JAK2, CALR, and MPL Mutation Profiles in Colombian patients with BCR-ABL Negative Myeloproliferative Neoplasms

Background

Among the chronic myeloproliferative neoplasms (MPNs) not associated with BCR-ABL mutations are polycythemia vera, primary myelofibrosis, and essential thrombocythemia. These diseases are caused by mutations in genes, such as the JAK2, MPL, and CALR genes, which participate in regulating the JAK-STAT signaling pathway.

Objective

This study aimed to establish the frequencies of mutations in the JAK2, MPL, and CALR genes in a group of Colombian patients with a negative clinical diagnosis of BCR-ABL chronic myeloproliferative neoplasms.

Methods

The JAK2 V617F and MPL W515K mutations and deletions or insertions in exon 9 of the CALR gene were analyzed in 52 Colombian patients with polycythemia vera, primary myelofibrosis, and essential thrombocythemia.

Results

The JAK2V617F mutation was carried by 51.9% of the patients, the CALR mutation by 23%, and the MPL mutation by 3.8%; 23% were triple-negative for the mutations analyzed. In these neoplasms, 6 mutation types in CALR were identified, one of which has not been previously reported. Additionally, one patient presented a double mutation in both the CALR and JAK2 genes. Regarding the hematological results for the mutations, significant differences were found in the hemoglobin level, hematocrit level, and platelet count among the three neoplasms.

Conclusion

Thus, this study demonstrates the importance of the molecular characterization of the JAK2, CALR and MPL mutations in Colombian patients (the genetic context of which remains unclear in the abovementioned neoplasms) to achieve an accurate diagnosis, a good prognosis, adequate management, and patient survival.

A non-coding RNASEH1 gene variant associates with type 1 diabetes and interacts with HLA tagSNPs in families from Colombia

OBJECTIVES

RNASEH1 gene has recently been associated with type 1 diabetes (T1D) in Colombia. The purpose of this study was to fine mapping the putative functional variant in RNASEH1 and testing its interaction with HLA tagSNPs.

METHODS

Two-hundred nuclear families with T1D were included in this study. Probands were tested for GAD65 and IA-2 autoantibodies. Genotyping was performed using 20 coding tagSNPs uncovered through Sanger sequencing (N = 96), in addition to 23 tagSNPs chosen from 1000genomes to cover the extent of the gene region. Also, 45 tagSNPs for classic HLA alleles associated with T1D were also genotyped. The transmission disequilibrium test (TDT) was used to test for association and a multiple testing correction was made using permutation. Interaction between RNASEH1 variants and HLA was evaluated by means of the M-TDT test.

RESULTS

We identified 20 variants (15 were novel) in the 96 patients sequenced. None of these variants were in linkage disequilibrium. In total, 43 RNASEH1 variants were genotyped in the 200 families. Association between T1D and rs7607888 was identified (P = .002). Haplotype analysis involving rs7607888 variant revealed even stronger association with T1D (most significative P = .0003). HLA tagSNPs displayed stronger associations (OR = 6.39, 95% CI = 4.33-9.44, P-value = 9.74E-28). Finally, we found several statistically significant interactions of HLA variants with rs7607888 (P-value ranged from 8.77E-04 to 5.33E-12).

CONCLUSION

Our results verify the association of rs7607888 in RNASEH1 gene with T1D. It is also shown in the interaction between RNASEH1 and HLA for conveying risk to T1D in Northwest Colombia. Work is underway aiming to identify the actual classic HLA alleles associated with the tagSNPs tested here.

Correlating the global increase in type 1 diabetes incidence across age groups with national economic prosperity: A systematic review

BACKGROUND

The global epidemiology of type 1 diabetes (T1D) is not yet well known, as no precise data are available from many countries. T1D is, however, characterized by an important variation in incidences among countries and a dramatic increase of these incidences during the last decades, predominantly in younger children. In the United States and Europe, the increase has been associated with the gross domestic product (GDP) per capita. In our previous systematic review, geographical variation of incidence was correlated with socio-economic factors.

AIM

To investigate variation in the incidence of T1D in age categories and search to what extent these variations correlated with the GDP per capita.

METHODS

A systematic review was performed to retrieve information about the global incidence of T1D among those younger than 14 years of age. The study was carried out according to the PRISMA recommendations. For the analysis, the incidence was organized in the periods: 1975-1999 and 2000-2017. We searched the incidence of T1D in the age-groups 0-4, 5-9 and 10-14. We compared the incidences in countries for which information was available for the two periods. We obtained the GDP from the World Bank. We analysed the relationship between the incidence of T1D with the GDP in countries reporting data at the national level.

RESULTS

We retrieved information for 84 out of 194 countries around the world. We found a wide geographic variation in the incidence of T1D and a worldwide increase during the two periods. The largest contribution to this increase was observed in the youngest group of children with T1D, with a relative increase of almost double when comparing the two periods (P value = 2.5 × e^-5). Twenty-six countries had information on the incidence of T1D at the national level for the two periods. There was a positive correlation between GDP and the incidence of T1D in both periods (Spearman correlation = 0.52 from 1975-1999 and Spearman correlation = 0.53 from 2000-2017).

CONCLUSION

The incidence increase was higher in the youngest group (0-4 years of age), and the highest incidences of T1D were found in wealthier countries.

Type 1 diabetes loci display a variety of native American and African ancestries in diseased individuals from Northwest Colombia

BACKGROUND

Type 1 diabetes (T1D) is a complex disease with a higher incidence in Europeans than other populations. The Colombians Living in Medellin (CLM) is admixed with ancestry contributions from Europeans, Native Americans (NAT) and Africans (AFR).

AIM

Our aim was to analyze the genetic admixture component at candidate T1D loci in Colombian individuals with the disease.

METHODS

Seventy-four ancestry informative markers (AIMs), which tagged 41 T1D candidate loci/genes, were tested by studying a cohort of 200 Northwest Colombia diseased individuals. T1D status was classified by testing for glutamic acid decarboxylase (GAD-65 kDa) and protein tyrosine-like antigen-2 auto-antibodies in serum samples. Candidate loci/genes included HLA, INS, PTPN22, CTLA4, IL2RA, SUMO4, CLEC16A, IFIH1, EFR3B, IL7R, NRP1 and RNASEH1, amongst others. The 1,000 genome database was used to analyze data from 94 individuals corresponding to the reference CLM. As the data did not comply with a normal distribution, medians were compared between groups using the Mann-Whitney U-test.

RESULTS

Both T1D patients and individuals from CLM displayed mainly European ancestry (61.58 vs 62.06) followed by Native American (27.34 vs 27.46) and to a lesser extent the AFR ancestry (10.28 vs 10.65) components. However, compared to CLM, ancestry of T1D patients displayed a decrease of NAT ancestry at gene EFR3B (24.30 vs 37.10) and an increase at genes IFIH1 (32.07 vs 14.99) and IL7R (52.18 vs 39.18). Also, for gene NRP1 (36.67 vs 0.003), we observed a non-AFR contribution (attributed to NAT). Autoimmune patients (positive for any of two auto-antibodies) displayed lower NAT ancestry than idiopathic patients at the MHC region (20.36 vs 31.88). Also, late onset patients presented with greater AFR ancestry than early onset patients at gene IL7R (19.96 vs 6.17). An association analysis showed that, even after adjusting for admixture, an association exists for at least seven such AIMs, with the strongest findings on chromosomes 5 and 10 (gene IL7R, P = 5.56 × 10^-6 and gene NRP1, P = 8.70 × 10^-19, respectively).

CONCLUSION

Although Colombian T1D patients have globally presented with higher European admixture, specific T1D loci have displayed varying levels of Native American and AFR ancestries in diseased individuals.