COASY related pontocerebellar hypoplasia type 12: A common Indian mutation with expansion of the phenotypic spectrum.

Pontocerebellar hypoplasia (PCH) type 12 is a rare, perinatal lethal neurodegenerative genetic disorder caused by biallelic mutations in the COASY gene. Herein, we describe the clinical and neuroradiological profile of nine affected fetuses/neonates from five families identified with a common COASY: c.1486-3C>G biallelic variant. Four of the five families were identified after data reanalysis of unresolved, severe PCH like phenotype and the fifth family through collaboration. The common antenatal phenotype was cerebellar hypoplasia. Microcephaly, arthrogryposis, and intrauterine growth restriction were the shared postnatal findings. The neurological manifestations included seizures, poor sucking, and spasticity. Novel findings of corpus callosum agenesis, simplified gyral pattern, normal sized pons, optic neuropathy, and a small thorax are reported in this series. The allele frequency of the COASY: c.1486-3C>G variant was 0.62% in the available Asian Indian database. We describe this as a possible common Indian origin variant. To the best of our knowledge, this is the largest PCH12 series reported.

The fatal fetal tumor: a geneticist's perspective.

Epignathus is an extremely rare oral teratoma which leads to high mortality in the early neonatal period. Various theories have been put forward for the genesis of such a tumor, though none is completely convincing. A genetic basis is not well established for the tumor. Microdeletions/duplications, as well as single gene disorders, have been known to cause epignathus, all with additional malformations. Evidence of single gene involvement in an isolated epignathus is lacking. We present a case of a 19-week-fetus with oro-pharyngeal teratoma detected on the level II ultrasound. The couple was counseled regarding the grave prognosis of the fetal condition following which they opted for termination of pregnancy and fetal autopsy. The autopsy revealed fetus-like body attached to the tumor. Genetic testing including a whole genome microarray did not reveal any significant variant. An explanation for the fetus-like body maybe a common origin of the teratoma and the additional fetus-like bodies due to an erroneous process of early embryonic development. Another possibility is of an acardiacus acranius twin masquerading as a fetus-like body. Thus, we conclude that in the absence of an associated malformation, an epignathus is unlikely to have a genetic etiology. This study highlights the importance of performing a fetal autopsy as a part of deep phenotyping to ascertain the etiology, as it identified additional fetal-like body which was not detected on the antenatal ultrasound.

Robinow Syndrome and Brachydactyly: An Interplay of High-Throughput Sequencing and Deep Phenotyping in a Kindred.

We report a family with a spectrum of short stature, craniofacial dysmorphism, and digital anomalies in a father and 2 daughters, with the youngest (proband) displaying a severe phenotype. Clinically, autosomal dominant Robinow syndrome (ADRS) was diagnosed. Whole-exome sequencing identified a heterozygous pathogenic BMP2 variant in the father and his daughters. The phenotype of short stature, facial dysmorphism, and skeletal anomalies with or without cardiac anomalies related to BMP2 haploinsufficiency has some facial and digital resemblance to ADRS. Although this variant segregated in the affected members, it failed to explain the severe phenotype of the proband. A reanalysis of the girl's raw data confirmed 2 disorders: a de novo likely pathogenic DVL1 variant implicated in ADRS and the familial BMP2 variant. A close interplay of high-throughput sequencing and deep phenotyping unraveled the complexities of the blended phenotype in the proband.