RESUMEN
Beginning with a patient presenting with an atrial septal defect (ASD) of the secundum type, the genealogy was identified in four affected individuals who belonged to three successive generations of the same family. The defects were visually confirmed in all individuals and were found to be anatomically similar. No other congenital malformations were present in these individuals. The genealogy was identified in 1972, when ASD recurred in two generations, and it was concluded that the mechanism of transmission was autosomal recessive. The fifth individual, identified 21 years later, and having an anomaly identical to that of the others, was the child of a couple who had no consaguinity and whose mother was a member of the previously studied genealogy. Considering the absence of phenotype in the parents and the rarity of the ASD gene in the general population, the occurrence of the uniparental disomy for this family nucleus, and the same autosomal recessive mechanism of transmission by this affected individual is possible. This study reports the familial occurrence of ASD by genetic mechanisms of transmission, emphasizing the necessity for genetic-clinical studies in members of the familial nucleus in order to detect new carriers, who usually are asymptomatic, thereby allowing for early and adequate treatment of individuals who may be affected.
Asunto(s)
Defectos del Tabique Interatrial/genética , Femenino , Humanos , Masculino , LinajeRESUMEN
One t(14q14q), three t(15q15q), two t(21q21q), and two t(22q22q) nonmosaic, apparently balanced, de novo Robertsonian translocation cases were investigated with polymorphic markers to establish the origin of the translocated chromosomes. Four cases had results indicative of an isochromosome: one t(14q14q) case with mild mental retardation and maternal uniparental disomy (UPD) for chromosome 14, one t(15q15q) case with the Prader-Willi syndrome and UPD(15), a phenotypically normal carrier of t(22q22q) with maternal UPD(22), and a phenotypically normal t(21q21q) case of paternal UPD(21). All UPD cases showed complete homozygosity throughout the involved chromosome, which is supportive of a postmeiotic origin. In the remaining four cases, maternal and paternal inheritance of the involved chromosome was found, which unambiguously implies a somatic origin. One t(15q15q) female had a child with a ring chromosome 15, which was also of probable postmeiotic origin as recombination between grandparental haplotypes had occurred prior to ring formation. UPD might be expected to result from de novo Robertsonian translocations of meiotic origin; however, all de novo homologous translocation cases, so far reported, with UPD of chromosomes 14, 15, 21, or 22 have been isochromosomes. These data provide the first direct evidence that nonmosaic Robertsonian translocations, as well as isochromosomes, are commonly the result of a mitotic exchange.
Asunto(s)
Translocación Genética , Aneuploidia , Cromosomas Humanos Par 13 , Cromosomas Humanos Par 14 , Cromosomas Humanos Par 21 , Cromosomas Humanos Par 22 , Femenino , Tamización de Portadores Genéticos , Humanos , Masculino , Linaje , Cromosomas en AnilloRESUMEN
We report on a girl with cleft lip and cleft palate, antimongoloid slant of the palpebral fissures, umbilical hernia, skeletal anomalies, partial syndactyly, hypertonia with increased deep tendon reflexes, psychomotor and growth retardation, and other congenital anomalies. Cytogenetic studies demonstrated a 46,XX,del(6)(qter----p23:) chromosome constitution.
Asunto(s)
Anomalías Múltiples/genética , Deleción Cromosómica , Cromosomas Humanos Par 6 , Bandeo Cromosómico , Labio Leporino/genética , Fisura del Paladar/genética , Huesos Faciales/anomalías , Femenino , Humanos , Recién Nacido , Discapacidad Intelectual/genética , Reflejo de Estiramiento , Columna Vertebral/anomalíasRESUMEN
The authors report a case of genetic counseling to a family in which a balanced translocation was identified in the father of a malformed child who died without a cytogenetic study being performed. The patient's wife became pregnant again and was submitted to prenatal diagnostic procedures. The result showed a normal female karyotype and a normal girl was delivered at term.
Asunto(s)
Asesoramiento Genético , Cariotipificación , Translocación Genética/genética , Amniocentesis , Femenino , Humanos , Recién Nacido , Masculino , LinajeRESUMEN
A family with four 46,XX siblings affected by the pure gonadal dysgenesis syndrome is described. Inheritance is by an autosomal recessive gene limited to the female sex.