Karyotype of patients showing in (A), FISH with whole chromosome paint 1 exclude the posibility of the missing material elsewhere in the genome (B) and subtelomeric FISH presenting in (C). Multicolor chromosome banding for Patient 1 clearly shows an extremely altered pattern on the derivative chromosome 1 (D). Using additional microdissection derived probes (MD45: stains 1pter-1p36.2, 1p35-1p33 and 1p22, MD50: stains 1q42-qter) in combination with a subtelomeric probe for chromosome 1qter (ST1q) or a partial chromosome paint for the long arm of chromosome 1 (pcp 1q) are shown in figure parts E and F, respectively (E-F). To control the results of array-CGH BAC RP11-960C20 in 1p34.2 was applied and confirmed deletion of the corresponding region on the derivatve chromosome 1. Thus, the derivative chromosome 1 could be described as der(1)(pter->p34.2::q43~44->p34.2:) (G).