Progressive Pseudorheumatoid Dysplasia of Childhood (PPRD)-A Case Series with Recurrent c.740_741del Variant.

Progressive pseudorheumatoid dysplasia (PPRD) is an autosomal recessive arthropathy, affecting school-aged children. It is characterized by progressive degeneration of the articular cartilage. The majority of the pathogenic variations are found in exon 2, exon 4, and exon 5 of the putative gene, CCN6 (WISP3). Three unrelated individuals with clinical diagnosis of PPD were included in this study. Detailed clinicoradiological evaluation was attempted with brief literature review. Exome sequencing was performed in all three cases. All the pathogenic variations detected in our cohort were located in exons 2 and 4 of WISP3 gene. Though the clinicoradiological features are already well described, this study in north India highlights the occurrence of a recurring pathogenic variant. The c.740_741del variant was a recurrent pathogenic variant seen in all three patients in this cohort. This may be a common pathogenic variant in the North Indian population; however, a larger cohort needs to be studied before drawing final conclusions. A proper molecular diagnosis is a must to end the diagnostic odyssey, safeguarding patients with PPRD from unnecessary use of drugs like corticosteroids.

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

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.