Tietz syndrome and Waardenburg syndrome type 2A are allelic conditions caused by 
MITF mutations. Tietz syndrome is inherited in an autosomal dominant pattern and 
is characterized by congenital deafness and generalized skin, hair, and eye 
hypopigmentation, while Waardenburg syndrome type 2A typically includes variable 
degrees of sensorineural hearing loss and patches of de-pigmented skin, hair, 
and irides. In this paper, we report two unrelated families with MITF mutations. 
The first family showed an autosomal dominant pattern and variable expressivity. 
The second patient was isolated. MITF gene analysis in the first family 
demonstrated a c.648A>C heterozygous mutation in exon 8 c.648A>C; p. (R216S), 
while in the isolated patient, an apparently de novo heterozygous 
c.1183_1184insG truncating mutation was demonstrated in exon 10. All patients 
except one had bilateral reduced ocular anteroposterior axial length and a high 
hyperopic refractive error corresponding to posterior microphthalmos, features 
that have not been described as part of the disease. Our results suggest that 
posterior microphthalmos might be part of the clinical characteristics of 
Tietz/Waardenburg syndrome type 2A and expand both the clinical and molecular 
spectrum of the disease. © 2016 Wiley Periodicals, Inc.