Development and validation of a novel panel of 16 STR markers for simultaneous diagnosis of β-thalassemia, aneuploidy screening, maternal cell contamination detection and fetal sample authenticity in PND and PGD/PGS cases

The Impact of Leukemia on the Detection of Short Tandem Repeat (STR) Markers

INTRODUCTION

Short tandem repeats (STRs) have been used for various identity typing methods worldwide. They have high discrimination power in human identification in forensics, paternity testing, missed personal identification, genetic diseases, and gene regulatory functions. They have also been used to detect and monitor the stability of diseases, including various types of cancer. This study aimed to investigate the impact of leukemia on the detection and stability of STR markers.

METHODS

DNA was isolated from 30 participants (15 with chronic myeloid leukemia( CML) and 15 healthy controls) and used to amplify STR markers using specific primers.

RESULTS

We found that the blood of those with leukemia had more 9.3 and 9 alleles at the tyrosine hydroxylase 1 (TH01) marker than the blood of the healthy control samples. The results of this study will help researchers understand leukemia's effect on the detection and stability of STR markers in leukemic patients compared to healthy individuals.

CONCLUSION

Our results demonstrate that STR markers could become useful in genetic studies of leukemia cases.

Comprehensive Mutation Analysis and Report of 12 Novel Mutations in a Cohort of Patients with Spinal Muscular Atrophy in Iran

Spinal muscular atrophies (SMAs) are a heterogeneous group of neuromuscular diseases characterized by loss of motor neurons, muscle weakness, hypotonia and muscle atrophy, with different modes of inheritance; however, the survival motor neuron 1 (SMN1) gene is predominantly involved. The aims of the current study were to clarify the genetic basis of SMA and determine the mutation spectrum of SMN1 and other associated genes, in order to provide molecular information for more accurate diagnosis and future prospects for treatment. We performed a comprehensive analysis of 5q SMA in 1765 individuals including 528 patients from 432 unrelated families with at least one child with suspected clinical presentation of SMA. Copy number variations of the SMN1 and SMN2 genes and linkage analysis were performed using multiplex ligation-dependent probe amplification (MLPA) and short tandem repeat (STR) markers linked to the SMN1 gene. Cases without mutation in the SMA locus on 5q were analyzed for the DNAJB2, IGHMBP2, SIGMAR1 and PLEKHG5 genes using linked STR markers. Sanger sequencing of whole genes was performed for cases with homozygous haplotypes. Whole-genome sequencing (WGS) and whole-exome analysis was conducted for some of the remaining cases. Mutations in the SMN1 gene were identified in 287 (66.43%) families including 269 patients (62.26%) with homozygous deletion of the entire SMN1 gene. Only one of the patients had a homozygous point mutation in the SMN1 gene. Among the remaining families, three families showed mutations in either the DNAJB2, SIGMAR1 or PLEKHG5 genes, which were linked using STR analysis and Sanger sequencing. From 10 families who underwent WGS, we found six homozygous point mutations in six families for either the TNNT1, TPM3, TTN, SACS or COL6A2 genes. Two mutations in the PLA2G6 gene were also found in another patient as compound heterozygous. This rather large cohort allowed us to identify genotype patterns in Iranian 5q SMA patients. The process of identifying 11 mutations (9 novel) in 9 different genes among non-5q SMA patients shows the diversity of genes involved in non-5q SMA in Iranians. Genotyping of patients with SMA is essential for prenatal and preimplantation genetic diagnosis (PGD), and may be very helpful for guiding treatment, with the advent of new, more effective, albeit very expensive, therapies. Also, combining linkage analysis was shown to be beneficial in many ways, including sample authenticity and segregation analysis, and for ruling out maternal cell contamination during prenatal diagnosis (PND).