Syndromic thrombocytopenia and predisposition to acute myelogenous leukemia caused by constitutional microdeletions on chromosome 21q.
Several lines of evidence support the presence of dosage-sensitive genes on chromosome 21 that regulate leukemogenesis and hematopoiesis. We report a detailed clinical and molecular characterization of 3 patients with chronic thrombocytopenia caused by distinct constitutional microdeletions involving chromosomal region 21q22.12. The patients exhibited growth restriction, dysmorphic features, and developmental delays. One patient developed acute myelogenous leukemia (AML) at 6 years of age. All 3 deletions included the RUNX1, CLIC6, DSCR, and KCNE1 genes. Our data provide additional support for the role of RUNX1 haploinsufficiency in megakaryopoiesis and predisposition to AML. The leukemic clone had trisomy 21 resulting from duplication of chromosome 21 containing the RUNX1 deletion. This shows that genes other than RUNX1 must also play a role in AML associated with trisomy 21. We recommend that children with syndromic thrombocytopenia have clinical array-comparative genomic hybridization analysis and appropriate cytogenetic studies to facilitate our ability to provide a definitive diagnosis.
Shinawi
Marwan
M
Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA.
Erez
Ayelet
A
Shardy
Deborah L
DL
Lee
Brendan
B
Naeem
Rizwan
R
Weissenberger
George
G
Chinault
A Craig
AC
Cheung
Sau Wai
SW
Plon
Sharon E
SE
D002648:Child; D002872:Chromosome Deletion; D002891:Chromosomes, Human, Pair 21; D002999:Clone Cells; D050676:Core Binding Factor Alpha 2 Subunit / Q000235:genetics; D004920:Erythropoiesis; D020022:Genetic Predisposition to Disease; D006801:Humans; D015470:Leukemia, Myeloid, Acute / Q000175:diagnosis / Q000235:genetics*; D008533:Megakaryocytes; D013577:Syndrome; D013921:Thrombocytopenia / Q000235:genetics*
D050676:Core Binding Factor Alpha 2 Subunit; C493728:RUNX1 protein, human