Commentary on the decision of the American Board of Medical Genetics and Genomics to create a 24-month specialty of Laboratory Genetics and Genomics.

Genet Med 19 3, 294-296.

Co-occurrence of non-mosaic trisomy 22 and inherited balanced t(4;6)(q33;q23.3) in a liveborn female: case report and review of the literature.

Trisomy 22 is the third most common autosomal trisomy occurring in about 0.4% of all clinically recognized pregnancies. Complete non-mosaic trisomy 22 is extremely rare in live births.

FOXO1-FGFR1 fusion and amplification in a solid variant of alveolar rhabdomyosarcoma.

Rhabdomyosarcoma is the most common pediatric soft tissue malignancy. Two major subtypes, alveolar rhabdomyosarcoma and embryonal rhabdomyosarcoma, constitute 20 and 60% of all cases, respectively. Approximately 80% of alveolar rhabdomyosarcoma carry two signature chromosomal translocations, t(2;13)(q35;q14) resulting in PAX3-FOXO1 fusion, and t(1;13)(p36;q14) resulting in PAX7-FOXO1 fusion.

Improvement of pancytopenia and thrombocytopenia with decreasing mosaicism for isochromosome Xp.

We report the unique association of variable constitutional mosaicism 46,X, i(X)(p10)/46,XX with recurrent thrombocytopenia in a child with failure to thrive and apnea in infancy. Her bone marrow had equal distribution of the normal and abnormal cell lines at diagnosis, at nearly 6 years of age. Improvement of her pancytopenia and thrombocytopenia was concurrent with a decreasing level of mosaicism observed in multiple studies over the next 3 years.

Down syndrome with low hypodiploidy in precursor B-cell acute lymphoblastic leukemia.

We describe the rare finding of a 33-month-old child neonatally diagnosed with Down syndrome, who presented with pre-B acute lymphoblastic leukemia (ALL) with a pretreatment bone marrow karyotype in which a low hypodiploid cell line (38 chromosomes) was identified in 17/19 cells studied. The abnormal cell line retained the extra constitutional chromosome 21. Hypodiploidy (loss of one or more chromosomes) is seen in approximately 5% of all childhood pre-B ALL cases and in approximately 2.

A report of three patients with an interstitial deletion of chromosome 15q24.

Partial monosomy of the q2 region of chromosome 15 has been infrequently reported. Moreover, interstitial deletions involving 15q22-q24 have been described in only nine patients to date. The phenotype of these reported individuals is subject to the extent of the deletion but typically includes altered muscle tone and significant developmental delays.

Translocation (16;18)(p13;q21.3) in follicular lymphoma.

We describe a novel t(16;18)(p13;q21.3) in a male patient with follicular lymphoma. This unique chromosomal rearrangement has never been described in patients with follicular lymphoma.

A dysmorphic newborn infant with a complex rearrangement involving chromosomes 2, 4, and 6 detected by fluorescence in situ hybridization (FISH).

A newborn female infant with multiple congenital anomalies was found to have an unusual and abnormal karyotype. Cytogenetic studies revealed an apparent balanced translocation between chromosome 4q31.3 and chromosome 6q25.

Characterization of a Wilms tumor in a 9-year-old girl with trisomy 18.

This is a report of a trisomy 18 patient who developed Wilms tumor in conjunction with perilobar nephroblastomatosis (NB) at 9 years and 5 months of age. Review of the literature revealed that most patients with trisomy 18 who develop Wilms tumor, do so at a later than expected age for a tumor related to NB, and are females. In this case, no chromosome 11 WT1 mutation was detected by PCR/SSCP analysis, but the tumor had in addition to the trisomy, an isochromosome 7q and loss of heterozygosity at 16q, two mutations that have been linked independently to Wilms tumorigenesis.

Chromosome rearrangement with no apparent gene mutation in familial adenomatous polyposis and hepatocellular neoplasia.

We have identified a constitutional inversion in chromosome 5 associated with familial adenomatous polyposis in three generations of a Mexican family. Two of three siblings developed hepatic neoplasia in infancy. The gene truncation assay failed to demonstrate a truncated protein in the segment harboring the adenomatous polyposis coli (APC) genes.