Blood samples were randomly collected on 186 unrelated males coming from all regions of Morocco. DNA was extracted using a Nucleon extraction kit (Amersham Life Science) and was geno-typed with the Powerplex 16 kit (Promega) containing markers D3S1358, TH01, D21S11, D18S51, Penta E, D5S818, D13S317, D7S820, D16S539, CSF1PO, Penta D, vWA, D8S1179, TPOX, and FGA. Profiles were analyzed on a ABI 3100 sequencer (Ap-plied Biosystem, Inc).

A putative tumor suppressor gene involved in B cell chronic lymphocytic leukemia (B-CLL) was mapped to human chromosome 13q14.3 close to the genetic markers D13S25 and D13S319. We constructed a 780-kb-long contig composed of cosmids, bacterial artificial chromosomes, and bacteriophage P1-derived artificial chromosomes that provides essential information and tools for the positional cloning of this gene. The conting contains both flanking markers as well as several additional genetic markers, three ESTs, and one potential CpG island. In addition, using one B-CLL patient, we characterized a small internal deleted region of 550 kb. Comparing this deletion with other recently published deletions narrows the minimally deleted area to less than 100 kb in our physical map. This deletion core region should contain all or part of the disrupted in B cell malignancies tumor suppressor gene.

We describe seven restriction fragment length polymorphisms (RFLPs) in the Leukemia Inhibitory Factor (LIF) gene region. These new markers, found using a cosmid contig, have been used to map precisely the chromosome 22 long arm.