Fig. 2

Genetic characterization of UPD(20)mat. (a) Family pedigree: filled symbol indicates the homozygous-affected proband and symbol with dot denotes carrier mother. Parents-to-proband segregation of alleles at 6 microsatellites spanning chromosome 20 is shown. Short tandem repeat (STR) markers mapping within the disomic region are highlighted in bold. Chromatograms of parents and proband targeted on the variant genomic position. (b) SNP-array profile of patient chromosome 20. Top plot shows B allele frequency revealing an 13.6 Mb isodisomic region (20q13.13-qter) including SALL4, CYP24A1, MC3R, AURKA, PCK1, VAPB, STX16, GNAS, TUBB1, EDN3, OSBPL2, GATA5, COL9A3, SCLC7A9, RTEL1, CHRNA4, KCNQ2, EEF1A2, PRPF6, NDAJC5 and SOX18, imprinted loci; bottom plot shows Log R ratio, which reveals a proper biallelic contribution. (c) Estimated mechanism of UPD(20)mat event from gametogenesis to embryo. 1: As a first step, crossing-over during maternal gametogenesis, followed by non-disjunction during Meiosis I; 2: trisomic cell at first zygote stage; 3.trisomic rescue at early zygote stage