del(12)(p)

Epidemiology and Etiology:

· AML (5% have rearrangements involving 12p, most often resulting in loss of material)

· del(12)(p)

· macroscopic usually

· add(12)(p) are frequent, considered imbalanced rearrangements

· unbalanced translocations or dicentrics

· ALL (10% have rearrangements involving 12p)

· del(12)(p)

· add(12)(p)

· monosomy 12

· der(12)t(V;12)(V;p)

· dic(V;12)(V;p)

· MDS (3% have unbalanced rearrangements involving 12p)

Common sites:

·

Gross features:

·

Histologic features:

·

Immunophenotype:

Marker:

Sensitivity:

Specificity:

Molecular features:

· AML:

· 12p deletions often interstitial with a minimal deleted region of 1-2 Mb between ETV6 and CDKN1B (KIP1 / P27KIP1)

· Very heterogenous breakpoints

· Pathogenetically important target gene(s) in del(12)(p) has not been identified

Other features:

· AML:

· Prevalence of 12p abnormalities is significantly higher in t(AML than de novo

· Prognosis generally poor (or intermediate according to some)

· ALL:

· usually occurs as part of a more complex karyotype

· sole aberration in less than 20% of cases with an abnormal 12p

· approximately half of patients with an abnormal 12p have a rearranged TEL gene

References:

· Heim S, Mitelman F. Cancer Cytogenetics. 3rd ed. Wiley-Blackwell; 2009.

· Bilhou-Nabera C . 12p abnormalities in myeloid malignancies. Atlas Genet Cytogenet Oncol Haematol. May 1998 .
URL : http://AtlasGeneticsOncology.org/Anomalies/12pmyelo.html