Peters Anomaly in Twins: A Case Report of a Rare Incident with Novel Comorbidities

Abstract

Introduction: Peters anomaly is a rare developmental malformation involving the anterior segment of the eye, which culminates in amblyopia or congenital blindness. Multiple ocular and/or systemic malformations have been observed with this anomaly, and novel comorbidities continue to be reported.

Case presentation: The probands were monozygotic twin boys (twin I and twin II) born to consanguineous parents at 36 weeks of gestation. Coarse facial features and deep-seated eyes were noted at birth. At 6 months, ophthalmic examination revealed that both twins were unable to blink in response to light, or to fixate and follow a moving object. Both twins had prominent horizontal nystagmus. Slit-lamp examination demonstrated varying degrees of central leukoma (corneal opacity) associated with iridocorneal adhesion, which is characteristic of type I Peters anomaly. No cataractous changes were observed. Normal intraocular pressure and disorganized retina were observed. Pupillary abnormalities included bilaterally underdeveloped pupils and bilateral absence of pupils was noted. Ocular MRI showed bilateral microphthalmia and optic nerve hypoplasia, with a small optic chiasm in both twins. At this age, the diagnosis of Peters anomaly was made. At 16 months of age, both twins developed deep venous thrombosis and purpuric skin lesions. Investigations revealed a hereditary thrombophilia secondary to a homozygous mutation causing protein C deficiency, which is a rare thrombotic condition. Ocular ultrasonography revealed bilateral vitreous hemorrhaging linked to altered coagulation. One twin developed bilateral inguinal hernia and cryptorchidism.

Conclusion: The novel concordance of Peters anomaly in these monozygotic twins sharing a mutation in PROC gene provides further evidence that this anomaly has a genetic basis. Hypoplasia of the optic nerves and optic chiasm, along with severe protein C deficiency and bilateral absence of the pupils, are associated comorbidities that have not previously been reported with this anomaly.

Keywords: Comorbidities; Genetic basis; Monozygotic twins; Ocular abnormalities; Peters anomaly; Systemic malformation.

Fig. 1

Photograph of the gross anatomy of the left eye of twin I, showing central corneal opacity.

Fig. 2

Photograph of the gross anatomy of the right eye of twin II, showing prominent central corneal opacity.

Fig. 3

T2-weighted MRI brain scan of twin II, showing bilateral microphthalmia with abnormal dysmorphic changes in the anterior chamber. Bilateral hypoplastic changes of the optic nerve were noted (arrowheads), along with a small optic chiasm. Similar abnormalities were observed in twin I.