ABSTRACT INTRODUCTION The consequences of de novo balanced structural chromosome aberrations diagnosed antenatally are unpredictable, and, as a result, they introduce uncertainty into genetic counseling decisions. OBJECTIVE Describe de novo balanced structural aberrations present at antenatal diagnosis in samples from pregnant women in five Latin American countries and determine their effect on carrier individuals. METHODS This was a retrospective observational study based on analysis of 109,011 antenatal tests conducted from January 1981 to December 2016 in Cuba, Uruguay, Costa Rica, Mexico, and Colombia. Thirteen cytogenetic laboratories provided information that included the cases analyzed during the study period; number of de novo balanced structural aberrations diagnosed antenatally; number of diagnoses with de novo balanced structural aberrations that resulted in termination of pregnancy; detailed descriptions of the karyotypes of de novo balanced structural aberration carriers, and descriptions of the form of diagnosis, including types of samples used (amniotic fluid, chorionic villus or fetal blood). Each laboratory also provided pathology reports and genetic counseling at time of diagnosis. Postnatal followup for pregnancies carried to term continued for at least two years. RESULTS Of the 109,011 antenatal tests studied, 72 (0.07%) showed de novo balanced structural aberrations. These events primarily involved chromosomes 1, 2, 7, 14, 18, and 20. Of the 79 breakpoints identified, the most common were 5p15.3, 7q11.2, 7q22, and 14q24. We identified three breakpoints corresponding to 3.8% (3q13.1, 3q13.2, and 9p12) that were not reported in other studies of de novo balanced structural aberrations diagnosed antenatally in patients from other geographic regions or in studies of chromosomal fragile sites. Two of these breakpoints (3q13.1 and 3q13.2) were associated with high risk of phenotypic abnormalities. Information on antenatal or postnatal followup was available for 62 (86%) of de novo balanced structural aberration carriers; of the 44 carriers with postnatal followup, 10 had phenotypic abnormalities. CONCLUSIONS Three new de novo breakpoints were identified, presumably related to genetic admixture characteristics in Latin America. Since some diseases associated with de novo balanced structural aberrations detected antenatally have a late onset, followup for at least two years is recommended for carriers of these aberrations. The information in this study is useful in genetic counseling for pregnant women in Latin America.

Introduction: the Merkel cell carcinoma is a rare cutaneous malignant neoplasm with fast growing and a great metastatic capacity. The Merkel cell carcinoma may be presented in head, neck, arms and legs previously exposures to sun. Clinical and Histological can be differentiated from sudoriparous gland, small cell carcinoma, melanoma and in general other cutaneous diseases. Objective: to describe a Merkel cell carcinoma case and show it to the scientific community. Case presentation: we present a female patient, white, 89 years old, with healthy antecedents coming to our outpatient consult due to neoplastic lesion in the right nasal wing of 2.5 Cm diameter and three month evolution. It was decided to perform a previously biopsy because the lesion observed characteristics with post surgery satisfactory evolution. Conclusions: the Merkel cell carcinoma is an aggressive and low frequently disease, The histopathology and immune- histochemical study confirmed the presumptive diagnosis.

Introducción: el Carcinoma de Células de Merkel es una neoplasia cutánea, maligna, poco frecuente, de rápido crecimiento y con gran capacidad metastizante. Se presenta en la cabeza, cuello, brazos, y piernas que han estado expuestos al sol. Se puede diferenciar clínica e histológicamente de los carcinomas de las glándulas sudoríparas, carcinoma de células pequeñas, melanoma y en general de lesiones cutáneas. Objetivo: describir un caso de Carcinoma de Células de Merkel y exponerlo ante la comunidad científica. Presentación del caso. paciente femenina de 89 años, con antecedentes de salud, quien acude a consulta por una lesión neoplásica en el ala derecha de la nariz de 2,5 cm de diámetro y 3 meses de evolución. Se decidió hacer biopsia previa por las características visibles que presentaba la lesión, con evolución postoperatoria satisfactoria. Conclusiones: el Carcinoma de Células de Merkel es una enfermedad poco frecuente, agresiva. Al examen histopatológico e inmunohistoquímico se corrobora el diagnóstico presuntivo.