Tuberous sclerosis complex (TSC) is a neurocutaneous disorder that results from mutations within either theTSC1gene or theTSC2gene. Diagnosis is based on well-established clinical criteria or genetic criteria. We describe an 18-month-old boy who presented with seizures and a single hypopigmented macule. He did not meet consensus criteria for the clinical diagnosis of TSC. Exome sequencing revealed a heterozygousTSC2mutation (c.5138G>A (p.Arg1713His)) in the patient. This heterozygous alteration was detected in his mother as well as several other maternal family members. The mother and other family members with the mutation were asymptomatic except for the presence of hypopigmented macules. The phenotypic characteristics of the individuals in this family were not suggestive of aTSC2mutation as none satisfied the clinical criteria for even a diagnosis of possible TSC. This case provides evidence for a uniqueTSC2mutation that resulted in an atypical clinical presentation and indicates potential shortcomings of the current diagnostic criteria for TSC. These findings may have implications for genetic counseling and screening.