 - December 2014
University of Toronto
Position
  • PostDoc Position

Publications

Publications (71)
Article
Full-text available
The developmental and epileptic encephalopathies (DEE) are the most severe group of epilepsies. Recently, NEXMIF mutations have been shown to cause a DEE in females, characterized by myoclonic–atonic epilepsy and recurrent nonconvulsive status. Here we used advanced neuroimaging techniques in a patient with a novel NEXMIF de novo mutation presentin...
Article
Objective To explore the phenotypic spectrum of RHOBTB2 -related disorders, and specifically to determine whether patients fulfil criteria for alternating hemiplegia of childhood (AHC), we report the clinical features of 11 affected individuals. Methods Individuals with RHOBTB2 -related disorders were identified through a movement disorder clinic...
Article
Full-text available
Idiopathic basal ganglia calcification (IBGC) or primary familial brain calcification is a rare genetic condition characterized by an autosomal dominant inheritance pattern and the presence of bilateral calcifications in the basal ganglia, thalami, cerebellum and cerebral subcortical white matter. The syndrome is genetically and phenotypically hete...
Article
OBJECTIVE: Pathogenic variants in SCN8A have been associated with a wide spectrum of epilepsy phenotypes, ranging from benign familial infantile seizures (BFIS) to epileptic encephalopathies with variable severity. Furthermore, a few patients with intellectual disability (ID) or movement disorders without epilepsy have been reported. The vast major...
Article
Full-text available
Objective: To characterize the neurologic phenotypes associated with COL4A1/2 mutations and to seek genotype-phenotype correlation. Methods: We analyzed clinical, EEG, and neuroimaging data of 44 new and 55 previously reported patients with COL4A1/COL4A2 mutations. Results: Childhood-onset focal seizures, frequently complicated by status epile...
Article
The original version of this article contained an error in the spelling of the author Erik H. Niks, which was incorrectly given as Erik Niks. This has now been corrected in both the PDF and HTML versions of the article.
Chapter
Full-text available
Mitochondrial DNA (mtDNA) polymorphisms of five sub-tribes of Adi tribe of Arunachal Pradesh (Northeast India) were examined with the aim of investigating their extent of genetic variation; genetic relationships (maternal lineage) and population structure (fission–fusion), especially changes in genetic structure as a result of migration and settlem...
Article
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The original version of this Article contained an error in the author list where the corresponding author Stéphanie Baulac was repeated twice. This has now been corrected in the HTML, the PDF was correct at the time of publication.
Article
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Purpose: To define the phenotypic and mutational spectrum of epilepsies related to DEPDC5, NPRL2 and NPRL3 genes encoding the GATOR1 complex, a negative regulator of the mTORC1 pathway METHODS: We analyzed clinical and genetic data of 73 novel probands (familial and sporadic) with epilepsy-related variants in GATOR1-encoding genes and proposed new...
Article
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Background Currently, there is limited knowledge about the genetics underlying pigmentary traits in East Asian populations. Here, we report the results of the first genome-wide association study of pigmentary traits (skin and iris color) in individuals of East Asian ancestry. Methods We obtained quantitative skin pigmentation measures (M-index) in...
Data
Distribution of skin pigmentation, expressed as M-index values, in the East Asian sample
Data
Genome-wide significant and suggestive signals observed in the genome-wide association study of skin pigmentation (M-index) and iris color (L*, a*, b* and delta values) All the regions indicated in the file have more than one genome-wide significant or suggestive marker with good imputation scores (info score >0.8).
Data
Regional plots for suggestive regions (p-value <10−5) identified in the GWAs of iris color (L* values) All these regions harbour multiple markers showing suggestive significance and good imputation.
Data
Regional plots for suggestive regions (p-value <10−5) identified in the GWAs of iris color (a* values) All these regions harbour multiple markers showing suggestive significance and good imputation scores (e.g., score info > 0.8).
Data
Table reporting allele frequencies and effect size estimates in the East Asian sample for markers known to be associated with light skin in European populations The table includes variants in the genes SLC24A5 and SLC45A2, which have very high frequencies in Europe and have been reported to have very strong effects on skin pigmentation in admixed g...
Data
Distribution of delta values (e.g., difference in color coordinates between the pupillary and ciliary regions of the iris) in the East Asian sample
Data
Regional plots for suggestive regions (p-value <10−5) identified in the GWAs of skin pigmentation All these regions harbour multiple markers showing suggestive significance and good imputation scores (e.g., score info > 0.8).
Data
QQ plots for L*, a* and b* iris color coordinates and delta values
Data
Regional plots for suggestive regions (p-value <10−5) identified in the GWAs of iris color (delta values) All these regions harbour multiple markers showing suggestive significance and good imputation scores (e.g., score info > 0.8).
Data
Scatterplots of a* and b* ( Fig. 2A), a* and L* (Fig. 2B) and b* and L* (Fig. 2C) CIELab iris color coordinates in the East Asian sample
Data
Principal Component Analysis (PCA) coordinates (axes 1 and 2) of the East Asian sample analyzed in the study, as well as the East Asian samples of the 1000 Genomes Project CDX, Chinese Dai in Xishuangbanna, KHV, Kinh in Ho Chi Minh City, Vietnam, CHB, Han Chinese in Beijing, CHS, Han Chinese South and JPT, Japanese in Tokyo.
Data
QQ plot for skin pigmentation
Data
Regional plots for suggestive regions (p-value <10−5) identified in the GWAs of iris color (b* values) All these regions harbour multiple markers showing suggestive significance and good imputation scores (e.g., score info > 0.8).
Article
Chromosomal abnormalities are often identified in people with neurodevelopmental disorders including intellectual disability, autism, and epilepsy. Ring chromosomes, which usually involve gene copy number loss, are formed by fusion of subtelomeric or telomeric chromosomal regions. Some ring chromosomes, including ring 14, 17, and 20, are strongly a...
Article
Full-text available
We performed genome-wide meta-analysis of lipid traits on three samples of Mexican and Mexican American ancestry comprising 4,383 individuals, and followed up significant and highly suggestive associations in three additional Hispanic samples comprising 7,876 individuals. Genome-wide significant signals were observed in or near CELSR2, ZNF259/APOA5...
Article
Full-text available
There are many textural elements that can be found in the human eye, including Fuchs' crypts, Wolfflin nodules, pigment spots, contraction furrows and conjunctival melanosis. Although iris surface features have been well-studied in populations of European ancestry, the worldwide distribution of these traits is poorly understood. In this paper, we d...
Article
In this study, we present a new quantitative method to measure iris colour based on high resolution photographs. We applied this method to analyze iris colour variation in a sample of individuals of East Asian, European and South Asian ancestry. We show that measuring iris colour using the coordinates of the CIELAB colour space uncovers a significa...
Article
Full-text available
Objectives The main goals of this study are to 1) quantitatively measure skin, hair, and iris pigmentation in a diverse sample of individuals, 2) describe variation within and between these samples, and 3) demonstrate how quantitative measures can facilitate genotype-phenotype association tests.Materials and Methods We quantitatively characterize s...
Article
Extreme discordant phenotype and genome-wide association (GWA) approaches were combined to explore the role of genetic variants on warfarin dose requirement in Brazilians. Patients receiving low (≤20 mg/week; n = 180) or high stable warfarin doses (≥42.5 mg/week; n = 187) were genotyped with Affymetrix Axiom(®) Biobank arrays. Imputation was carrie...
Article
Full-text available
Objectives The main goal of the study was to test the association of 18 polymorphisms located within nine pigmentation candidate genes with quantitative skin pigmentation measures collected in a sample of individuals of East Asian ancestry living in Canada (N = 419).Methods The 18 polymorphisms are located within genes that show putative signatures...
Chapter
The microRNAs (miRNAs) are small non-coding RNAs which play an important role in gene regulation and are involved in several biological functions. Studies have shown that there are several hundreds of them across (human) genome. And one miRNA may be involved in several genes and several miRNA may target a gene. In this regard it is interesting to k...
Chapter
Full-text available
The microRNAs (miRNAs) are small non-coding RNAs which play an important role in gene regulation and are involved in several biological functions. Studies have shown that there are several hundreds of them across (human) genome. And one miRNA may be involved in several genes and several miRNA may target a gene. In this regard it is interesting to k...
Article
Full-text available
Genetic association studies require a quantitative and reliable method for odor threshold assessment in order to examine the contribution of genetic variants to complex olfactory phenotypes. Our main goal was to assess the feasibility of a portable Scentroid air dilution olfactometer for use in such studies. Using the Scentroid SM110C and the SK5 n...
Preprint
Full-text available
Genetic association studies require a quantitative and reliable method for odor threshold assessment in order to examine the contribution of genetic variants to complex olfactory phenotypes. Our main goal was to assess the feasibility of a portable Scentroid air dilution olfactometer for use in such studies. Using the Scentroid SM110C and the SK5 n...
Preprint
Genetic association studies require a quantitative and reliable method for odor threshold assessment in order to examine the contribution of genetic variants to complex olfactory phenotypes. Our main goal was to assess the feasibility of a portable Scentroid air dilution olfactometer for use in such studies. Using the Scentroid SM110C and the SK5 n...
Article
Full-text available
To further understanding of the genetic basis of type 2 diabetes (T2D) susceptibility, we aggregated published meta-analyses of genome-wide association studies (GWAS), including 26,488 cases and 83,964 controls of European, east Asian, south Asian and Mexican and Mexican American ancestry. We observed a significant excess in the directional consist...
Article
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Physiological and lifestyle factors put older adults at an increased risk of vitamin D insufficiency and resulting negative health outcomes. Here we explore the vitamin D status in a sample of community dwelling older adults of diverse ancestry living in the Greater Toronto area (GTA). Two hundred and twenty-four (224) adults over 60 years of age w...
Book
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The effect of past demographic unheavals of population growth and evolutionary changes in population size on the genetic diversity of the regional subpopualations of Adi, a Tibeto-Burman speaking population of central Arunachal Pradesh, India, are studied. Demographic expansion or population growth experienced in the past from a state of equalibriu...
Chapter
Full-text available
The effect of past demographic upheavals of population growth and evolutionary changes in population size on the genetic diversity of the regional sub-tribes of Adi, a Tibeto-Burman speaking population of central Arunachal Pradesh, India are studied. Demographic expansion or population growth experienced in the past from a state of equilibirum is e...
Article
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Background: We explored the imputation performance of the program IMPUTE in an admixed sample from Mexico City. The following issues were evaluated: (a) the impact of different reference panels (HapMap vs. 1000 Genomes) on imputation; (b) potential differences in imputation performance between single-step vs. two-step (phasing and imputation) appr...
Article
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We report a genome-wide association study of type 2 diabetes in an admixed sample from Mexico City and describe the results of a meta-analysis of this study and another genome-wide scan in a Mexican-American sample from Starr County, TX, USA. The top signals observed in this meta-analysis were followed up in the Diabetes Genetics Replication and Me...
Article
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An understanding of the genetic affinity and the past history of the tribal populations of India requires the untangling of the confounding influences of language, ethnicity, and geography on the extant diverse tribes. The present study examines the genetic relationship of linguistically (Dravidian, Austro-Asiatic, and Tibeto-Burman) and ethnically...
Article
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Indian subcontinent harbours both the human mtDNA macrohaplogroups M and N, of which M is the most prevalent. In this study, we discuss the overall distribution of the various haplogroups and sub-haplogroups of M among the different castes and tribes to understand their diverse pattern with respect to geographical location and linguistic affiliatio...
Data
DA- NJ phylogenies, based on 9 loci, depicting the genetic relationship between 22 Tibeto-Burman populations of India. (0.09 MB TIF)
Data
Sample size, geographical distribution, linguistic affiliation and the subsistence pattern of the studied populations. (0.10 MB DOC)
Data
DA-NJ phylogenetic trees, based on 15 loci, depicting the genetic relationship between the Adi sub-groups. (0.05 MB TIF)
Data
DA- NJ phylogenies, based on 9 loci, depicting the genetic relationship between 50 populations of India and East/Southeast Asia. (0.18 MB TIF)
Article
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Indian populations show mitochondrial DNA macrohaplogroups M and N. Among the various haplogroups of N, haplogroup R and its sub-haplogroup U are predominant among the diverse populations. An overview of about 130 studied populations reveals wide diversity of haplogroup R and its sub-haplogroup U among varied ethnic status and different linguistic...
Article
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Tibeto-Burman populations of India provide an insight into the peopling of India and aid in understanding their genetic relationship with populations of East, South and Southeast Asia. The study investigates the genetic status of one such Tibeto-Burman group, Adi of Arunachal Pradesh based on 15 autosomal microsatellite markers. Further the study e...
Article
Full-text available
The study examines the regional genetic diversity among 23 Arunachal Pradesh tribes based on 2 loci (ABO and PTC). The results show wide variation in allele frequencies. The 'r' allele shows higher frequency (than 'p' and 'q') and show geographical variation. The results of NJ tree and PCA plot show separation of tribal groups that fairly correspon...
Article
Full-text available
Fifteen autosomal STR loci were analyzed in 223 healthy individuals belonging to three remote, isolated Tibeto-Burman speaking sub tribes namely, Panggi, Komkar and Padam of Adi tribe of Arunachal Pradesh, India. The analyzed markers exhibited a high degree of polymorphism in the studied populations. Statistical parameters of forensic interest; obs...
Article
Full-text available
Isolated tribes in remote areas are important for genetic studies, and one such little known subtribe of the Adi tribe, namely, the Adi Panggi (Pangi) of the Upper Siang District of Arunachal Pradesh, India, was studied for surname distribution to deduce the deviation from random mating and genetic kinship between villages. The estimates of homonym...
Article
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We studied the distribution of ABO blood group frequencies of the Galo and Mishing subtribes of the Adi tribal cluster in East Siang District, Arunachal Pradesh, India, in order to investigate the intertribal and temporal allelic variation. Blood groups O and AB showed higher frequencies (28.4%, 27.4%) in the Galo, whereas group O (45%) was predomi...
Article
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POPULATION: Two Tibeto-Burman-speaking Adi tribal populations of Arunachal Pradesh, India, Adi Pasi (n=121) from Upper Siang district, and Adi Minyong (n=33) from East Siang district were analyzed for polymorphisms at 15 microsatellite loci. The populations belong to Mongoloid ethnicity and are of special significance in genetic studies due to thei...
Article
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A overall review of haplogroup distribution of Y-chromosome scenario of Indian populations have been summarized to get into the pattern and trends from diverse regions among castes and tribes.
Article
Full-text available
The study examines the regional genetic diversity among 23 Arunachal Pradesh tribes based on 2 loci (ABO and PTC). The results show wide variation in allele frequencies. The 'r' allele shows higher frequency (than 'p' and 'q') and show geographical variation. The results of NJ tree and PCA plot show separation of tribal groups that fairly correspon...
Article
Full-text available
We studied the distribution of ABO blood groups among three little known subtribes of the Adi tribe, namely, the Panggi, Komkar, and Padam, of the East and Upper Siang districts of Arunachal Pradesh, India. Blood group O was the predominant group in the Komkar and Padam, whereas group A was the predominant group in the Panggi. Blood group AB was fo...
Article
Full-text available
The Tibeto-Burman (TB) populations are one of the four major linguistic population groups of India. They are considered belonging to different stocks and show wide variation in culture and language; however, their genetic relationship, antiquity and migration history among the regional populations has been little investigated. Molecular genetic stu...