Cyclopia

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Obesity, Sleep & Internal medicine
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Cyclopia
Synonyms	Synophthalmia
Pronounce	N/A
Specialty	N/A
Symptoms	Single eye or partially divided eye in a single orbit
Complications	Stillbirth, neonatal death
Onset	Congenital
Duration	Lifelong
Types	N/A
Causes	Genetic disorder, environmental factors
Risks	Trisomy 13, maternal diabetes, alcohol consumption during pregnancy
Diagnosis	Prenatal ultrasound, MRI
Differential diagnosis	Anophthalmia, Microphthalmia
Prevention	Avoidance of known risk factors
Treatment	None
Medication	N/A
Prognosis	Poor
Frequency	1 in 16,000 births
Deaths	N/A

Cyclopia

Cyclopia, named after the mythical one-eyed creature from Greek mythology, the Cyclops, is a rare and complex form of a congenital disorder characterized by the failure of the embryonic prosencephalon to properly divide the orbits of the eye into two cavities.

Embryology and Pathophysiology

During normal embryonic development, the prosencephalon, or forebrain, divides to form two optic vesicles, leading to the development of two separate eyes. In cyclopia, this division process fails to occur, resulting in the formation of a single, central eye.<ref>,

 Association of prenatally diagnosed cyclopia with an increased risk of maternal undiagnosed carcinoma, 
 Prenatal Diagnosis, 
 2017,
 Vol. 37(Issue: 4),
 pp. 323–327,
 DOI: 10.1002/pd.5017,
 PMID: 28109000,</ref>

Clinical Presentation

The clinical presentation of cyclopia is marked by a single eye located where the nose should be and is usually associated with a spectrum of facial and brain anomalies. This includes a missing or a non-functional nose, an abnormally developed brain, and a very small mouth (proboscis). However, the phenotypic severity varies greatly, with the most severe forms incompatible with life.<ref>,

 Cyclopia: Clinical Key Points and Ethical Aspects, 
 American Journal of Medical Genetics Part C: Seminars in Medical Genetics, 
 2019,
 Vol. 181(Issue: 2),
 pp. 280–286,
 DOI: 10.1002/ajmg.c.31697,
 PMID: 30993897,</ref>

Etiology

Cyclopia can be associated with the ingestion of certain substances during pregnancy, such as ethanol and quinacrine, an antimalarial drug. It is also associated with certain genetic conditions, including Patau Syndrome (Trisomy 13) and Holoprosencephaly, the most common structural malformation of the brain that involves incomplete forebrain division.<ref>,

 The molecular genetics of holoprosencephaly, 
 American Journal of Medical Genetics Part C: Seminars in Medical Genetics, 
 2010,
 Vol. 154C(Issue: 1),
 pp. 52–61,
 DOI: 10.1002/ajmg.c.30236,
 PMID: 20104595,</ref>

Diagnosis and Management

The diagnosis of cyclopia is usually made with prenatal ultrasound, followed by MRI or CT for further evaluation. Management is supportive due to the severe associated anomalies and poor prognosis.