Iridogoniodysgenesis
Overview
Iridogoniodysgenesis is a rare, autosomal dominant disorder that affects the anterior segment of the eye, characterized by malformations of the iris stroma and trabecular meshwork. This often leads to iris hypoplasia (a lack of development), and a significant portion of affected individuals develop juvenile glaucoma, which is often resistant to medication and can cause vision loss. The condition is caused by abnormal development of neural crest cells, which are crucial for forming the eye's anterior segment structures.
Symptoms
Ocular symptoms
Iris hypoplasia: The iris is underdeveloped and may appear smooth with a loss of normal crypts and folds.
Unusual eye color: Due to the hypoplastic iris, a dark gray or chocolate-brown color can be present because the inner pigmented layer is more visible.
Glaucoma: Increased intraocular pressure can lead to juvenile glaucoma, often diagnosed in childhood or adolescence.
Vision loss: Glaucoma can cause vision loss or blindness if left untreated.
Pupillary abnormalities: Mild pupillary deformities can be present.
Systemic symptoms
Dental anomalies: Missing teeth (anodontia) or abnormally small teeth (microdontia).
Maxillary hypoplasia: Underdevelopment of the upper jaw.
Hernias: Inguinal or periumbilical hernias.
Hypospadias: A condition in males where the opening of the urethra is on the underside of the penis.
Cerebellar vermis hypoplasia: In some cases, there may be underdevelopment of the cerebellum.
Causes
Iridogoniodysgenesis is caused by an abnormal migration or development of neural crest cells, leading to malformations in the anterior segment of the eye. It is primarily caused by mutations in two genes: the PITX2 gene (chromosome 4q25), which causes the syndrome with systemic features, and the FOXC1 gene (chromosome 6p25), which typically causes the anomaly without systemic features.
Genetic mutations: Iridogoniodysgenesis is an autosomal dominant disorder, meaning a person only needs one copy of the mutated gene from one parent to develop the condition.
PITX2 gene: Mutations in this gene are linked to iridogoniodysgenesis syndrome, which can include extraocular abnormalities like maxillary hypoplasia, dental problems, and hernias, as well as ocular changes.
FOXC1 gene: Mutations in this gene typically lead to iridogoniodysgenesis anomaly, which primarily involves eye malformations and is less likely to have systemic features.
Cellular defect: The underlying cause is a defect in the development of neural crest cells, which are responsible for forming many structures in the anterior segment of the eye. This results in abnormal differentiation of the iris stroma and trabecular meshwork, leading to a variety of ocular issues.
Diagnosis
Ocular findings
Iris hypoplasia: The iris stroma is underdeveloped, causing the pigmented epithelium to show through, giving it a dark chocolate-brown or slate-gray color.
Goniodysgenesis: Malformation of the iridocorneal angle, with potential mesodermal remnants, iridotrabecular adhesions, and abnormal angle vasculature.
Increased intraocular pressure: Elevated IOP leading to a high risk of developing juvenile glaucoma.
Glaucoma: May be detectable at birth, but can also be diagnosed later in life.
Pupillary abnormalities: Mild deformities may be present, but the pupil is often normal in morphology and location.
Systemic findings
Maxillary hypoplasia
Microdontia (small teeth) or anodontia (missing teeth)
Redundant periumbilical skin
Inguinal hernia
Hypospadias in males
Treatment
Medical management: Medications can be used to lower intraocular pressure, particularly in the early stages after diagnosis.
Surgical intervention: When medical treatments are not enough, surgery is often necessary to manage glaucoma.
Trabeculectomy: A surgical procedure to create a new drainage channel for the eye's fluid.
Aqueous shunt procedure: A device is implanted to help drain fluid and lower pressure.
Diode laser cycloablation: A laser is used to reduce fluid production in the eye.
Surgical repair of iridodialysis: If symptomatic, surgery may be needed to repair tears in the iris.
Continuous monitoring and follow-up: Due to the high risk of glaucoma and vision loss, frequent and close monitoring is essential. Treatment may involve a combination of different surgical procedures over time.
Type of Doctor Department : An ophthalmologist
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