We thank Parsa et al for their valuable contribution concerning the
appropriate nomenclature for ocular findings and PAX2 mutation.
The word "coloboma" is derived from the Greek, meaning curtailed or mutilated.
In ophthalmology, a coloboma is any "notch, gap, hole, or fissure in any ocular
structures, whether congenital or acquired."1 Primary
isolated optic nerve coloboma is considered part of a spectrum of phenotypic
expressions of colobomatous malformations, ranging from iris coloboma to orbital
cyst. Intermediate in this range is coloboma of the choroid and retina, which
may be limited to the quadrant inferonasal to the optic disc or may encompass
the optic disc with or without sparing the macula. Coloboma of the optic disc
may occur, then, with chorioretinal coloboma or as the only fundus lesion
and may result from failure of closure of the most proximal portion of the
optic stalk. The disc is enlarged, often vertically oval and always excavated,
and the coloboma may involve the entire disc or just the inferior portion.
Patients with renal-coloboma syndrome and a PAX2 mutation have
ocular abnormalities representing part of the spectrum of colobomatous abnormalities,
including optic nerve colobomas, chorioretinal colobomas, and/or orbital cysts,
but they do not have iris colobomas2 (Table 1). The patients in our report had
a PAX2 mutation with a wide spectrum of phenotypic expression
of optic nerve abnormalities, ranging from an optic pit to a large coloboma.3
Gus PI, Giugliani R, de Souza CFM, Eccles M, Porteous S. Papillorenal Syndrome in a Brazilian Family. Arch Ophthalmol. 2002;120(12):1772-1773. doi: