María Paz Bidondo1,2, Boris Groisman1, Agostina Tardivo1, Fabián Tomasoni1,3, Verónica Tejeiro1,3, Inés Camacho1,4, Mariana Vilas1, Rosa Liascovich1, Pablo Barbero1. 1. National Network of Congenital Anomalies of Argentina (RENAC), National Center for Genetic Medicine (CNGM), National Administration of Labs and Health Institutes (ANLIS), Buenos Aires, Argentina. 2. Department of Cellular Biology, Histology, Embryology and Genetics. Medicine College, University of Buenos Aires (UBA), Buenos Aires, Argentina. 3. Neonatology Service in the Evita Pueblo Hospital, Buenos Aires, Argentina. 4. Neonatology Service in the 25 de Mayo Hospital, Catamarca, Argentina.
Abstract
BACKGROUND: Diprosopus is a subtype of symmetric conjoined twins with one head, facial duplication and a single trunk. Diprosopus is a very rare congenital anomaly. METHODS: This is a systematic review of published cases and the presentation of two new cases born in Argentina. We estimated the prevalence of conjoined twins and diprosopus using data from the National Network of Congenital Anomalies of Argentina (RENAC). RESULTS: The prevalence of conjoined twins in RENAC was 19 per 1,000,000 births (95% confidence interval, 12-29). Diprosopus prevalence was 2 per 1,000,000 births (95% confidence interval, 0.2-6.8). In the systematic review, we identified 31 diprosopus cases. The facial structures more frequently duplicated were nose and eyes. Most frequent associated anomalies were: anencephaly, duplication of cerebral hemispheres, craniorachischisis, oral clefts, spinal abnormalities, congenital heart defects, diaphragmatic hernia, thoracic and/or abdominal visceral laterality anomalies. One of the RENAC cases and three cases from the literature had another discordant nonmalformed twin. CONCLUSION: The conjoined twins prevalence was similar to other studies. The prevalence of diprosopus was higher. The etiology is still unknown. The presence of visceral laterality anomalies may indicate the link between diprosopus and the alteration or duplication of the primitive node in the perigastrulation period (12-15 days postfertilization). Pregnancies of more than two embryos may be a risk factor for diprosopus. Given the low prevalence of this defect, it would be useful to perform studies involving several surveillance systems and international consortiums. Birth Defects Research (Part A), 2016.
BACKGROUND: Diprosopus is a subtype of symmetric conjoined twins with one head, facial duplication and a single trunk. Diprosopus is a very rare congenital anomaly. METHODS: This is a systematic review of published cases and the presentation of two new cases born in Argentina. We estimated the prevalence of conjoined twins and diprosopus using data from the National Network of Congenital Anomalies of Argentina (RENAC). RESULTS: The prevalence of conjoined twins in RENAC was 19 per 1,000,000 births (95% confidence interval, 12-29). Diprosopus prevalence was 2 per 1,000,000 births (95% confidence interval, 0.2-6.8). In the systematic review, we identified 31 diprosopus cases. The facial structures more frequently duplicated were nose and eyes. Most frequent associated anomalies were: anencephaly, duplication of cerebral hemispheres, craniorachischisis, oral clefts, spinal abnormalities, congenital heart defects, diaphragmatic hernia, thoracic and/or abdominal visceral laterality anomalies. One of the RENAC cases and three cases from the literature had another discordant nonmalformed twin. CONCLUSION: The conjoined twins prevalence was similar to other studies. The prevalence of diprosopus was higher. The etiology is still unknown. The presence of visceral laterality anomalies may indicate the link between diprosopus and the alteration or duplication of the primitive node in the perigastrulation period (12-15 days postfertilization). Pregnancies of more than two embryos may be a risk factor for diprosopus. Given the low prevalence of this defect, it would be useful to perform studies involving several surveillance systems and international consortiums. Birth Defects Research (Part A), 2016.