• PRIYANKA SRIVASTAVA

      Articles written in Journal of Genetics

    • Novel mutations in the transmembrane natriuretic peptide receptor NPR-B gene in four Indian families with acromesomelic dysplasia, type Maroteaux

      PRIYANKA SRIVASTAVA MONI TUTEJA ASHWIN DALAL KAUSIK MANDAL SHUBHA R. PHADKE

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      Acromesomelic dysplasia, type Maroteaux is a disorder characterized by disproportionate short stature predominantly affecting the middle and distal segments of the upper and lower limbs. It is an autosomal recessive disorder due to mutation in NPR2 gene which impairs skeletal growth. To screen the mutations in the gene NPR2, all of its coding exons and splice junction sites were PCR amplified from genomic DNA of affected individuals of four families and sequenced. Four homozygous mutations in four different families were identified. These include three novel mutations including a deletion frameshift mutation (p.Cys586Ter), one nonsense mutation (p.Arg479Ter), one missense mutation (p.Val187Asp) and one reported missense mutation (p.Tyr338Cys). The study describes phenotypes of Indian patients and expands the mutation spectrum of the disorder.

    • Phenotypic characterization of derivative 22 syndrome: case series and review

      DEEPTI SAXENA PRIYANKA SRIVASTAVA MONI TUTEJA KAUSIK MANDAL SHUBHA R PHADKE

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      Emanuel syndrome is caused due to an additional derivative chromosome 22 and is characterized by severe intellectual disability, microcephaly, failure to thrive, preauricular tags or pits, ear anomalies, cleft or high-arched palate, micrognathia, kidney abnormalities, congenital heart defects and genital abnormalities in males. In 99% of the cases, one of the parents is a carrier of balanced translocation between chromosomes 11 and 22. It occurs due to malsegregation of the gametes with 3:1 segregation. In this case series, we describe four patients with diverse manifestations of this condition. The craniosynostosis observed in one case isa novel finding which has never been reported previously. This study aims to widen the phenotypic spectrum of Emanuel syndrome and provide cytogenetic microarray based breakpoints in two of the cases, thus supporting close clustering of the breakpoints of this common recurrent chromosomal rearrangement.

    • Cytogenetic microarray in structurally normal and abnormal foetuses: a five year experience elucidating in creasing acceptance and clinical utility

      MEENAKSHI LALLAR PRIYANKA SRIVASTAVA ARCHANA RAI DEEPTI SAXENA KAUSIK MANDAL SHUBHA R. PHADKE

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      The aim of the present study was to evaluate the diagnostic yield of prenatal cytogeneticmicroarray (CMA) in structurally normal and abnormal foetuses and record the acceptance rate of CMA for prenatal diagnosis over a course of five year. In 128 structurally normal and abnormal foetuses, CMA was performed along with foetal karyotype, after exclusion of aneuploidy by quantitative fluorescence polymerase chain reaction. The microarray was able to detect the pathogenic variants in 5.5% cases; the diagnostic yield in structurally abnormal foetuses was 8.8% and 4.7% in foetuses with a high aneuploidy risk. Balanced and unbalanced translocations, and low level mosaicism were detected. Reanalysis of variants of uncertain significance identified pathogenic variant. The study shows higher diagnostic yield in structurally abnormal cases, the importance of foetal karyotype and reanalysis in microarray. The acceptance rate of prenatal CMA increased five-fold over a period of five year.

    • Hypotonic infant with Pallister–Killian syndrome diagnosed by cytogenetic microarray, without pigmentary skin changes and malformations

      ANUP RAWOOL PRIYANKA SRIVASTAVA SHUBHA R. PHADKE

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      Pallister–Killian syndrome (PKS) is a rare genetic developmental disorder characterized, by intellectual disability, seizures,streaks of hypo- or hyperpigmentation and characteristic dysmorphic features. PKS is characterized by the presence of cytogenetic abnormality in form of a supernumerary isochromosome 12p, in a tissue limited mosaicism. The isochromosome 12p is usually not detected in karyotype done from peripheral blood. Presence of patchy pigmentary skin lesions suggest the possibility of mosaicism and karyotype from skin is done which clinches the diagnosis. We describe an infant with severe hypotonia in whom trisomy 12p was detected bychromosomal microarray performed on peripheral blood. The karyotype from blood was normal and combining this information with three copies of 12p in microarray suggests the possibility of tetrasomy12p in mosaic form. The infant did not have any skin patchy pigmentary changes and malformations and hence, the diagnosis of PKS was not clinically suspected. Cytogenetic microarray is the first test for evaluation of cases with developmental delay and intellectual disability, PKS diagnosis may come as a surprise in unsuspected caseswithout characteristic skin pigmentary abnormality and malformations.

    • Homozygosity stretches around homozygous mutations in autosomal recessive disorders: patients from nonconsanguineous Indian families

      SHUBHA R. PHADKE PRIYANKA SRIVASTAVA PANKAJ SHARMA, ARCHANA RAI SUZENA MASIH

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      India has a large heterogeneous population with its unique social and genetic characteristics. Tradition of marriage betweenspecific caste groups have produced unique characteristics to the mutation spectrum of genetic disorders and may be a higher prevalence ofautosomal recessive (AR) disorders in some communities. We observed that in many nonconsanguineous families with rare autosomaldisorders, maternally and paternally inherited mutations are same, indicating common ancestor. In this era of genomic techniques, findinghomozygous regions have become easy. It was seen that the patients with AR disorders, who were homozygous for the disease causingpathogenic / likely pathogenic variations, have large stretches (0.6–188 Mb) of homozygosity around the causative sequence variations.SNP microarray data of patients from consanguineous and nonconsanguineous families also showed that even patients from nonconsanguineousfamilies had 3–49 Mb size regions of homozygosity. Long stretches of homozygosity around homozygous rare pathogenicvariants in nonconsanguineous families with rare AR disorders supports the notion that these couples may have a common ancestor formore than six generations and the system of marriages between same groups. Hence, using the strategy of homozygosity by descent even innonconsanguineous families can be fruitful in identifying the novel pathogenic variations and novel genes.

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