title: Peters Anomaly in Twins: A Case Report of a Rare Incident with Novel Comorbidities.
abstract: BACKGROUND
  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.
  
  
  METHODS
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: King Abdullah International Medical Research Center, Department of Ophthalmology, King Abdulaziz Medical City, Ministry of National Guard Health Affairs (MNG-HA), Jeddah, Saudi Arabia.
authors.forename: Hashem S
authors.initials: HS
authors.lastname: Almarzouki
authors.affiliation: King Abdullah International Medical Research Center, Department of Ophthalmology, King Abdulaziz University Hospital, Jeddah, Saudi Arabia.
authors.forename: Alaa A
authors.initials: AA
authors.lastname: Tayyib
authors.affiliation: King Abdullah International Medical Research Center, College of Medicine, King Saud bin Abdulaziz University for Health Sciences, Ministry of National Guard Health Affairs (MNG-HA), Jeddah, Saudi Arabia.
authors.forename: Hassan A
authors.initials: HA
authors.lastname: Khayat
authors.affiliation: King Abdullah International Medical Research Center, College of Medicine, King Saud bin Abdulaziz University for Health Sciences, Ministry of National Guard Health Affairs (MNG-HA), Jeddah, Saudi Arabia.
authors.forename: Raed E
authors.initials: RE
authors.lastname: Alsulami
authors.affiliation: King Abdullah International Medical Research Center, College of Medicine, King Saud bin Abdulaziz University for Health Sciences, Ministry of National Guard Health Affairs (MNG-HA), Jeddah, Saudi Arabia.
authors.forename: Saeed M
authors.initials: SM
authors.lastname: Alzahrani
authors.affiliation: King Abdullah International Medical Research Center, College of Medicine, King Saud bin Abdulaziz University for Health Sciences, Ministry of National Guard Health Affairs (MNG-HA), Jeddah, Saudi Arabia.
authors.forename: Abdulaziz S
authors.initials: AS
authors.lastname: Alkahtani
authors.affiliation: King Abdullah International Medical Research Center, College of Medicine, Umm Al-Qura University, Mecca, Saudi Arabia.
authors.forename: Loai S
authors.initials: LS
authors.lastname: Alghifees
keywords: Comorbidities; Genetic basis; Monozygotic twins; Ocular abnormalities; Peters anomaly; Systemic malformation