Cytogenetics allows detection of genomic anomalies between 10 and 15 Mb (classical cytogenetics) and between 3 and 5 Mb (high-resolution cytogenetics). These pangenomic techniques are associated with more accurate analyses, single probe interstitial FISH and subtelomeric studies. Array-CGH (aCGH) allows high resolution pangenomic analyses. BAC/PAC and oligonucleotides array-CGH have transformed the field of genetics and are useful for constitutional, hematological and solid tumors cytogenetics. Array-based comparative pangenomic hybridization resolutions vary in size (range, several kilobases to 1 Mb). With the more recent improvements, aCGH is becoming the "missing link" between cytogenetics and molecular diagnostics. Despite copy number variations (CNV) and without replacing karyotype, aCGH detects cryptic quantitative anomalies anywhere in the genome and becomes day after day more useful.