Background: Coffin–Siris syndrome (CSS) is a rare neurodevelopmentaldisorder caused by pathogenic variants in genes of the BAF chromatinremodellingcomplex, most commonly ARID1B. It is characterized bydevelopmental delay, dysmorphic features, seizures, feeding difficulties,and variable fifth-digit anomalies. Marked phenotypic heterogeneity oftenleads to delayed recognition, particularly in resource-limited settings.Methods: We report a case series of four genetically confirmed children with6q25.3–q27 deletions involving ARID1B, evaluated at a tertiary care centre. Clinical,neurological, radiological, audiological, and molecular findings were analyzed.Results: All four children presented in infancy with global developmental delay,recurrent seizures, and significant feeding difficulties requiring nutritionalsupport. Dysmorphic facial features were present in all cases; however, classicalfifth-digit hypoplasia was observed in only one child. Neuroimaging revealedstructural brain abnormalities in all patients, including corpus callosumthinning, cerebellar vermis hypoplasia, hydrocephalus, and periventricularleukomalacia. Electroencephalography showed generalized backgroundslowing in each case. Hearing impairment was identified in three children.Muscle tone varied, with hypotonia in three cases and hypertonia in one,highlighting phenotypic diversity despite a shared molecular basis. Wholeexomesequencing confirmed de novo deletions involving ARID1B in all patients.Conclusion: This case series underscores the broad clinical spectrum ofARID1B-related CSS and demonstrates significant genotype–phenotypevariability even among patients with similar chromosomal deletions. Limbanomalies may be absent, and neurological manifestations predominate.Early genetic evaluation in infants with unexplained developmental delayand dysmorphism facilitates timely diagnosis, multidisciplinary management,and genetic counselling. Increased awareness and integration of moleculartesting are essential to improve recognition of CSS in developing countries.