Shwachman-Diamond syndrome (SDS), an inherited bone marrow failure condition, implies a risk of developing myelodysplastic syndrome/acute myeloid leukaemia. Two clonal chromosome changes are frequent in the bone marrow (BM): an isochromosome of the long arm of chromosome 7, i(7)(q10), and an interstitial deletion of the long arm of chromosome 20, del(20q). We suggested in 2000 a peculiar kind of karyotype instability in SDS, with anomalies of chromosome 7 and 20, including the two most frequent ones. Since 1999, we follow-up a cohort of 97 Italian patients with SDS. Some unexpected odd particularities were found in three cases which further confirm the karyotype instability in BM. Patient UPN 13: patient who developed a clonal del(20q) in 2009. Array-based comparative genomic hybridization (a-CGH) was performed twice, in 2009 and in 2017. The deletion was different in the two analyses: longer in 2009, shorter in 2017. The only explanation is that the two clones with the deletion originated independently, at different times. Patient UPN 24: in 2004, the i(7)(q10) was detected. The a-CGH result obtained in 2006 was as expected, with monosomy of the short arm and trisomy of the long arm. In 2012, a-CGH was repeated and the profile of chromosome 7 was different: the monosomy of the short arm was not homogeneous. Only a structural rearrangement of chromosome 7 short arm additional to the i(7)(q10) may explain this result. Patient UPN 63: patient with the del(20q) found in 2017. In 2018, the a-CGH showed a very small interstitial deletion of the long arm of chromosome 20 (1,729,390 bp): this deletion would not be visible at chromosome analysis. The only explanation is that, at least in 2018, two different clones were present in BM with different del(20q), probably arisen independently from each other.
Novel evidence of karyotype instability in Shwachman Diamond Syndrome
Roberto Valli;Abdul Waheed Khan;Giovanni Porta;Giuseppe Montalbano;Emanuela Maserati;Francesco Pasquali
2019-01-01
Abstract
Shwachman-Diamond syndrome (SDS), an inherited bone marrow failure condition, implies a risk of developing myelodysplastic syndrome/acute myeloid leukaemia. Two clonal chromosome changes are frequent in the bone marrow (BM): an isochromosome of the long arm of chromosome 7, i(7)(q10), and an interstitial deletion of the long arm of chromosome 20, del(20q). We suggested in 2000 a peculiar kind of karyotype instability in SDS, with anomalies of chromosome 7 and 20, including the two most frequent ones. Since 1999, we follow-up a cohort of 97 Italian patients with SDS. Some unexpected odd particularities were found in three cases which further confirm the karyotype instability in BM. Patient UPN 13: patient who developed a clonal del(20q) in 2009. Array-based comparative genomic hybridization (a-CGH) was performed twice, in 2009 and in 2017. The deletion was different in the two analyses: longer in 2009, shorter in 2017. The only explanation is that the two clones with the deletion originated independently, at different times. Patient UPN 24: in 2004, the i(7)(q10) was detected. The a-CGH result obtained in 2006 was as expected, with monosomy of the short arm and trisomy of the long arm. In 2012, a-CGH was repeated and the profile of chromosome 7 was different: the monosomy of the short arm was not homogeneous. Only a structural rearrangement of chromosome 7 short arm additional to the i(7)(q10) may explain this result. Patient UPN 63: patient with the del(20q) found in 2017. In 2018, the a-CGH showed a very small interstitial deletion of the long arm of chromosome 20 (1,729,390 bp): this deletion would not be visible at chromosome analysis. The only explanation is that, at least in 2018, two different clones were present in BM with different del(20q), probably arisen independently from each other.
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