Interim In vitro Dose-Response Curve for the Dicentric Biodosimeter Assay from a Philippine Radiotherapy Facility using a Linear Accelerator

@#Background. Accidental radiation exposure can occur anytime. Biodosimeters help in quantifying the absorbed dose of individuals who are not equipped with personal dosimeters during radiation exposure. The dicentric assay can quantify radiation damage by correlating radiation dose exposure with the frequency of dicentric chromosomes in the peripheral lymphocytes extracted from exposed individuals. Objective. The study aims to present the interim results of the reference dose-response curve for a Philippine radiotherapy facility constructed using a 6MV linear accelerator (ClinacX, Varian). Methods. Samples of peripheral blood from healthy volunteers were irradiated in a customized water phantom of doses 0.10 to 5.0 Gray using a linear accelerator. The irradiated samples were cultured and analyzed following the International Atomic Energy Agency Cytogenetic Dosimetry Protocol (2011) with modifications. Linear-quadratic model curve fitting and further statistical analysis were done using CABAS (Chromosome Aberration Calculation Software Version 2.0) and Dose Estimate (Version 5.2). Interim results of the samples were used to generate these curves. Results. The dose-response curve generated from the preliminary results were comparable to published dose response curves from international cytogenetic laboratories. Conclusion. The generated dose-response calibration curve will be useful for medical triage of the public and radiologic staff accidentally exposed to radiation during medical procedures or in the event of nuclear accidents.

Mixed gonadal dysgenesis with an ovarian germ cell tumor in a Filipino adolescent

We present a case of a 13-year-old Filipino patient with ambiguous genitalia, randomly assigned as female at birth and was subsequently reared as such. Starting at 10 years of age, secondary male sexual characteristics emerged. However, medical consultation was sought only when the patient developed a gradually enlarging and painful abdominal mass. After cytogenetic studies, we are able to identify the case as Disorder of Sex Development, 45,X/46,X,der(Y) mosaicism, mixed gonadal dysgenesis. Further imaging, laparotomy and histopathology, revealed that the abdomino-pelvic mass was from the right ovary, composed of immature teratoma. Ductus deferens and epididymis were also identified within the right ovary. At the time of presentation, the patient was already experiencing gender dysphoria. This report not only highlights the wide spectrum of phenotypes in mixed gonadal dysgenesis, but also stresses the importance of proper gender assignment during the newborn period in patients with disorders of sex development.Key Words: disorder of sexual development, ambiguous genitalia, mixed gonadal dysgenesis, mosaicism, 45,X/46,X,der(Y) karyotype, immature teratoma, gender dysphoria

Tetrasomy 9p syndrome in a Filipino infant

@#Tetrasomy 9p syndrome is a rare chromosomal abnormality syndrome whose most common features include hypertelorism, malformed ears, bulbous nose and microretrognathia. These features present as a result of an additional two copies of the short arm of chromosome 9. Here we present a neonate with characteristic facial features of hypertelorism, downslanted palpebral fissure, bulbous nose, small cupped ears, cleft lip and palate, and downturned corners of the mouth. Clinical features were consistent with the cytogenetic analysis of tetrasomy 9p. In general, clinicians are not as familiar with the features of tetrasomy 9p syndrome as that of more common chromosomal abnormalities like trisomies 13, 18, and 21. Hence, this case re-emphasizes the importance of doing the standard karyotyping for patients presenting with multiple congenital anomalies. Also, this is the first reported case of Tetrasomy 9p syndrome in Filipinos.