Expected disease frequency?

A disorder called complete achromatopsia ociated with skeletal anomalies is a newly discovered autosomal recessive syndrome (Garcia-Ortiz< et al. Genet Couns. 2004;15(4):455-61) Achromatopsia or rod monochromatism is the complete absence of color discrimination, with an estimated allele frequency of 1 in 100,000. Given that frequency, what is the expected disease frequency in the population?