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Although most recognized for its correlation with the onset of glaucoma, the malformation is not limited to the eye, as Axenfeld syndrome when associated with the PITX2 genetic mutation usually presents congenital malformations of the face, teeth, and skeletal system.
The most characteristic feature affecting the eye is a distinct corneal posterior arcuate ring, known as an "embryotoxon". The iris is commonly adherent to the Schwalbe's line (posterior surface of the cornea).
Diagnosis
One of the three known genetic mutations which cause Rieger Syndrome can be identified through genetic samples analysis. About 40% of Axenfeld-Rieger sufferers have displayed mutations in genes PITX2, FOXC1, and PAX6. The difference between Type 1, 2, and 3 Axenfeld Syndrome is the genetic cause, all three types display the same symptoms and abnormalities.
The OMIM classification is as follows:
Detection of any of these mutations can give patients a clear diagnosis and prenatal procedures such as preimplantation genetic diagnosis, Chorionic villus sampling and Amniocentesis can be offered to patients and prospective parents.
Since Duane-radial ray syndrome is a genetic disorder, a genetic test would be performed. One test that can be used is the SALL4 sequence analysis that is used to detect if SALL4 is present. If there is no pathogenic variant observed, a deletion/duplication analysis can be ordered following the SALL4 sequence analysis. As an alternative, another genetic test called a multi-gene panel can be ordered to detect SALL4 and any other genes of interest. The methods used for this panel vary depending on the laboratory.
Evaluations by certain specialists should be performed following the initial diagnosis of Duane-radial ray syndrome. These evaluations will be used to determine the extent of the disease as well as the needs of the individual.
- Eyes - Complete eye exam by an ophthalmologist especially focusing on the extraocular movements of the eye and the structural eye defects
- Heart - evaluation by a cardiologist along with an echocardiogram and ECG
- Kidneys - Laboratory tests to check kidney function and a renal ultrasound
- Hearing
- Endocrine - evaluation for growth hormone deficit if growth retardation present
- Blood - CBC to check for thrombocytopenia and leukocytosis
- Clinical genetics consultation
It is named after the German ophthalmologist Theodor Axenfeld who studied anterior segment disorders, especially those such as Rieger Syndrome and the Axenfeld Anomaly.
Axenfeld-Rieger syndrome is characterized by abnormalities of the eyes, teeth, and facial structure. Rieger Syndrome, by medical definition, is determined by the presence of malformed teeth, underdeveloped anterior segment of the eyes, and cardiac problems associated with the Axenfeld anomaly. The term "Rieger syndrome" is sometimes used to indicate an association with glaucoma. Glaucoma occurs in up to 50% of patients with Rieger Syndrome. Glaucoma develops during adolescence or late-childhood, but often occurs in infancy. In addition, a prominent Schwalbe's line, an opaque ring around the cornea known as posterior embryotoxon, may arise with hypoplasia of the iris. Below average height and stature, stunted development of the mid-facial features and mental deficiencies may also be observed in patients.
The diagnosis is based on the combination of unusual facial features and the dysplastic or absent femurs.
Diagnosis may be made antenatally.
The condition is often diagnosed through an MRI or ultrasound. Consulting a specialist (in this case a gynecologist) is recommended.
There is no known specific treatment for this condition. Management is supportive.
Persistent tunica vasculosa lentis is a congenital ocular anomaly. It is a form of persistent hyperplastic primary vitreous (PHPV).
It is a developmental disorder of the vitreous. It is usually unilateral and first noticed in the neonatal period. It may be associated with micropthalmos, cataracts, and increased intraocular pressure. Elongated ciliary processes are visible through the dilated pupil. A USG B-scan confirms diagnosis in the presence of a cataract.
Causes a ‘white reflex’ in the affected eye (leukocoria), prompting further investigation.
Persistent hyperplastic primary vitreous (PHPV), also known as Persistent Fetal Vasculature (PFV), is a rare congenital developmental anomaly of the eye that results
following failure of the embryological, primary vitreous and hyaloid vasculature to regress. It can be present in three forms: purely anterior (persistent tunica vasculosa lentis and persistent posterior fetal fibrovascular sheath of the lens), purely posterior (falciform retinal septum and ablatio falcicormis congenita) and a combination of both. Most examples of PHPV are unilateral and non-hereditary. When bilateral, PHPV may follow an autosomal recessive or autosomal dominant inheritance pattern.
The first noticeable signs of the syndrome usually do not appear until after the first twelve months of the child’s life. The child usually has severe balance issues as he or she learns to sit or walk, often leaning or tilting the head toward the good eye to correct the brain’s skewed perception of the world. Often the child will fall in the same direction while walking or run into objects that are placed on his or her blind side. Additionally, family members may notice a white reflex in the pupil of an affected child instead of the normal red reflex when taking photographs. The presence of this phenomenon is dependent on the degree of the coloboma, with larger colobomas more likely to manifest this particular phenomenon.
This anomaly must be confirmed through pupillary dilation and examination of the optic disc, as the symptoms alone do not constitute a diagnosis.
People with optic nerve colobomas live relatively normal lives. Although non-prescription glasses should be worn for eye protection, this syndrome does not usually prevent the individual from living a normal life, driving cars, playing sports, reading, etc. Certain activities, however, may be more difficult for patients with optic nerve colobomas due to a compromised view of the world. Like most other eye conditions, a diagnosis of optic nerve coloboma precludes a person from certain occupations.
Microspherophakia is a rare congenital autosomal recessive condition where the lens of the eye is smaller than normal and spherically shaped. This condition may be associated with a number of disorders including Peter's anomaly, Marfan syndrome, and Weill–Marchesani syndrome. The spherical shape is caused by an underdeveloped zonule of Zinn, which doesn't exert enough force on the lens to make it form the usual oval shape. It is a result of a homozygous mutation to the LTBP2 gene.
Fleischer's syndrome is an extremely rare congenital anomaly characterized by displacement of the nipples, occasional polymastia, and hypoplasia of both kidneys.
Anterior segment mesenchymal dysgenesis is a failure of the normal development of the tissues of the anterior segment of the eye. It leads to anomalies in the structure of the mature anterior segment, associated with an increased risk of glaucoma and corneal opacity.
Peters' (frequently misspelled Peter's) anomaly is a specific type of mesenchymal anterior segment dysgenesis, in which there is central corneal leukoma, adhesions of the iris and cornea, and abnormalities of the posterior corneal stroma, Descemet's membrane, corneal endothelium, lens, and anterior chamber.
Although rare, this condition is often treatable with surgery. In most cases, the blind hemivagina is opened, and the fluid drained.
Wildervanck syndrome or cervico-oculo-acoustic syndrome comprises a triad of:
- Duane syndrome
- Klippel-Feil anomaly (fused cervical vertebrae)
- congenital hearing loss
Shprintzen–Goldberg syndrome is a multiple anomaly syndrome that has craniosynostosis, multiple abdominal hernias, cognitive impairment, and other skeletal malformations as key features. Several reports have linked the syndrome to a mutation in the "FBN1" gene, but these cases do not resemble those initially described in the medical literature in 1982 by Shprintzen and Goldberg, and Greally et al. in 1998 failed to find a causal link to FBN1. At this time, the cause of Shprintzen–Goldberg syndrome remains uncertain. The syndrome is rare with fewer than 50 cases described in the medical literature to date.
The morning glory disc anomaly (MGDA) is a congenital deformity resulting from failure of the optic nerve to completely form in utero. The term was coined in 1970 by Kindler, noting a resemblance of the malformed optic nerve to the morning glory flower. The condition is usually unilateral.
On fundoscopic examination, there are three principal findings comprising the anomaly:
1. an enlarged, funnel-shaped excavation in optic disc
2. an annulus or ring of pigmentary changes surrounding the optic disc excavation
3. a central glial tuft overlying the optic disc
There is no consensus on what degree of angulation justifies a diagnosis, an incline between 15° and 30° is typical. A similar-sounding term, camptodactyly, is a fixed flexion deformity of a digit.
Coloboma of optic nerve, is a rare defect of the optic nerve that causes moderate to severe visual field defects.
Coloboma of the optic nerve is a congenital anomaly of the optic disc in which there is a defect of the inferior aspect of the optic nerve. The issue stems from incomplete closure of the embryonic fissure while in utero. A varying amount of glial tissue typically fills the defect, manifests as a white mass.
Asymmetric crying facies (ACF), also called Cayler cardiofacial syndrome, partial unilateral facial paresis and hypoplasia of depressor angula oris muscle, is a minor congenital anomaly caused by agenesis or hypoplasia of the depressor anguli oris muscle, one of the muscles that control the movements of the lower lip. This unilateral facial weakness is first noticed when the infant cries or smiles, affecting only one corner of the mouth and occurs on the left side in nearly 80% of cases. It is associated with other birth defects in more than 50% of cases.
When the hypoplasia of the depressor anguli oris muscle is associated with congenital cardiac defects, the term 'Cayler cardiofacial syndrome' is used.
Cayler syndrome is part of 22q11.2 deletion syndrome.
It was characterized by Cayler in 1969.
Several gene mutations have been identified underlying these anomalies with the majority of ASD genes encoding transcriptional regulators. In this review, the role of the ASD genes, PITX2 and FOXC1, is considered in relation to the embryology of the anterior segment, the biochemical function of these proteins, and their role in development and disease aetiology. The emerging view is that these genes act in concert to specify a population of mesenchymal progenitor cells, mainly of neural crest origin, as they migrate anteriorly around the embryonic optic cup. These same genes then regulate mesenchymal cell differentiation to give rise to distinct anterior segment tissues. Development appears critically sensitive to gene dosage, and variation in the normal level of transcription factor activity causes a range of anterior segment anomalies. Interplay between PITX2 and FOXC1 in the development of different anterior segment tissues may partly explain the phenotypic variability and the genetic heterogeneity characteristic of ASD. In the most recent research, the PAX6 gene has been implicated in Peters' Anomaly
Peters plus syndrome (Krause–van Schooneveld–Kivlin syndrome) is a hereditary syndrome that mainly affects the eyes, growth and development of the individual. It is also known as Krause–Kivlin syndrome.
Features of this syndrome include Peters anomaly, leukoma (corneal opacity), central defect of Descemet's membrane, and shallow anterior chamber with synechiae between the iris and cornea. It is associated with short limb dwarfism and delayed mental development.
Krause–van Schooneveld–Kivlin syndrome is listed as a "rare disease" by the Office of Rare Diseases (ORD) of the National Institutes of Health (NIH), which means that the syndrome, or a subtype, affects fewer than 200,000 people in the United States.
It is associated with the enzyme "B3GALTL".
It was characterized in 1984 by van Schooneveld.
Anomalies resembling Pelger–Huët anomaly that are acquired rather than congenital have been described as pseudo Pelger–Huët anomaly. These can develop in the course of acute myelogenous leukemia or chronic myelogenous leukemia and in myelodysplastic syndrome. It has also been described in Filovirus disease.
In patients with these conditions, the pseudo–Pelger–Huët cells tend to appear late in the disease and often appear after considerable chemotherapy has been administered. The morphologic changes have also been described in myxedema associated with panhypopituitarism, vitamin B12 and folate deficiency, multiple myeloma, enteroviral infections, malaria, muscular dystrophy, leukemoid reaction secondary to metastases to the bone marrow, and drug sensitivity, sulfa and valproate toxicities are examples. In some of these conditions, especially the drug-induced cases, identifying the change as Pelger–Huët anomaly is important because it obviates the need for further unnecessary testing for cancer.
Peripheral blood smear shows a predominance of neutrophils with bilobed nuclei which are composed of two nuclear masses connected with a thin filament of chromatin. It resembles the pince-nez glasses, so it is often referred to as pince-nez appearance. Usually the congenital form is not associated with thrombocytopenia and leukopenia, so if these features are present more detailed search for myelodysplasia is warranted, as pseudo-Pelger–Huët anomaly can be an early feature of myelodysplasia.
Although the finding itself is rare, MGDA can be associated with midline cranial defects and abnormal carotid circulation, such as carotid stenosis/aplasia or progressive vascular obstruction with collateralization (also known as moyamoya disease). The vascular defects may lead to ischemia, stroke, or seizures and so a finding of MGDA should be further investigated with radiographic imaging.