Genetics of the ST serotype system in Tetrahymena pyriformis, syngen 1.

Genetic analyses using lines of Tetrahymena pyroformis manifesting different serotypes indicate that the St serotypes are governed by alleles at a single genetic locus. These alleles are termed St(A) and St(C). The St locus is not closely linked to any of the other well-studied loci examined. Differentiation in St(A)/St(C) heterozygotes follows a pattern very similar to that observed with lines heterozygous at the other loci. Initially both alleles are expressed, but as the synclone divides, lines develop that manifest one allele or the other but not both. The time of differentiation is very early in the clonal life cycle, and the output ratio is eccentric. The pattern of development of the St locus places it in a category with the mating type and H serotype loci.

An association of prune belly anomaly with trisomy 21.

We report on two patients with prune belly anomaly (PBA) and trisomy 21 documented by clinical examination and cytogenetic investigation. The first infant was diagnosed at birth. A distended bladder was detected prenatally by ultrasound in the second patient, and chromosome studies were performed on cells obtained from fetal "bladdercentesis." We discuss the importance of cytogenetic studies in cases where fatal surgery is a consideration.

Duplication of distal 19q: clinical report and review.

We report on a 20-month-old boy with duplication of the distal part of 19q. His karyotype is 46,XY, -22, + der(22),t(19;22)(q13.3;p11.2)mat. The propositus has multiple minor anomalies, congenital heart defects, seizures, profound psychomotor retardation, and growth impairment. These characteristics are similar to those in the other 10 reported cases of distal 19q duplication and help delineate the phenotype. A review of the literature is presented.

Tetrasomy 9p: tissue-limited idic(9p) in a child with mild manifestations and a normal CVS result. Report and review.

Supernumerary isochromosomes resulting in autosomal tetrasomy are rare and have been described only for 12p, 18p, and 9p. Nineteen previous cases of tetrasomy 9p have been reported, and in 6 cases, tissue-specific mosaicism was implied with the i(9p) cell line present exclusively or predominantly in blood. We report on an infant who had apparently normal chromosomes (46,XY) on CVS. He was referred for genetic evaluation because of mild developmental delay and minor anomalies. In 75% of blood cells he had an extra isodicentric 9p chromosome (pter-->q12-->pter). The interpretation of tetrasomy 9p was confirmed by elevated GALT activity. No tetrasomy 9p cells were seen in 100 skin fibroblasts. This case demonstrates the tissue specific mosaicism in tetrasomy 9p which rendered the anomaly undetectable by CVS. It also demonstrates the mild end of the clinical spectrum associated with tetrasomy 9p.

Novel ring chromosome composed of X- and Y-derived material in a girl with manifestations of Ullrich-Turner syndrome.

We present a female infant who has a novel genetic variant of Ullrich-Turner syndrome. Chromosome analysis on amniotic fluid cells obtained because of ultrasound observation of nuchal thickening showed 45,X in all cells. The infant was born with a low posterior hairline and moderate edema over hands and feet. Postnatal chromosome analysis demonstrated two cell lines-47% of the metaphases were 45,X, but 53% had a ring chromosome in addition to the normal X. FISH studies using alpha satellite probes, an X-whole-chromosome-paint (WCP) probe, and a Y-cocktail probe determined that the ring was composed of both X and Y sequences. FISH studies also determined that the KAL locus was present on the ring, but that XIST was absent. PCR-based analysis of lymphocyte DNA documented that the ring contained sequences from both the short and the long arm of the Y chromosome. X-chromosome analysis using a panel of highly polymorphic markers indicated that the ring contained material derived only from Xp22.1 to Xp21.3. No Xq material was identified on the ring, and androgen receptor-based X-inactivation studies suggested that the intact X chromosome was not subject to random X inactivation.

Antenatal diagnosis of a de novo paracentric inversion of chromosome 11.

A de novo paracentric inversion of chromosome 11 identified through antenatal diagnosis is described along with long-term follow-up information on the child and discussion of reported experiences with de novo inversions.

Gonadal dysgenesis, intra-X chromosome insertion, and possible position effect in an otherwise normal female.

A 16-year-old female was referred for cytogenetic evaluation because of primary amenorrhea. Growth, mental development, and physical examination, including secondary sexual characteristics, were normal. Cytogenetic analysis revealed one X chromosome to be consistently more metacentric than the other. Measurements indicted no significant differences between the two X's, but in the abnormal X, the increase in length of the short arm matched the decrease in length of the long arm. Banding studies suggest that region q22 through q24 of the abnormal X is inserted into region p11 of the same chromosome. Endocrine studies were indicative of gonadal dysgenesis. Since no loss of X chromosome material is involved, this patient's gonadal dysgenesis is most likely related to position effect.

Trisomy 21 mosaicism in two successive generations in a family.

The occurrence of 46,XX/47,XX,+21 mosaicism in two successive generations implies an aetiological relationship between the 47,XX,+21 cell line of the mother and her daughter.

Baboon/human homologies examined by spectral karyotyping (SKY): a visual comparison.

Baboon (Papio hamadryas) metaphase chromosomes were analyzed using spectral karyotyping (SKY), a technique combining fluorescence microscopy, CCD-imaging, and Fourier spectroscopy. Results from a comparison of SKY analyses using probes derived from human chromosomes on baboon metaphases were consistent with the majority of comparative gene mapping data between the two species. These data were also compatible with earlier studies comparing macaque and human chromosomes. Human (HSA) chromosome 2 was homologous to baboon (PHA) chromosomes 12 (HSA 2q) and 13 (HSA 2p), whereas three baboon chromosomes corresponded to two different human chromosomes: PHA 3 to HSA 7 and HSA 21, PHA 7 to HSA 14 and HSA 15, and PHA 10 to HSA 20 and HSA 22. These results support the retained synteny between the Hominidae and Cercopithecidae genomes.