In ISCN 2020: An International System for Human Cytogenomic Nomenclature. [Cytogenet Genome Res 2020;160(7–8), DOI: 10.1159/000510090 and 10.1159/isbn.978–3–318–06867–2] by McGowan-Jordan J, Hastings RJ, Moore S (editors), the following corrections to the text should be observed.

In Chapter 8.3 Autosomal Abnormalities, the example “48,XY,+21c,+21” should correctly read “48,XY,+21c,+21[10] An acquired extra chromosome 21 in a patient with Down syndrome.”

The example “46,XY,+21c,-21” should correctly read “46,XY,+21c,-21[10] Acquired loss of one chromosome 21 in a patient with Down syndrome.”

In Chapter 9.2.1 Additional Material of Unknown Origin, the sentence “Additional material of unknown origin replaces the segment 12q13qter” should correctly read “Additional material of unknown origin replaces the segment 12q13->12qter.”

In Chapter 9.2.3 Derivative Chromosomes, the example “53,XX,…,+der(?)t(?;9)(?;q22),+r,+mar,dmin” should correctly read “53,XX,…,+der(?)t(?;9)(?;q22),+r,+mar, >20dmin[20]”.

In Chapter 11.2 Modal Number, the example “81<3n>,XXX,+X,+X,+X,+X,+X,+1,+1,+3,+3,+14,+14,+14,-15,+21” should be written as “81<3n>,XXX,+X,+X,+X,+X,+X,+1,+1,+3,+3,+14,+14,+14,-15,+21[10]”.

In Chapter 13.2.1 Normal Signal Pattern, the example “46,XX.ish 17p11.2(RAI1x2),21q21.3(D21S259/D21S341/D21S342x2)” should correctly read “46,XX.ish 17p11.2(RAI1x2),21q22.13(D21S259/D21S341/D21S342x2)”.

In Chapter 13.2.3 Abnormal Signal Patterns with Multiple Probes, the example “46,X,r(X).ish r(X)(p22.3q21)(KAL+,DXZ1+,XIST+,DXZ4–)” should correctly read “46,X,r(X).ish r(X)(p22.3q21)(KAL1+,DXZ1+,XIST+,DXZ4–)”.

In Chapter 13.2.3 Abnormal Signal Patterns with Multiple Probes, the example “46,XX[20].ish t(12;21)(p13;q22)(ETV6+,RUNX1+;RUNX1+,ETV6+)[5]” should correctly read “46,XX[20].ish t(12;21)(p13;q22)(RUNX1+,ETV6+;RUNX1+,ETV6+)[5]”.

In Chapter 13.2.3 Abnormal Signal Patterns with Multiple Probes, the example “47,XY,+der(4)t(4;11)(p34;q13),t(4;11)[20].ish der(4)(3′KMT2A+),t(4;11)(3′KMT2A+;5′KMT2A+,3′KMT2A–)[5]” should correctly read “47,XY,+der(4)t(4;11)(p34;q23),t(4;11)[20].ish der(4)(3′KMT2A+),t(4;11)(3′KMT2A+;5′KMT2A+,3′KMT2A–)[5]”.

In Chapter 13.2.4 Abnormal Mosaic and Chimeric Signal Patterns with Single or Multiple Probes, the example “ish 21q21.3(D21S259/D21S341/D21S342x3)[20]/21q21.3(D21S259/D21S341/D21S342x2)[30]” should be written as “ish 21q22.13(D21S259/D21S341/D21S342x3)[20]/21q22.13(D21S259/D21S341/D21S342x2)[30]”.

In Chapter 14.2.7 Complex Array Results, the example “arr 17p13.3q11.2(1,207,467_28,236,645)cha[0.5]” should be written as “arr[GRC38] 17p13.3q11.2(1,207,467_28,236,645)cha[0.5]”.

These corrections are displayed in line in ISCN Online. Please visit https://iscn.karger.com/ to access and view the Erratum in context as well as Addenda relating to new developments.