18q-mosaicism associated with Rett syndrome phenotype.

Rett syndrome consists of a characteristic progressive encephalopathy in females. The cause of this syndrome is unknown. We present a patient with 18q-mosaicism who, along with the characteristics of this autosomal deletion, also fulfills the clinical criteria for Rett syndrome.

Canadian multicenter randomized clinical trial of chorion villus sampling and amniocentesis. chromosome mosaicism in CVS and amniocentesis samples.

Data on 1040 chorionic villus and 969 amniotic fluid samples were collected from women studied in the Canadian Multicentre Randomized Clinical Trial of Chorion Villus Sampling and Amniocentesis. Cytogenetic results were obtained from 98.0 per cent of chorionic villus samples and from 99.

Gene expression and metastasis of somatic cell hybrids between murine fibroblast cell lines of different malignant potential.

We have used somatic cell hybrids to study the relationship between ras sensitivity, metastasis, and the expression of ras-responsive or "metastasis-associated" genes. We have previously shown that NIH 3T3 cells are nontumorigenic, but are made metastatic by transfection and expression of activated ras (i.e.

Anterior segment mesenchymal dysgenesis associated with partial duplication of the short arm of chromosome 2.

We present a case of partial duplication of the short arm of chromosome 2 (karyotype 46,XX, dup [2p21-2p25]) in a newborn girl. The infant was born at 41 weeks of gestation and died approximately 3 hours after birth. At autopsy the characteristic dysmorphic features (hypertelorism, high, prominent forehead, micrognathia and low-set, malformed ears) and numerous other congenital malformations were observed.

Choroideremia associated with an X-autosomal translocation.

A patient with mild choroideremia has been shown to carry a balanced translocation between chromosome X and 13-46,X,t(X;13)(q21.2;p12). Loci (DXY21, DX232, DX233) shown to map to this region on the X chromosome and in some cases to be deleted in other patients with choroideremia are intact in the DNA from this patient.

Human ETS2 gene on chromosome 21 is not rearranged in Alzheimer disease.

The human ETS2 gene, a member of the ETS gene family, with sequence homology with the retroviral ets sequence of the avian erythroblastosis retrovirus E26 is located on chromosome 21. Molecular genetic analysis of Down syndrome (DS) patients with partial trisomy 21 allowed us to reinforce the supposition that ETS2 may be a gene of the minimal DS genetic region. It was originally proposed that a duplication of a portion of the DS region represents the genetic basis of Alzheimer disease, a condition associated also with DS.

The use of testicular volume as a clinical marker for cytogenetic disorders in mentally retarded males.

The testicular volumes (V) of 817 adult (non-Down's syndrome) institutionalized males were calculated. The mean testicular volume was 19.5 +/- 15.

Prenatal diagnosis of 45,X/46,XY mosaicism in a fetus with asymmetric gonadal dysgenesis.

An 18 week abortus had been prenatally diagnosed as a 45,X/46,XY mosaic. The fetus was a phenotypic male with glandular hypospadias, a horseshoe kidney and asymmetric gonadal dysgenesis. This case represents a rare instance of prenatally diagnosed 45,X/46,XY mosaicism with an abnormal phenotype.

Supernumary marker chromosomes in a mentally retarded population identified as inv dup(15).

Bisattelited supernumary chromosomes, identified as inv dup(15)s, were detected at a prevalence of 8/1000 among institutionalized, mentally retarded (non-Down syndrome) males. This finding suggests that the inv dup(15) contributes significantly to the etiology of mental retardation among institutionalized individuals.

Trisomy 22 mosaicism syndrome and Ullrich-Turner stigmata.

Mosaic trisomy 22, ascertained in three unrelated patients, was found to be associated with body asymmetry and signs of the Ullrich-Turner syndrome including short stature, ptosis, webbed neck, nevi, cubitus valgus, dysplastic nails, malformed great vessels, and abnormal ovaries. These anomalies in trisomy 22 mosaicism have not been emphasized heretofore. In each of our patients, trisomy 22 mosaicism was found only in fibroblasts.

Trisomy no. 15 in murine thymomas induced by chemical carcinogens, X-irradiation, and an endogenous murine leukemia virus.

Chromosome banding techniques were used to examine the karyotype of tumor cells from thymic lymphomas induced by three different carcinogens (X-irradiation, polycyclic aromatic hydrocarbons, and an endogenous leukemogenic virus) after injection into neonatal mice of 2 different inbred mouse strains (CFW/D and C57BL/Ka). A total of 89 tumors were studied, and of these 85.4% were characterized by a modal chromosome number of 41.

The clinical syndrome of triploidy.

The clinical syndrome associated with triploidy is quite typical but is rarely reported in near-term stillborns and newborns. The occurrence of a large placenta with areas of hydatidiform changes in combination with an edematous fetus with macroglossia, facial clefts, eye defects, dysplastic cranial bones, omphalocele, meningomyelocele, syndactyly, and, in males, genital maldevelopment is suggestive of a triploid chromosomal constitution.

Cytogenetic practice in a mental retardation clinic.

Chromosome abnormalities are known to be associated with a wide variety of psychiatric disorders varying from severe mental retardation to aberrant social behaviour. Principles and methods used in contemporary cytogenetic laboratories are discussed and an attempt is made to illustrate how the integration of these techniques can be of considerable value for diagnostic and genetic counselling purposes.