Significance of chromosome 17ps+ in three generations of a family

Prenatal diagnosis of a trisomy 17p derived from a de novo non-mosaic satellited marker

A trisomy 17pter --> p11.2 derived from a supernumerary de novo satellited marker was identified by GTG bands and fluorescent in situ hybridisation (FISH) in amniocytes of a fetus with malformations and intrauterine growth retardation (IUGR). At 39 weeks a male infant with a phenotype similar to other postnatal cases of 'pure' complete trisomy 17p was born. Some additional clinical features, however, make him more severely affected than previous patients.

Nature of distamycin A-inducible fragile sites

Five rare distamycin A-inducible fragile sites have been identified on human chromosomes: fra(8)(q24.1), fra(11)(p15.1), fra(16)(p12.1), fra(16)(q22), and fra(17)(p12). All of these fragile sites are located at the junction of Giemsa-positive (G) and negative (R) bands and their expression can be induced by a variety of AT specific DNA ligands. Analysis of family data indicate that the distamycin A-inducible fragile sites segregate as a simple codominant trait with complete penetrance, and probands receive these fragile site genes equally from mothers and fathers. Based on current knowledge of chromosome instability, the nature of distamycin A-inducible fragile sites is discussed. Distamycin A-inducible fragile sites appear to be unique chromosomal regions particularly susceptible to fragility under certain stress conditions. They may also be hot spots for recombination, gene amplification, and integration of foreign genomes.

Parental trisomy 21 mosaicism

A family with three children with trisomy 21 in which the mother is a phenotypically normal, trisomy 21/normal mosaic was studied. Chromosome 21 fluorescent heteromorphisms were used to document that two of the three number 21's in two of the Down syndrome offspring were of maternal origin. Five cytogenetic surveys in which both parents of a child with trisomy 21 were studied have been reviewed. From these data, it is estimated that 3% of couples producing a child with trisomy 21 can be explained by parental mosaicism. From 17 informative sibships, with one parent mosaic, the segregation ratio was estimated to be 0.43 +/- 0.11.

Silver staining and the 17ps chromosome

Lack of silver staining of a variant chromosome 17 and its failure of involvement in satellite association indicate that this variant is a heteromorphism rather than a translocation of satellited material from any other acrocentric chromosome.

Cytochemical analysis on a case of familial 17ps

Chromosome 17ps was identified in the mother and daughter but not the father of a normal family with no history of congenital abnormality. In addition to G-band and Ag-NOR staining, previously used to study this abnormality, we applied N-band and C-band techniques. Our results showed that 17ps has no demonstrable ribosomal cistron or constitutive heterochromatin.

Silver staining studies on the short arm variant of human chromosome 17

The absence of silver grain precipitation on human chromosome 17, consistently observed in four patients displaying the 17p variant, supports the hypothesis that the 17p variant is a structural heteromorphism rather than translocated satellite material.

A variant chromosome 17 in a mother with repeated abortions and a 46, XY/47, XXY Klinefelter son

A female with a satellited chromosome 17 is presented. She had suffered repeated abortions and later gave birth to a 46,XY/47,XXY Klinefelter boy. The significance of the variant chromosome 17 in the etiology of the mother's reproductive failure is discussed. The mental and physical development of her now 8-year-old 46,XY/47,XXY son has been checked regularly since birth. The boy showed a significant deviation in behaviour pattern and development of body habitus already from early infancy.