Masao S. Sasaki

A further survey of the chromosomes in the Japanese.

SummaryIn the present study, information was obtained on the chromosomes in somatic cells derived from various organs of 135 foetuses, 1 to 7 months of age, and in germ-cells of two adult males.The chromosome counts were carried out on 2633 cells in primary cultures, on 3933 cells in subcultures and on 30 cells from directly squashed organs.In this total of 6596 cells studied, 6344 cells, or 96.18 per cent contained the normal complement of 46 chromosomes, regardless of sex, age, organ or experimental procedure. No evidence was detected for a chromosomal polymorphism in either somatic or germ-cells.In primary cultures from 127 foetuses two chromosomally abnormal individuals have been found. One contained in the majority of cells studied an obnormal complement of 45 chromosomes, a new, unusual karyotype of XY sex-chromosome constitution. The other showed cells with chromosome aberrations involving chromosome breaks, translocations and fragments in relatively high frequency.The sex-ratio (100 × N♂♂/N♀♀), observed on the basis of chromosomal diagnosis, was 96.67.

A long Y chromosome in man

SummaryAn unusually long Y chromosome was described in the phenotypically normal father and paternal grandfather of a girl with Downs syndrome, and likewise in a male infant with multiple malformations and his father, normal in phenotype. Measurements revealed that the long Y chromosome corresponded in length to autosomes of group 16–18.Information was obtained to show that the increased length of the Y chromosome was an inheritable character, and that a long Y chromosome was not always associated with an abnormal phenotype (or phenotypes).