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.
Multiple family enchondromatosis was described by Virchow in 1910, is presented with a pattern of autosomal dominant inheritance. The enchondromatosis comprise a heterogeneous group of congenital syndromes characterized by the presence of multiple enchondromas associated with musculoskeletal deformities secondary to shortening of the limbs. A family with four members affected, whose diagnosis was made by the clinical method through physical examination and imaging was presented. It is important to made an early diagnosis of this disease because of the possibility of a secondary prevention in patients as well as to provide appropriate genetic counseling to the family.
La encondromatosis múltiple familiar fue descrita por Virchow en 1910, se presenta con un patrón de herencia autosómico dominante. Las encondromatosis comprenden un grupo heterogéneo de síndromes congénitos caracterizados por la presencia de encondromas múltiples, asociados a malformaciones músculos esqueléticos secundarios al acortamiento de las extremidades. Se presentó una familia con cuatro afectados, a los que se les realizó diagnóstico donde se aplicó el método clínico a través del examen físico e imagenológico. Es importante la realización de un diagnóstico precoz de esta entidad por la posibilidad de realizar una prevención secundaria en los pacientes, así como para brindar un adecuado asesoramiento genético a la familia.