Page 493 - Clinical Hematology_ Theory _ Procedures ( PDFDrive )

CHAPTER 24 ■ Myelodysplastic Syndromes and Myelodysplastic/Myeloproliferative Neoplasms 477

Chromosomal Abnormalities

TABLE 24.2 WHO Subtypes
Cytogenetic i erences exist between pri ry ( e novo) n

secon ry MDSs n y be observe on initi l bone r-
2008 Revision 2016 Revision
row observ tion or uring evolution o the ise se. Clon l

Refractory cytopenia with a MDS with single lineage cytogenetic bnor lities re observe in bout 50% o MDS

unilineage dysplasia (RCUD) dysplasia (MDS-SLD) c ses. So e chro oso l lter tions see to be consistently
involve in the p thogenetic ech nis s o secon ry leu-

ke i n MDS.
Clon l chro oso l no lies y be observe uring

initi l bone rrow n lysis or seen s the result o k ryotypic

Refractory anemia with ring MDS with ring sideroblasts evolution uring ise se progression. T ese bnor lities y

sideroblasts (RARS) (MDS-RS) be onoso ic or triso ic in n ture n y involve p rti l
or tot l chro oso l lter tions. Most chro oso es ispl y
Two subtypes: SLD, MLD
recurrent loss o chro oso l teri l r ther th n the tr ns-
Refractory cytopenia MDS with multilineage loc tions or inversions co only oun in AML. In ny

with multilineage dys- dysplasia (MDS-MLD) inst nces, the cytogenetic bnor lities beco e co plex n

plasia (RCMD) (with ring involve ore th n one chro oso e. Co plex k ryotypes (≥3

sideroblasts) bnor lities) typic lly inclu e chro oso es 5 n 7.

Refractory anemia with MDS with excess blasts T e ost requent cytogenetic lter tions re in the

excess blasts (RAEB) (MEB) rker chro oso es: 5 ( onoso y or 5q-), 7 ( onoso y,

p rti l loss o the long r , 7q-, re rr nge ent), n 8 (tri-
so y or re rr nge ent). Other i plic te chro oso es re

1, 3 ( onoso y), 4 ( onoso y), 9, 12, 17, 20 (20q-), n 21
MDS with isolated del (5q) MDS with isolated del (5q) s well s the Y chro oso e (loss).

MDS, unclassi ed (MDS-U) MDS-U T e ost requent bnor lities in chil ren re triso y

Refractory cytopenia of Refractory cytopenia of 8, onoso y 7, n eletions involving the long r s o

childhood (RCC) provisional childhood (RCC) provisional chro oso es 20 n X. In chil ren with MDS, n bnor-
lity like onoso y 7 is typic l n prob bly in ic tes n

un vor ble prognosis.
lkyl ting gents in uce DNA cross-link ges, which bec use

o unequ l cross-over y pl ce DNA in juxt position to Consequences

cert in oncogenes. T e oncogenes y then beco e cti- Chro oso l lter tions, ostly o the elete type, re

v te n le to the evelop ent o lign nt clone o ssu e to pl y specif c role in the genesis o MDS. T ese

bone rrow cells, which evelops into MDS.
bnor lities re perh ps re ections o n lter tion o

■ Other actors. Abuse o prescription or over-the-counter oncogene unction n lter tions o pro uction o growth

rugs y lso be c us tive o MDS. Although no f r ctors n their receptors th t y le to proli er tion o

rel tionship h s been est blishe to te, rugs such s the bnor l clone. So e theories suggest th t bnor li-

n lgesics, tr nquilizers, n nonsteroi l nti-in - ties in the pro uction o growth ctors or receptors rel te to

tory rugs y eventu lly be linke to the p thogenesis o the evelop ent o MDS.

MDS (si erobl stic ne i ). In pri ry MDS, bnor l growth o the gr nulocyte-
croph ge precursor, colony- or ing unit–gr nulocyte-

NOTE: This is a good time to review the de nitions of Key croph ge (CFU-GM), occurs in pproxi tely 79% o

Terms in the Glossary and ash cards on . It is also p tients, n clon l chro oso e bnor lities occur in n

a good time to complete Review Questions related to the ver ge o 34% o p tients.

previous content.
Relationship of Cytogenetics to Prognosis

Epidemiology Surviv l o p tients with MDS is better or those with nor l
chro oso l p tterns. Both single-chro oso e no lies

MDS is r re in chil hoo . T e ult or usu lly occurs in n ultiple cytogenetic ch nges re signif c nt. Sequenti l

persons ol er th n 50 ye rs o ge ( ost p tients re 60 to 75 cytogenetic stu ies e onstr te th t ost p tients whose

ye rs ol ). MDS is ore co on in les. con itions tr ns or to cute leuke i exhibit k ryotypic

T e inci ence o MDS is still unknown but is prob bly evolution. T e existence o onoso y 5 or onoso y 7 c n

si il r to th t o cute leuke i . T ere re esti te to be be use ul in i enti ying p tients in who cute leuke i will

t le st 1,500 to 2,000 c ses nnu lly in the Unite St tes. prob bly evelop.

Te prev lence o MDS, however, y be s high s 1:500 in Te occurrence o triso y 11 in MDS n in AML sug-

in ivi u ls ol er th n 55 ye rs o ge. gests th t this bnor lity c n be specif c lly ssoci te with