PMC3447255_01
Normal chromosome homologues and relevant rearranged chromosomes in proband and parents; (a) shows the normal and ring chromosomes 21 of the proband; (b) Is a FISH image showing loss of telomeres on the r(21); (c) Shows the Robertsonian translocation chromosome detected in the proband's father.
CRIM.GENETICS2011-158086.001.jpg
PMC3447255_01_CRIM.GENETICS2011-158086.001.jpg
fig1
The initial analysis of 15 cells examined from four independent cultures showed a nonmosaic karyotype of 46,XX,r(21)(p11.2q22.3), Figure 1(a). FISH analysis using a chromosome 21 subtelomere probe on metaphase preparations of both the mother's peripheral blood and amniotic fluid cells from her pregnancy showed loss of the subtelomeric region on the ring chromosome (Figure 1(b)). Interestingly, cytogenetic analysis of the father's blood sample revealed a 45,XY,rob(13;14)(q10;q10) karyotype, with an apparently balanced Robertsonian translocation between chromosomes 13 and 14 (Figure 1(c)).
Location and extent of the loss of genomic DNA on the ring chromosome 21. An ideogram of chromosome 21 and the genes that are located within the deleted region of the ring chromosome 21 are shown. Entries in the DECIPHER database (deletions are shown in red, and duplications are shown in blue), OMIM genes, and RefSeq genes are taken from the UCSC genome browser http://genome.ucsc.edu (Human Mar. 2006 (NCBI36/hg18) assembly). The deletion cases in DECIPHER have proximal breakpoints at positions 40.16 Mb (case 253457), 43.99 Mb (case 253454), and 45.35 Mb (case 2126), and that reported by Bertini et al. (not shown above) starts at 43.50 Mb; all four deletions end at 46.89 Mb. The COL6A1, COL6A2, and PCNT genes are shown in red boxes. The horizontal red line with arrow heads denotes the extent of the chromosome 21 loss detected in the case reported here.
CRIM.GENETICS2011-158086.002.jpg
PMC3447255_01_CRIM.GENETICS2011-158086.002.jpg
fig2
Monosomy was detected for a 1138 kb region with the chromosome 21 coordinates 45795806 bp-46933606 bp (Human Mar. 2006 (hg18) assembly, Figure 2). 
PMC3447255_02