Page 165 - Essential Haematology

Chapter 11 Haematological malignancy: aetiology and genetics / 151

The haemopoietic malignancies are clonal diseases mopoietic malignancies is largely unknown. As in
that derive from a single cell in the marrow or most diseases it is the combination of genetic back-

peripheral lymphoid tissue that has undergone ground and environmental influence that deter-
genetic alteration (Fig. 11.1 ). In this chapter we mines the risk of developing a malignancy. For
discuss the aetiology and genetic basis of haemato- example, single nucleotide polymorphism (SNP)

logical malignancy and subsequent chapters discuss analysis has identified polymorphisms in germline
the aetiology, diagnosis and management of the genes, some of which code for proteins involved
individual conditions. in B - cell development, that predispose to risk of
B - cell acute lymphoblastic leukaemia (B - ALL) (see

Chapter 17 ). However, in the majority of cases

The i ncidence of h aematological
neither a genetic susceptibility nor an environmen-
n eoplasms
tal agent is apparent.
Cancer is an increasingly important cause of morbid-
ity and mortality with recent improvements in the
prevention and treatment of cardiovascular disease.
Inherited f actors
Nearly 40% of the population will develop cancer in
their lifetime. The majority of cancers are epithelial The incidence of leukaemia is greatly increased in

malignancies. Haematological malignancies repre- some genetic diseases, particularly Down s syn-
’
sent approximately 7% of all malignant disease (Fig. drome (where acute leukaemia occurs with a 20 - to

11.2 ). There are major geographical variations in 30 - fold increased frequency), Bloom ’ s syndrome,
occurrence of the diseases; for example, chronic lym- Fanconi s anaemia, ataxia telangiectasia, neurofi -
’
phocytic leukaemia (CLL) is the most common leu- bromatosis, Klinefelter s syndrome and Wiskott –
’
kaemia in the West but rare in the Far East. Aldrich syndrome. There is also a weak familial

tendency in diseases such as acute myeloid leukae-
The a etiology of h aemopoietic mia (AML), CLL, Hodgkin lymphoma and non -
Hodgkin lymphoma (NHL) although the genes
m alignancy
predisposing to this increased risk are largely
Exactly how genetic mutations accumulate in hae- unknown.

100
% of marrow cell population 50 haemopoietic expansion

Normal
tissue
Clonal
of new

0 cell line
Somatic
mutation Time

Figure 11.1 Theoretical graph to show the replacement of normal bone marrow cells by a clonal population of

malignant cells arising by successive mitotic divisions from a single cell with an acquired genetic alteration.