First Report of an α Chain Variant [Hb Coombe Park (HBA2: c.382A>G)] from India, Coinherited with a Novel SERPINC1 Gene Mutation: A Double Whammy?

Coinheritance of a high oxygen affinity structural hemoglobin (Hb) variant along with a thrombophilia marker is a rare occurrence. This may lead to a multi fold increase in the risk of thrombosis in patients. We report here a first case of Hb Coombe Park (HBA2: c.382A>G; p.Lys128Glu) from India, coinherited with a novel mutation (c.839C>G; p.Ser280Ter) on the SERPINC1 gene. This coinheritance has not been reported before. Though the patient is presently asymptomatic, identification of these variants will help in genetic counseling and to decide the future course of action in case of any clinical complications.

Evolution and Utility of Preimplantation Genetic Testing for Monogenic Disorders in Assisted Reproduction - A Narrative Review

Preimplantation genetic testing (PGT) for monogenic disorders and assisted reproductive technology have evolved and progressed in tandem. PGT started with single-cell polymerase chain reaction (PCR) followed by fluorescent in situ hybridisation for a limited number of chromosomes, later called 'preimplantation genetic diagnosis (PGD) version 1'. This review highlights the various molecular genetic techniques that have evolved to detect specific inherited monogenic disorders in the preimplantation embryo. Literature review in English was performed in PubMed from 1990 to 2021, using the term 'preimplantation genetic diagnosis'. With whole-genome amplification, multiple copies of embryonic DNA were created. This helped in avoiding misdiagnosis caused by allele dropout. Multiplex fluorescent PCR analysed informative short tandem repeats (STR) and detected mutations simultaneously on automated capillary electrophoresis sequencers by mini-sequencing. Comparative genomic hybridisation (CGH) and array CGH were used for 24 chromosome aneuploidy screening. Subsequently, aneuploidies were detected by next-generation sequencing using single-nucleotide polymorphism arrays, while STR markers were used for haplotyping. 'PGD version 2' included accurate marker-based diagnosis of most monogenic disorders and detection of aneuploidy of all chromosomes. Human leukocyte antigen matching of embryos has important implications in diagnosis and cure of haemoglobinopathies and immunodeficiencies in children by means of matched related haematopoietic stem cell transplantation from an unaffected 'saviour sibling' obtained by PGT.

Detection of a novel mutation in NLRP3/CIAS1 gene in an Indian child with Neonatal-Onset Multisystem Inflammatory Disease (NOMID)

Neonatal-Onset Multisystem Inflammatory Disease (NOMID) or Chronic Infantile Neurologic Cutaneous Articular (CINCA) syndrome is a monogenic autoinflammatory disorder characterized by urticarial skin rash, fever, chronic meningitis and joint manifestations. Here we report a case of an Indian male child who presented at the age of 9 months with fever, respiratory distress, urticarial skin rash, arthritis, and neuroregression. Suspecting NOMID/CINCA syndrome, the child's blood was sent to the Jaslok Hospital and Research Centre for mutation analysis of the CIAS1/NLRP3 gene. The DNA was screened for mutations in exon 3 of CIAS1/NLRP3 gene by automated Sanger sequencing. DNA sequencing showed a novel heterozygous c.1813A➔G, p.R605G mutation in exon 3 of CIAS1/NLRP3 gene (ref no NM_001243133.1). His parents tested negative for this mutation. We therefore identified a novel de novo mutation in this family in the CIAS1/NLRP3 gene responsible for the child's clinical features.

A case-control study identifying chromosomal polymorphic variations as forms of epigenetic alterations associated with the infertility phenotype

OBJECTIVE

To study the association of chromosomal polymorphic variations with infertility and subfertility.

DESIGN

A comparative case-controlled association study using cytogenetic techniques to compare the frequency of chromosomal variations in infertile individuals versus fertile controls.

SETTING

Department of Infertility Management and Assisted Reproduction, Jaslok Hospital and Research Centre, Mumbai, India.

PATIENT(S)

760 infertile individuals and 555 fertile controls.

INTERVENTION(S)

ICSI, IUI, karyotyping, inverted 4',6-diamidino-2-phenylindole (DAPI), CBG banding.

MAIN OUTCOME MEASURE(S)

Frequency of chromosomal polymorphic variations in infertile individuals undergoing infertility treatment versus fertile individuals.

RESULT(S)

A highly statistically significant increase in the frequency of total chromosomal variants in infertile women (28.31% vs. 15.16%) and infertile men (58.68% vs. 32.55%) was observed. The frequency of 9qh+ was statistically significantly increased in women with primary infertility (16.22% vs. 6.41%) and in men with severe male factor infertility (14.69% vs. 4.25%). A highly statistically significant increase in the frequency of Yqh+ was observed in men whose wives had a bad obstetric history (30.20% vs. 12.74%).

CONCLUSION(S)

The statistically significantly higher incidence of heterochromatic variations found in infertile individuals stresses on the need to evaluate their role in infertility and subfertility. Potential epigenetic, genetic, and chromosomal modifications could be associated with certain complex disorders such as infertility and bad obstetric history.

Polymorphic variants on chromosomes probably play a significant role in infertility

Polymorphic variants on chromosomes are considered 'normal', as heterochromatin has no coding potential and nucleolar organizing regions (NOR) contain genes coding for rRNA. Variants have been reported in infertility and recurrent abortions. With refined molecular techniques, genes for fertility and viability are now thought to reside in heterochromatin. DNA sequence analysis of human chromosome 9 has shown that it is highly structurally polymorphic, with many intrachromosomal and interchromosomal duplications, and contains the largest autosomal block of heterochromatin. Transcriptional activation of constitutive heterochromatic domains of the human genome in response to environmental stress was reported recently. Heat shock triggers the assembly of nuclear stress bodies on the pericentromeric heterochromatin of human chromosomes including chromosome 9. These are characterized by an epigenetic status typical of euchromatic regions. On acrocentric chromosomes, NOR-associated protein count and morphology was reported to separate benign and malignant melanocytic lesions. Hence all variants may not be 'normal'. The present study of karyotyping 842 individuals attending an IVF clinic with primary infertility or repeated miscarriages, showed polymorphic variants in 28.82% of males and 17.19% of females, which was quite high. It is suggested that variants should not be ignored by cytogeneticists. Screening prospective gamete donors for chromosome variants may help enhance the success of IVF.

Preimplantation genetic diagnosis of chromosomal abnormalities by multicolour fluorescence in situ hybridisation

Preimplantation genetic diagnosis (PGD) is an early diagnosis of genetic disorders, prior to the onset of pregnancy. PGD incorporates the latest techniques in assisted reproduction and molecular genetics. Embryos or oocytes are biopsied during culture in vitro and genetic analysis is carried out on the blastomeres or polar bodies. Embryos shown to be free of the genetic disease under investigation are transferred to the uterus. Multicolour fluorescence in situ hybridisation (FISH) is used to diagnose numerical and certain structural abnormalities of chromosomes in the embryo. The common probes used are for chromosomes 13, 18, 21, X and Y. FISH can also be used for PGD of translocations, when one of the parents is a carrier. PGD was carried out recently in 4 cases using multicolour FISH. In one of the embryos, trisomy 18 was detected. Tetraploidy was seen in another embryo. Only chromosomally normal embryos were transferred back to the uterus. Care has to be taken while interpreting FISH signals as the signal may be split, diffused, superimposed or in a different focus.