Extreme variant of enlarged heterochromatin region on chromosome 9Q in a normal child and multiple family members.

Heteromorphisms of chromosome 9 are among the most common variations in the human karyotype. The pericentromeric polymorphisms of chromosome 9 include variations in the size of q-arm heterochromatin, pericentric inversions, and rarely, additional C-band-negative, G-band-positive material. The finding of a polymorphic variant, either in prenatal screening or in chromosomal analysis for phenotypic abnormalities, may cause parental anxiety and initiate genetic counselling.

A case study of "disorganized development" and its possible relevance to genetic determinants of aging.

In 1932, Bidder postulated that senescence results from "continued action of a (genetic) regulator (of development) after growth ceases (maturation occurs)." A 16-year-old girl who physically appears to be an infant has not been diagnosed with any known genetic syndrome or chromosomal abnormality. The subject's anthropometric measurements are that of an 11-month-old.

Specific extra chromosomes occur in a modal number dependent pattern in pediatric acute lymphoblastic leukemia.

Children with acute lymphoblastic leukemia (ALL) and high hyperdiploidy (>50 chromosomes) are considered to have a relatively good prognosis. The specific extra chromosomes are not random; extra copies of some chromosomes occur more frequently than those of others. We examined the extra chromosomes present in high hyperdiploid ALL to determine if there were a relation of the specific extra chromosomes and modal number (MN) and if the extra chromosomes present could differentiate high hyperdiploid from near-triploid and near-tetraploid cases.

Translocation breakpoint in two unrelated Tourette syndrome cases, within a region previously linked to the disorder.

Tourette syndrome (TS) is a complex neuropsychiatric disorder characterized by both motor and vocal tics. The etiology of TS is poorly understood; however, evidence of genetic transmission arises from family and twin studies. A complex mode of inheritance has been suggested, likely involving contributions of several genes with different effect size.

Hepatosplenic gamma/delta T-cell lymphoma with isochromosome 7q, translocation t(7;21), and tetrasomy 8 in a 9-year-old girl.

The authors report a child younger than age 15 years with a rare hepatosplenic gamma/delta T-cell lymphoma, which is highly aggressive and primarily seen in young men. A 9-year-old girl presented with thrombocytopenia and hepatosplenomegaly. Bone marrow analysis revealed a metastatic pleomorphic lymphoma of peripheral T-cell phenotype, with rearrangement of the T-cell receptor gamma/delta and expression of CD3 and CD16/56.