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Neurological disorders may have a varied genetic etiology.  In the last couple of years due to easy availability of NGS based testing and relatively reduced costs, there has been an inclination towards considering these tests as first line investigations in majority cases with a neurological involvement. These tests may sometimes be considered despite phenotypic clues of an underlying cytogenetic cause. It must however be emphasized that neurological disorders may occasionally occur due to a chromosomal aberration or a microdeletion which may be missed on the current NGS based strategies. Common chromosomal disorders like Down syndrome, Prader Willi/ Angelman syndromes are known to cause epilepsy, developmental delay etc. But here we present some rare cases with gross chromosomal aberrations such as- deletion 1p36, deletion 4pter, deletion 13qter (mosaic), ring chromosome 9, ring chromosome 20, ring chromosome 21, certain imbalanced translocations etc. leading to the above neurological sequelae. Similarly neurological phenotypes of rare microdeletion syndromes pertaining to certain chromosomal regions such as- 2q37, 4p16, 6q21, 8q23, 11q24, 22q13 and some novel hitherto undescribed syndromes will also be presented. Hence our case series highlight the need be prudent and look at the physical phenotype, constellation of symptoms, and pedigree before planning a genetic test. Here we intend to highlight the importance and the role of chromosomal and microarray testing in the evaluation of cases with developmental delay and epilepsy.

Microarray, epilepsy, developmental delay, new phenotypes