Table 1

Summary of mosaicism cases

CaseAgeClinical indicationCFMChromosomal abnormality (CytoRegion)Size (Mb)BdevPredicted mosaicism (%)Karyotype before arrayConfirmationG-band resultFISH result% mosaicism (single cell analysis)*
13 yAutismNoMosaic terminal duplication (2q31.1q37.3)660.04617, 20, 9NoFISH (blood)Normal (blood)nuc ish 2q31.1q37.3 (D2S447)x2 [82] /(D2S447)x3 [18]18% (FISH)
25 yDDNoMosaic interstitial duplication (3p14.3p21.1)2.90.06021, 27, 12NoFISH (blood)Normal (blood)nuc ish 3p14.3-p21.1 (RP11-875H7)x2 [79] /(RP11-875H7)x3 [21]21% (FISH)
36 yDDYesMosaic terminal duplication (5q32-qter)340.07526, 35, 15Yes (N)FISH (blood)Normal (blood and skin)nuc ish 5q35(NSD1)x2 [79]/x3 [19] (blood)20% (FISH)
42 mPre- and postnatal short stature, pulmonary stenosis, dysmorphism, mild DDNoUnknown (chr 9)1400.09733, 48, 19Yes (N)Not confirmedNormal (blood)NP
5FDIUEncephalocoele, neuronal migration disorderNoUnknown (13q12.3-qter)860.04416, 19, 9Yes (N)Not confirmedNormal (amniotic fluid)NP
621 mDD, hypotonia, dysmorphismNoIsodicentric (chr 18)760.0228, 9, 4NoG-band46,XX,idic(18)(q21.1) [7]/46,XX[93] (blood)NP7% (G-band)
74 mHydrops, renal impairment, talipesNoSmall marker chr (18q11.1q11.2)3.40.07426, 35, 15NoFISH/G-band47,XX,+mar(26)/48,XX,+marx2(2)/49,XX,+marx3(1)/46,XX(32) (blood); skin culture normalnuc ish 18cen(D18Z1)x2 [23]/ x3 [27] (blood)
  • 43% (G-band)

  • 54% (FISH)

811 mDD, short statureNoSmall marker chr (19p13.2). Ectopic centromere∼10.09131, 45, 18NoFISHNPish der(19)(p13.32)(RP11-19I2+) (blood)30% (FISH)
917 dHypoplastic aortic arch, microphthalmia, IUGRNoMosaic trisomy (chr 9)1400.08630, 42, 17Yes (N)FISH/G-band2/45 t9 (blood) (post-array review)nuc ish 9cen(CEP9)x2 [77]/ x3 [23] (blood)23% (FISH)
Mosaic UPD (chr 16)890.1853, 113, 36Yes (N)Microsatellite-PCRchr 16 normal (blood)Normal (blood smear)
104 mHemihypertrophyYesMosaic segmental UPD (11p15.1-pter)200.1033, 50, 20Yes (N)Methylation studiesNormal (blood)NP
112 mNeonatal liver impairment, heart murmur, was non-dysmorphic and normal development and growthMosaic segmental UPD (16p11.2-pter)§320.1649, 94, 32NoBy exclusion§Normal (blood)Normal (blood)
124 yMacrocephaly, DD, soft tissue lesion in neck, frontal hair whorlNoMosaic segmental UPD (22q11.21-qter)§320.1033, 50, 20NoBy exclusion§Normal (blood)Normal (blood)
  • Predicted mosaicism levels (%) were calculated from the deviation in BAF for heterozygous genotypes from the ‘typical’ state of 0.5. As there was no deviation in the LogR data to infer the chromosomal abnormality, the predicted level (%) of mosaicism for each case is provided for deletion, duplication and LCSH (bolded values indicate the likely abnormality based on follow-up studies).

  • * The per cent mosaicism as revealed by single cell analysis (ie, FISH or G-band chromosome analysis).

  • 100 cells were analysed for these cases.

  • Molecular analysis of parental samples for cases 8 and 9 showed no evidence of an abnormality involving these chromosomes.

  • § Cases 11 and 12 were consistent with a segmental uniparental disomy based on normal cytogenetics obtained on cultured and uncultured peripheral blood.

  • BAF, B-allele frequency; BMI, body mass index; CFM, clinical features of mosaicism; DD, developmental delay; FDIU, fetal death in utero; FISH, fluorescence in situ hybridisation; IUGR, intrauterine growth retardation; LCSH, long continuous stretches of homozygosity; (N), normal karyotype result; NP, not performed; UPD, uniparental disomy.