Correlation between chromosome deletion and phenotypes in two cases of ring chromosome 6 syndrome / 中华围产医学杂志

ABSTRACT

Objective To understand the correlation between chromosome deletion and the phenotypes in cases of ring chromosome 6 syndrome.Methods Two cases of ring chromosome 6 syndrome persented to the Peking University First Hospital in 2013 were studied.Case 1 was a fetus diagnosed as having ring chromosome 6 with karyotype 46,XY,r (6) [14]/46,XY,r (6; 6) [1]/45,XY,-6[15] from a pregnant woman who received prenatal examination because of high risk found in serum screening for Down's syndrome at 21 +1 weeks of gestation.Case 2 was an eight-month-old female infant with growth retardation and congenital facial anomaly,whose karyotype was 46,XX,r (6) /47,XX,r (6) × 2/46,XX,r (6; 6) /45,XX,-6.Multiplex ligation-dependent probe amplification and array-based comparative genomic hybridization were used to detect the location of chromosome telomeric loss and its size,and the correlation between chromosome deletion and the phenotypes was analyzed by reviewing related literatures.Results Case 1 was confirmed to have short-arm terminal deletions on 6p25.3-25.2 (2.42 Mb) which mainly included DUSP22,IRF4,EXOC2,FOXC1,FOXF2 and FOXQ genes,and long-arm terminal deletions on 6q26-27 (7.84 Mb) mainly included PARK2,PACRG,LOC28596 and RPS6KA2 genes.Case 2 had short-arm terminal deletions on 6p25.3-25.1 (5.44 Mb) which included DUSP22,IRF4,EXOC2,FOXC1,FOXF2,FOXQ and SERPINB6 genes,and long-arm terminal deletions on 6q27 (0.16 Mb) which included PSMB1,TBP and PDCD2 genes.Except for the growth retardation,the common feature of ring syndrome,in both cases,cerebellum hypoplasia was observed in case 1,and microcephaly and esotropia were observed in case 2.Conclusions The difference of phenotypes in patients with a ring chromosome 6 is closely associated with the location and size of the deletion in chromosome 6.