PubMed · 1965 · 29 citations · 0 references
Life SciencesGeneticsMolecular GeneticsCytogeneticsHuman GeneticsReproductive GeneticsAneuploidyChromosomal AbnormalitiesChromosomal DisordersCongenital AnomaliesCongenital MalformationsGenetic DisordersAge-related AneuploidyKlinefelter Syndrome GeneticsOffspring DevelopmentParental Age At BirthParental Chromosomal AbnormalitiesSex Chromosome AbnormalitiesSex Chromosome AneuploidiesSex Chromosome Nondisjunction
is more common at increased maternal ages. The precise mechanism of the maternal age effect remains to be explained, but current evidence points to an aberrant oogenesis. Chromosomal nondisjunction in meiosis is thought to be responsible for those conditions manifest by various aneuploidies in the affected offspring. The maternal age effect is clearest in mongolism (Penrose, 1934), and is also evident in Klinefelter^ syndrome (FergusonSmith, 1960; Stewart, 1960). It is also possibly present in the triple X syndrome and in some autosomal trisomys, but is not present in Turner's syndrome of XO type (Boyer, 1961). In a number of malformations with normal karyotype, a maternal age effect on incidence has also been demonstrated. These conditions include