Screening of IL-22 first and second introns and FOXP3 second exon for SNPs and mutations with potential role in the susceptibility of SLE in selected population

OBJECTIVE

The main objective of performing this study was the mutational analysis of Forkhead box family member (FoxP3) and Interleukin-22 (IL-22) genes and their associations with systemic lupus erythematosus (SLE).

MATERIALS AND METHODS

A total of sixty blood samples were collected from SLE patients from different hospitals in Lahore. Proforma was based on American College of Rheumatology (ACR) criteria. The total time for this research was one year (2018-2019). DNA was extracted, and FoxP3 and IL-22 genes were polymerized through PCR and further sequenced through the Sanger Sequencing method. Chromas version 2.6.6 was used for the similarity index of sequences. NG_060763 and NG_007392.1 were used as Reference Sequences of IL-22 and FoxP3 genes, respectively.

RESULTS

Three already identified Single Nucleotide Polymorphisms (SNPs) in the IL-22 gene i.e., rs2227491, rs2227485, and rs2227513, were confirmed in the sequencing results of SLE patients. Results showed that there were nine novel mutations (27.27%) in the case of the IL-22 gene in the studied genotyped samples. These SNPs had remarkably increased allele T frequency in rs2227485 and allele C frequency in rs2227491 and rs2227513. On the other hand, in the case of FoxP3 gene exon 2, there was an addition of T at position 10 in the intronic portion, thus not involved in the progression of the disease.

CONCLUSIONS

The importance of cytokine-mediated signaling pathways, such as the IL-22 gene, is thus established. Novel variants in the IL-22 gene likely contributed significantly to the development of this autoimmune disorder. The current study found that the dysregulation of the inflammatory markers in SLE is not related to the FoxP3 gene, even though FoxP3 is implicated in the tolerance process.

Deletions of SMNI gene exon 7 and NAIP gene exon 5 in spinal muscular atrophy patients in selected population

OBJECTIVE

Spinal muscular atrophy (SMA) is common among various populations because the genetic makeup is monogamous due to consanguineous marriages. Two genes, i.e., survival motor neuron (SMN1) and neuronal apoptosis inhibitory protein (NAIP) are mapped to the SMA vicinity of chromosome 5q13. The main objective of the study was to develop a solitary advanced genetic tool for the diagnosis of SMA by using SMN1 gene exon 7 and NAIP gene exon 5.

PATIENTS AND METHODS

This study involved SMA patients (n=84) belonging to different clinical features and socio-economic status. The identity of the intact NAIP gene is primarily based on the amplification of exon 5 only in those SMA patients that have a deletion of SMN1 gene exon 7. Healthy controls (n=84) were also included in this study. The mutational analysis was observed through the Sanger sequencing method, where chromatograms were observed by using Chromas version 2.6.0.

RESULTS

This study showed a higher prevalence of SMA in females than in males. NAIP gene is considered a phenotype modifier as most SMA patients (94.90%) have SMN1 exon 7 deletion along with a deletion in exon 5 of the NAIP gene. Single nucleotide conversion C-T in exon 7 of SMN1 gene leads to its complete deletion. Mutated proteins encoded by SMN1 and NAIP genes also result in degeneration and muscle weakness in SMA patients.

CONCLUSIONS

These SMA-associated gene deletions can be used as a molecular evaluation tool for pre- and postnatal diagnosis of SMA. This will be valuable when there is a need for precise and consistent results with a strong focus on quantification.

Frequent homozygous deletion of the LKB1/STK11 gene in non-small cell lung cancer

LKB1/STK11 is a tumor suppressor and a negative regulator of mammalian target of rapamycin signaling. It is inactivated in 30% of lung cancer cell lines but only 5-15% of primary lung adenocarcinomas. There is evidence that homozygous deletion (HD) of chromosome 19p at the LKB locus contributes to the inactivation of the gene in primary human lung cancers. Here, we used several complementary genetic approaches to assess the LKB1 locus in primary non-small cell lung cancers (NSCLCs). We first analyzed 124 NSCLC cases for allelic imbalance using eight microsatellite markers on chromosome 19p, which revealed an overall rate of 65% (80 of 124) loss of heterozygosity (LOH). We next used chromogenic in situ hybridization (CISH) to directly examine the chromosomal status of the LKB1 locus. In all, 65 of 124 LOH tested samples were available for CISH and 58 of those (89%) showed either loss of one copy of chromosome 19p (LOH, 40 of 65 cases, 62%) or both copies (HD 18 of 65 cases, 28%). The occurrence of HD was significantly more frequent in Caucasian (35%) than in African-American patients (6%) (P=0.04). A total of 62 of 124 samples with LOH at one or both markers immediately flanking the LKB1 gene were further analyzed by directly sequencing the complete coding region, which identified 7 of 62 (11%) tumors with somatic mutations in the gene. Jointly, our data identified total inactivation of the LKB1 gene by either HD or LOH with somatic mutation in 39% of tested samples, whereas loss of chromosome 19p region by HD or LOH at the LKB1 region occured in 90% of NSCLC.