Propionic acidemia is a metabolic disorder (OMIM 606054) caused by deficiency of the propionyl-coenzyme A (CoA) carboxylase, which subsequently results in accumulation of propionic acid. Patients may initially present with poor feeding, vomiting, loss of appetite, hypotonia, and lethargy. Later, most children will show different degrees of motor, social and language delay even more serious medical problems, including heart abnormalities, seizures, coma, and possibly death. Two siblings affected with propionic acidemia were screened for putative mutations in PCCA and PCCB genes coding alpha and beta subunits of propionyl-coenzyme A (CoA) carboxylase, respectively. Both patients had a mild-severe form of propionic acidemia. The investigations using PCR, long-PCR, array comparative genomic hybridization (aCGH), and sequencing techniques showed a approximately 73kb deletion extending from intron 16 to intron 19 and an 18bp insertion at the distal end of the deletion in PCCA gene. The deletion so far is the largest gross change reported in the literature for the PCCA gene.