Introduction
Traboulsi syndrome is an autosomal recessive disorder characterized by displaced crystalline lenses, anterior-segment anomalies, and, in certain cases, non-traumatic conjunctival cysts. The face has a characteristic look, with a flattened malar region and a convex nasal ridge. The disorder is known to be caused by mutations in the aspartate beta-hydroxylase (ASPH) gene.
What Is the Occurrence of Traboulsi Syndrome?
Researchers present seven more people with distinctive ocular and facial traits from six unrelated families. Five people had aortic root dilatation, some of which began in childhood, and one had aortic root surgery at the age of 47 for severe aortic regurgitation and aortic root dilatation. Surprisingly, inguinal hernias were often reported.
Some skeletal traits were observed. However, they needed to be more consistent. Traboulsi Syndrome is uncommon, occurring in just one in one million births. The disease was originally documented in a consanguineous Lebanese family in 1995, affecting six family members over three generations, mostly from the Lebanese Druze group. Additional cases of the unusual disease have been reported in India, Saudi Arabia, Persia, Pakistan, and China.
What Is the Cause of Traboulsi Syndrome?
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Traboulsi syndrome is assumed to be autosomal or autosomal recessive but pseudodominantly inherited.
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The genetic anomaly was discovered to result from the inheritance of two ASPH gene variations on chromosome 8q12.1.
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The ASPH protein has a C-terminal catalytic domain that catalyzes the posttranslational hydroxylation of aspartic acid and asparagine residues inside many proteins' Epidermal Growth Factor (EGF)--like domains.
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Many genes that produce Mendelian diseases related to lens dislocation have EGF domains.
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Several unique gene variations, including missense and nonsense mutations, have been reported concerning Traboulsi syndrome.
What Is the Significance of Traboulsi Syndrome?
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Patel et al. (2014) hypothesized that lens dislocation is caused by disrupted EGF hydroxylation.
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Because of permanent trabecular meshwork damage, decreased lens stability may result in anterior subluxation of the lens, anterior displacement of the iris, closed iridocorneal angles, increased corneal scarring and opacity, and increased intraocular pressure.
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As aqueous humor runs via fistulas linking the anterior chamber to the subconjunctival region, the increased intraocular pressure and scleral thinning may result in the distinctive spontaneous filtering blebs seen in this disease.
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Some features, such as ectopia lentis and spontaneous pneumothorax, appear to overlap with Marfan syndrome, which is caused by any of multiple FBN1 gene mutations that cause FBN1 function to be decreased.
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As previously stated, the FBN1 protein has an EGF domain and may have reduced functioning in Traboulsi syndrome due to a lack of EGF hydroxylation produced by an ASPH gene mutation.
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This might explain some similarities in clinical symptoms between Marfan syndrome and Traboulsi syndrome and give an example of overlapping clinical aspects between this condition and other disorders.
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Senthil et al. (2021) also discovered two gene variations in three Traboulsi syndrome patients.
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They discovered that the two people with a particular gene mutation had cardiac problems, but the others did not.
How Is the Traboulsi Syndrome Diagnosed?
Traboulsi syndrome is clinically diagnosed based on a unique mix of ophthalmologic and craniofacial characteristics. Due to the many similarities with different disease processes, genetic testing may be undertaken to confirm the diagnosis. Patients may have a lengthy history of vision impairment, which commonly begins in infancy or adolescence, as well as corneal haze or scarring. Patients frequently report no eye trauma or illness history to explain their symptoms.
Although systemic signs of cardiac or pulmonary abnormalities have been linked to the disease, they are not essential for a diagnosis. They are not considered to be common in this population. These individuals frequently report a family history of eye diseases or vision impairment. Slit-lamp microscopy of the anterior chamber, conjunctiva, sclera, applanation tonometry, and visual inspection of the eyes and facial structure are all part of a thorough eye examination.
A general medicine doctor may perform a targeted physical examination to avoid additional problems. This targeted examination may involve cardiac and pulmonary auscultation to look for heart murmurs, arrhythmias, and irregular or reduced breath sounds. Inspecting the skeletal system may uncover signs such as pectus deformity and hypermobile joints.
How Is Traboulsi Syndrome Treated?
Patients with Traboulsi syndrome must be continuously watched for symptomatic treatment of glaucoma and corneal illness and for ophthalmologists to evaluate when and how surgical intervention should be undertaken due to its gradual and complicated pathophysiology. To Co-manage any additional systemic signs, a range of ophthalmologic experts may be contacted, including glaucoma, cornea, pediatrics, and genetic, cardiac, and pulmonary specialists. Although many cases of ectopia lentis can be managed with adequate spectacle or contact lens correction rather than surgery, the lens subluxation and related ocular sequelae in Traboulsi syndrome are progressive and appear to deteriorate without surgery. As a result, surgical intervention is frequently necessary for successful therapy.
Medical therapy is largely used to treat the symptoms of corneal manifestations and glaucoma. Regular medical check-ups are advised to avoid increasing glaucoma and corneal symptoms. Lens subluxation is managed surgically by lensectomy, followed by gas-permeable contact lenses.
Early lensectomy also helps to prevent irreparable corneal and trabecular meshwork damage caused by persistently closed iridocorneal angles. As a result, lensectomy is now indicated after lens subluxation is found, which is most commonly reported in youth to early adulthood. However, Awais et al. discovered from their experience that incisional surgical techniques do not lead to a better long-term prognosis once the eyes have gone into hypotony and a filtration bleb has fully developed, probably because of a weaker scleral coat.
In one case report, a patient with corneal decompensation received penetrating keratoplasty instead of lensectomy. This method avoids the complications of lensectomy, such as an untreatable persistent aqueous leak.
Good surgical results were reported when topical steroids frequent intraocular pressure and fundus monitoring followed surgery. Spectacles may be prescribed after surgery to improve eye acuity. A patient with Traboulsi syndrome had unintentional filtering blebs at the sites of several sclerotomies several years after surgery.
Furthermore, as previously indicated, lensectomy in a patient with corneal decompensation may result in a persistent aqueous leak due to blebs and scleral thinning. As a result, before surgery, alternate operations or methods to lensectomy, sclerotomies, or other invasive treatments should be examined. Visual prognosis varies depending on the timing of diagnosis and care of ocular diseases, although visual acuity is often poor.
Conclusion
Traboulsi syndrome is an exceedingly uncommon autosomal recessive illness characterized by facial dysmorphia, lens displacement, anterior-segment abnormalities, spontaneous filtering blebs, and sometimes systemic signs caused by multiple Aspartate/asparagine-hydroxylase (ASPH) gene variations. Although genetic testing may be conducted to validate the genotype linked with its specific manifestation, this disorder is generally diagnosed clinically. This disorder has no cure, although medicinal, optical, and surgical therapies are available to reduce related corneal manifestations and glaucoma symptoms. Though visual acuity is often poor, the prognosis varies depending on the time of diagnosis and care.
