Deletion of the short arm of chromosome No. 10

A newborn male infant, whose karyotype was 46,XY,del(10)(p13) is presented. The clinical features included cleft lip and palate, preauricular pits, low set malpositioned auricles, antimongoloid slant of the eyes, microcephaly, micrognathia, congenital heart disease, hypertrophic pyloric stenosis, cryptorchidism, and abnormal dermatoglyphics. The child died at the age of 3 months in overwhelming urinary infection with septicemic complications. It is suggested that the features described here may represent a new, clinically recognizable chromosomal syndrome.

Familial mental retardation in a family with an inherited chromosome rearrangement

A family of three generations has been described with an insertional type of chromosome rearrangement involving chromosomes 11 and 18[46,XX or XY, ins(11;18)(p15;q11q21)] detected by G-banding using a trypsin digestion method. Four members of this family with clinical features of 18q− have inherited the der(18) from their father and are thus deficient for (18)(q11q21). Three other family members have inherited the der(11) and thus have a duplication of the same segment [(18)(q11q21)]. Genetic marker studies on this family, show no significant segregation of any of the markers studied with either the der(11) or der(18). Eight family members had the PepA⁸PepA¹ genotype and four of these were carrying the der(18), indicating that the PepA locus which had been previously assigned to chromosome 18, does not lie in the segment q11→q21.

A 48, XXXX female

A four-year-old mildly retarded girl with a 48,XXXX karyotype is described. Her phenotype is compared to previously reported cases.

Constitutive heterochromatin in mouse chromosomes treated with typsin

Chromosome preparations from three sublines of mouse L-cells (A9, B82 L60) were made by conventional air-drying methods and the slides treated both by trypsin digestion and the C-banding methods, in order to investigate and compare the distribution of constitutive heterochromatin in these cells. Comparisons were also made with human and Chinese hamster cells. The mouse heterochromatic sites observed, including the interstitial sites found on the marker chromosomes, were similar for each line irrespective of the method used. The interstitial heterochromatic sites in the marker chromosomes 1 and 3 correspond to the locations of the secondary constrictions. The trypsin digestion method reveals the sites of constitutive heterochromatin in mouse chromosomes, but not in human or Chinese hamster chromosomes. All mouse chromosomes could be distinguished from those of Chinese hamster in the hybrid cells between mouse and Chinese hamster cell lines. The method is simple to use and therefore will facilitate the identification of mouse chromosomes within and between the cell populations of different origins and within cell hybrids.

Chromosome studies in a neonatal population

The results of chromosome studies on 6809 consecutive newborn infants are presented. One hundred and one (1.48%) were heterozygous for a marker chromosome, the significance of which is not at present clear. Twenty-two infants (0.32%) had a major chromosome abnormality. Only six of these infants (0.09%) had a clinically recognizable abnormal phenotype (Down's syndrome). The occult chromosome abnormalities included five sex chromosome abnormalities (one 47,XYY; two 47,XXY; two 47,XXX) and 11 balanced translocations. Seven of these were t(DqDq) and four were reciprocal translocations. The results of the present survey are combined with four other similar neonatal surveys in which a total of 23,328 newborns have been screened. Of these, 117 (0.5%; range 0.65-0.32%) had major chromosome abnormalities. The majority of these (72.7%) would not have been detected at birth without chromosome studies, an important fact in the context of prenatal diagnosis of chromosome disease and the early ascertainment of high-risk families.

Conenital hypothyroidism in association with a ring chromosome 18

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In vitro leucocyte cultures of Syrian and Chinese hamsters

An investigation of a variety of different separation procedures and culture conditions was made in order to evaluate the methods for culturing leucocytes in vitro of Syrian and Chinese hamsters. Dextran (6%), human AB serum and fetal calf serum (FCS) were used as separating agents. In the Chinese hamster the best results were obtained with AB serum whereas in the Syrian hamster adequate separation was obtained with all three agents. Supplementation of the culture medium with FCS provided the most favourable conditions for cell survival in culture. Maximal numbers of mitoses were obtained after 4 days of culture at 37 °C with the Syrian hamster (0.5%) and after 5 days with Chinese hamster (0.2%). Leucocytes of Syrian and Chinese hamsters were also cultured following immunization with each of the ABO sera as well as with FCS. Both macro- and micromethods were partially successful. Using the macromethod, no mitoses were observed in the Chinese hamster, but a few in Syrian hamsters immunized with B serum. With the micromethod, mitotic figures were observed in Syrian hamsters immunized with B serum, O serum and FCS, and Chinese hamsters with O serum and FCS. Leucocytes of the Chinese hamster proved difficult to culture successfully by any of the methods used, whereas, with the Syrian hamster, immunization with FCS and culture using micromethod gave the best results.

Evaluation of cell viability in chromosomally heterogeneous cell populations

A method is described for determining cell viability in chromosomally heterogeneous cell populations. Individual cells were plated out to obtain clonal growth and the clones processed for chromosomes in situ. The majority of cell types in each of the parental populations examined were represented amongst the clones arising from that population.