ORIGINAL ARTICLES Dosage of Sex Chromosomal Genes in Blood Deposited on Filter Paper for Neonatal Screening of Sex Chromosome Aneuploidy Luis Daniel Campos-Acevedo, Marisol Ibarra-Ramirez, Jose ´ de Jesu ´ s Lugo-Trampe, Michelle de Jesu ´ s Zamudio-Osuna, Iris Torres-Mun ˜ oz, Ma del Roble Velasco-Campos, Luz Rojas-Patlan, Ira ´ m Pablo Rodrı ´guez-Sa ´ nchez, and Laura Elia Martı ´nez-de-Villarreal Aims: In this study, we examined the doses of the stature homeobox (SHOX), vesicle-associated membrane protein 7 (VAMP7), and SRY genes to establish a protocol for using peripheral blood samples deposited on filter paper for the screening of sex chromosome aneuploidy in neonates. We also measured correlations with kar- yotypes to assess this method as a neonatal screening strategy. Materials and Methods: This was an observa- tional, descriptive, comparative blind study. Thirty-two healthy young adults (17 women, 15 men; age, ‡18 years), four patients with known sex chromosome aneuploidy (positive control group), and 1000 healthy new- borns were included. Gene dosages were determined using quantitative real-time polymerase chain reaction (RT- PCR). Values with standard deviations (SDs) of three or more were considered abnormal. Results: Men and women differed in the gene dosage of the SRY gene. Cases with Turner syndrome showed values below 3 SDs for SHOX and VAMP7 genes, and cases with Klinefelter syndrome showed values above 3 SDs for SHOX and VAMP7 genes. Two suspected cases of sex chromosome aneuploidy were diagnosed using our neonatal screening strategy; these cases were confirmed as Turner syndrome and 47,XYY syndrome by karyotyping. Conclusions: Our data establish a basis for the determination of chromosomal sex and neonatal screening of sex chromosome aneuploidy using RT-PCR. Keywords: aneuploidies, sex chromosome, gene dosages Introduction C onstitutional sex chromosome aneuploidies are, together with Down syndrome, the most frequent chro- mosomal abnormalities in humans. In contrast to autosomal imbalances, sex chromosome aneuploidies are often not as- sociated with visible features in newborns. Therefore, only a small percentage of such disorders are detected at birth, for example, 10% for Klinefelter syndrome (Bojesen et al., 2003) and 30–50% for Turner syndrome (Massa et al., 2005; Lee and Conway, 2014). This reduces the opportunity for early inter- ventions that could improve the quality of life of the affected individuals (Radicioni et al., 2010). Neonatal screening is a public health strategy used to identify individuals at risk of developing a disease through measurement of metabolic and genetic markers. Such screening techniques generally involve a heel stick test in which a sample of peripheral blood is obtained and placed on filter paper. The procedure is not considered invasive to the neonate and could be used for early diagnosis of sex chro- mosome aneuploidies since it meets the Wilson and Jungner screening criteria (Wilson and Jungner, 1968). These criteria include that the disease should be an important health problem with a high incidence, should have a well-established and ef- fective medical treatment, and should be detectable through a screening test that is cost effective, easy to perform and in- terpret, accurate, and reliable, with high sensitivity and spec- ificity for a large volume of samples, among other qualities. Although the gold standard for establishing genetic sex is karyotyping, this technique requires taking a venous blood sample, which is neither feasible nor ethical in newborns as a screening test for sex chromosome aneuploidy. McCabe (1991) reported that genomic DNA (gDNA) from blood de- posited on filter paper can be extracted and applied for screening of various diseases. Subsequently, many groups began to work on developing methods to extract and amplify gDNA on filter paper (Caggana et al., 1998; Chaisomchit et al., 2003); however, the currently available extraction Departamento de Gene ´tica, Facultad de Medicina y Hospital Universitario Jose ´ E. Gonza ´lez, Universidad Auto ´noma de Nuevo Leo ´n (UANL), Monterrey, Me ´xico. GENETIC TESTING AND MOLECULAR BIOMARKERS Volume 20, Number 12, 2016 ª Mary Ann Liebert, Inc. Pp. 1–5 DOI: 10.1089/gtmb.2016.0101 1