Identification of a Novel Homozygous Mutation in PRDM12 Gene in a Patient with Hereditary Sensory and Autonomic Neuropathy Type VIII.

Hereditary sensory autonomic neuropathy type VIII (HSAN-VIII) is a rare genetic disease that occurs due to mutations in the PRDM12 gene. Here, we describe a novel homozygous mutation c.826_840dupTGCAACCGCCGCTTC (p.Cys276_Phe280dup) on exon 5 in the PRDM12 gene identified by WES and confirmed using Sanger sequencing method.

Prevalence of Chromosomal Abnormalities in Iranian Patients with Infertility.

BACKGROUND: The numerical and structural abnormalities of chromosomes are the most common cause of infertility. Here, we evaluated the prevalence and types of chromosomal abnormalities in Iranian infertile patients. METHODS: We enrolled 1750 couples of reproductive age with infertility, who referred to infertility clinics in Tehran during 2014- 2019, in order to perform chromosomal analysis. Peripheral blood samples were obtained from all couples and chromosomal abnormalities were evaluated by G-banded metaphase karyotyping. In some cases, the detected abnormalities were confirmed using fluorescence in-situ hybridization (FISH). RESULTS: We detected various chromosomal abnormalities in 114/3500 (3.257%) patients with infertility. The prevalence of chromosomal abnormalities was 44/114 (38.596%) among infertile females and 70/114 (61.403%) among infertile males. Structural chromosomal abnormalities were found in 27/1750 infertile females and 35/1750 infertile males. Numerical chromosomal abnormalities were found in 17/1750 of females and 35/1750 of males. The 45, XY, rob (13;14) (p10q10) translocation and Klinefelter syndrome (47, XXY) were the most common structural and numerical chromosomal abnormalities in the Iranian infertile patients, respectively. CONCLUSION: In general, we found a high prevalence of chromosomal abnormalities in Iranian patients with reproductive problems. Our study highlights the importance of cytogenetic studies in infertile patients before starting infertility treatments approaches.

Identification of a novel homozygous mutation in the DDR2 gene from a patient with spondylo-meta-epiphyseal dysplasia by whole exome sequencing.

OBJECTIVES: The spondylo-meta-epiphyseal dysplasia (SMED) short limbs-hand type is a rare autosomal recessive disease, which is characterized by premature calcification leading to severe disproportionate short stature and various skeletal changes. Defective function of a conserved region encoding discoidin domain receptor tyrosine kinase 2 (DDR2 protein) by the discoidin domain-containing receptor 2 (DDR2 gene) is cause of this disease. The purpose of present study was to investigate disease-causing mutations on DDR2 gene in an Iranian family with SMED, and predict the DDR2 protein molecular mechanism in development of SMED. MATERIALS AND METHODS: In the present study, we evaluated a 2-year-old male with SMED. Detection of genetic changes in the studied patient was performed using Whole-Exome Sequencing (WES). PCR direct sequencing was performed for analysis of co-segregation of variants with the disease in family. Finally, in silico study was performed for further identification of molecular function of the identified genetic variant. RESULTS: We detected a novel splice-site mutation (NM_001014796: exon9: c.855+1G>A; NM_006182: exon8: c.855+1G>A) in DDR2 gene of the studied patient using WES. This mutation was exclusively detected in patients with homozygous SMED, not in healthy people. The effects of detected mutation on functions of DDR2 protein was predicted using in silico study. CONCLUSION: The causative mutation in studied patient with SMED was identified using Next-generation sequencing (NGS), successfully. The identified novel mutation in DDR2 gene can be useful in prenatal diagnosis (PND) of SMED, preimplantation genetic diagnosis (PGD), and genetic counseling.

Identification of Two Novel Mutations in PKHD1 Gene from Two Families with Polycystic Kidney Disease by Whole Exome Sequencing.

BACKGROUND: Polycystic kidney disease (PKD) is an autosomal recessive disorder resulting from mutations in the PKHD1 gene on chromosome 6 (6p12), a large gene spanning 470 kb of genomic DNA. OBJECTIVE: The aim of the present study was to report newly identified mutations in the PKHD1 gene in two Iranian families with PKD. MATERIALS AND METHODS: Genetic alterations of a 3-month-old boy and a 27-year-old girl with PKD were evaluated using whole-exome sequencing. The PCR direct sequencing was performed to analyse the co-segregation of the variants with the disease in the family. Finally, the molecular function of the identified novel mutations was evaluated by in silico study. RESULTS: In the 3 month-old boy, a novel homozygous frameshift mutation was detected in the PKHD1 gene, which can cause PKD. Moreover, we identified three novel heterozygous missense mutations in ATIC, VPS13B, and TP53RK genes. In the 27-year-old woman, with two recurrent abortions history and two infant mortalities at early weeks due to metabolic and/or renal disease, we detected a novel missense mutation on PKHD1 gene and a novel mutation in ETFDH gene. CONCLUSION: In general, we have identified two novel mutations in the PKHD1 gene. These molecular findings can help accurately correlate genotype and phenotype in families with such disease in order to reduce patient births through preoperative genetic diagnosis or better management of disorders.

Association of a novel homozygous mutation in the HMGCS2 gene with an HMGCSD in an Iranian patient.

BACKGROUND: 3-Hydroxy-3-methylglutaryl-CoA (HMG-CoA) synthase 2 gene (HMGCS2) encodes a mitochondrial enzyme catalyzing the first reaction of ketogenesis metabolic pathway which provides lipid-derived energy for various organs during times of carbohydrate deprivation, such as fasting. Mutations in this gene are responsible for HMG-CoA synthase deficiency (HMGCSD). The aim of present study was to investigate the association of mutation in the HMGCS2 gene with HMGCSD in a patient with atypical symptoms. METHODS: The clinical and genetic features of an 8-months-old girl with HMGCSD were evaluated. Molecular genetic testing was conducted using whole-exome sequencing (WES) in order to identify potential disease-causing mutation. The WES finding was confirmed by the polymerase chain reaction (PCR) amplification of the target sequence carried out for the patient and her parents. The PCR products were subjected to direct sequencing using forward and reverse specific primers corresponding to the HMGCS2 gene. RESULTS: A novel homozygous missense mutation (c.266G>A p.Gly89Asp) was detected in the HMGCS2 gene. Sanger sequencing along with co-segregation analysis of all family members confirmed this novel pathogenic germline mutation. The mutant gene was found to be pathogenic by bioinformatics analysis. CONCLUSION: To our best knowledge, this is the first report of HMGCSD in Iran which would expand our knowledge about the mutational spectrum of the HMGCS2 gene and the phenotype variations of the disease.

Identification of Two Novel Mutations in the ATM Gene from Patients with Ataxia-Telangiectasia by Whole Exome Sequencing.

BACKGROUND: Ataxia telangiectasia (AT) is one of the most common autosomal recessive hereditary ataxia presenting in childhood. The responsible gene for AT designated ATM (AT, mutated) encodes a protein which is involved in cell cycle checkpoints and other responses to genotoxicity. We describe two novel disease-causing mutations in two unrelated Iranian families with Ataxia-telangiectasia. METHODS: The probands including a 6-year-old female and an 18-year-old boy were diagnosed with Ataxia-telangiectasia among two different Iranian families. In this study, Whole-Exome Sequencing (WES) was employed for the detection of genetic changes in probands. The analysis of the co-segregation of the variants with the disease in families was conducted using PCR direct sequencing. RESULTS: Two novel frameshift mutations, (c.4236_4236del p. Pro1412fs) and (c.8907T>G p. Tyr2969Ter) in the ataxia telangiectasia mutated ATM gene were detected using Whole-Exome Sequencing (WES) in the probands. These mutations were observed in two separate A-T families. CONCLUSION: Next-generation sequencing successfully identified the causative mutation in families with ataxia-telangiectasia. These novel mutations in the ATM gene reported in the present study could assist genetic counseling, Preimplantation Genetic Diagnosis (PGD) and prenatal diagnosis (PND) of AT.