GAPO syndrome with pansutural craniosynostosis leading to intracranial hypertension

GAPO syndrome: a novel variant in ANTXR1 gene

BACKGROUND

GAPO syndrome is a rare autosomal recessive disorder characterized by the acronym of growth retardation, alopecia, pseudo-anodontia and progressive optic atrophy. While the genetic alteration of the ANTXR1 gene has been known for its cause, the full range of its clinical and genetic manifestations is not well explored due to the syndrome's extreme rarity.

MATERIALS/METHODS

We report two children born to a non-consanguineous parent in India with classical features of GAPO syndrome. The whole exome sequencing analysis (WES) was performed in both siblings, and the parent's genetic and clinical status was determined. The identified variation was characterized in silico using homology-based protein modelling.

RESULTS

In WES analysis, a homozygous ANTXR1 gene indel variant c. 151_152 + 2delAAGT (p.Lys51fs) was identified in both siblings. The parents were identified as the carriers of the ANTXR1 variant. Additionally, they also displayed mild GAPO-related facial and glaucomatous features. In silico analysis and homology-based ANTXR1 protein structure illustrate a frameshift and the subsequent premature truncation of the protein.

CONCLUSIONS

Our reports contribute to the comprehension of GAPO syndrome within the Indian context describing an ANTXR1 novel variant causing premature protein truncation. WES-based genetic testing can significantly aid in expertly diagnosing GAPO syndrome. In the present case scenario, a variable penetrance of ANTXR1 variation was acknowledged as the carrier parents also had a mild degree of GAPO-related features. Future reports that include parental clinical diagnosis can offer further insights in this context.

Prenatal onset GAPO syndrome with a novel ANTXR1 variant in an Indian child: Expansion of the phenotype & literature review

GAPO syndrome is a rare genetic condition caused by bi-allelic variants in ANTXR1 gene & is an abbreviation for its core features - growth retardation, alopecia, pseudo-anodontia & optic atrophy. Certain additional features involving various other systems have been reported over the years & contribute to the expanding spectrum of this evolving phenotype. We report GAPO syndrome in a 3.75 year old Indian female child, who presented with some unique features such as sagittal craniosynostosis with scaphocephaly & bilateral choroid plexus cysts, alongside the core phenotype. We also report a novel frameshift variant in our patient & offer first evidence for the prenatal onset of some features.

Two siblings with GAPO syndrome: Ophthalmic presentation and histopathologic findings

BACKGROUND

GAPO syndrome (growth retardation, alopecia, pseudoanodontia, optic atrophy) is a rare, autosomal recessive connective tissue disorder with only 60 reported cases. Ophthalmic manifestations vary and include hypertelorism, optic atrophy, and glaucoma. There have been three reported cases of GAPO syndrome with craniosynostosis.

MATERIALS/METHODS

We describe two new siblings with GAPO syndrome and craniosynostosis and the first histopathologic analysis of Tenon's capsule and extraocular muscle in this syndrome.

RESULTS

Both siblings presented with papilledema and V-pattern strabismus in addition to the alopecia, brittle eyelashes, growth retardation, and pseudoanodontia that characterize GAPO syndrome. Cranial vault expansion, though successful, was complicated by lack of distinct periosteal layers, thin dural adherence to bone, and extensive venous bleeding. Tenons encountered during strabismus surgery was inelastic and highly vascular. Histopathological analysis revealed hyalinization of Tenon's and a thickened, homogenized, amorphous appearance, similar to the extracellular matrix abnormalities described in skin and other organs Histopathological analysis of extraocular muscle was, in contrast, unremarkable.

CONCLUSIONS

GAPO impacts the extracellular matrix of Tenon's resulting in inelasticity and hypervascularity. Ophthalmologists should be mindful of these aberrant characteristics when planning surgery in this population.

GAPO syndrome with craniosynostosis and intracranial hypertension

BACKGROUND

GAPO (growth retardation, alopecia, pseudoanodontia, and optic atrophy) as a rare genetic disorder includes growth retardation, alopecia, pseudoanodontia, and optic atrophy. It was reported to be associated with craniosynostosis and intracranial hypertension.

CASE REPORT

A patient with such a rare disorder associated with multisuture craniosynostosis and headache is presented. Surgery has been done due to intracranial hypertension.

CONCLUSIONS

Abnormal intraoperative findings including sever pericranium and dural adhesions and extraordinary bleeding related to this syndrome are described.

GAPO syndrome in seven new patients: Identification of five novel ANTXR1 mutations including the first large intragenic deletion

GAPO syndrome is a very rare disorder characterized by growth retardation, alopecia, pseudoanodontia and progressive optic atrophy. It is caused by biallelic mutations in the ANTXR1 gene. Herein, we describe the clinical and molecular findings of seven new patients with GAPO syndrome. Our patients presented with the characteristic clinical features of the syndrome except for one patient who did not display total alopecia till the age of two years. Strikingly, optic atrophy and glaucoma were observed in all patients and one patient showed keratopathy in addition. Moreover, craniosynstosis was an unusual associated finding in one patient. Mutational analysis of ANTXR1 gene identified five novel homozygous mutations including two frameshift, two splice site and a large intragenic deletion of exon 3. Our results reinforce the clinical characteristics of the syndrome, expand the mutational spectrum and provide more insights into the role of the ANTXR1 protein in the regulation of extracellular matrix.