Widespread Vasculopathy in a Patient with Morquio A Syndrome

Tracheal narrowing in children and adults with mucopolysaccharidosis type IVA: evaluation with computed tomography angiography

BACKGROUND

Mucopolysaccharidosis type IVA (MPS IVA) is characterized by progressive skeletal dysplasia and respiratory issues with difficult airway management during anesthesia.

OBJECTIVE

To characterize tracheal abnormalities in children and adults with MPS IVA including interplay of the trachea, vasculature, bones and thyroid at the thoracic inlet.

MATERIALS AND METHODS

Computed tomography (CT) angiograms of the chest were analyzed for trachea shape, narrowing and deviation at the thoracic inlet, course of vasculature, bone alignment and thyroid location. The tracheal cross-sectional area was measured at the cervical, thoracic inlet and intrathoracic levels.

RESULTS

Thirty-seven patients (mean age: 18.1 years) were included. The mean tracheal cross-sectional area narrowing at the thoracic inlet was 63.9% (range: -2.1-96%), with a trend for increased tracheal narrowing in older children. The trachea was commonly deviated rightward posterior (22/37, 59%). T- or W-shaped tracheas had two times greater tracheal narrowing than D- or U-shaped tracheas (P<0.05). The brachiocephalic artery was tortuous in 35/37 (95%) with direct impingement on the trachea in 24/37 (65%). No correlation was observed between bony thoracic inlet diameter and tracheal narrowing. The thyroid was located in the thoracic inlet in 28/37 (76%) cases, significantly associated with tracheal narrowing (P=0.016).

CONCLUSION

Narrowing, deviation and abnormal shape of the trachea at the thoracic inlet are common in children and adults with MPS IVA, with a trend toward increased narrowing with advancing age in children. A W- or T-shaped trachea is associated with focal tracheal narrowing. Crowding of the thoracic inlet, due to vascular tortuosity and thyroid position, appears to play a major role.

Proteoglycan (Keratan Sulfate) Barrier in Developing Human Forebrain Isolates Cortical Epileptic Networks From Deep Heterotopia, Insulates Axonal Fascicles, and Explains Why Axosomatic Synapses Are Inhibitory

Axons from deep heterotopia do not extend through U-fibers, except transmantle dysplasias. Keratan sulfate (KS) in fetal spinal cord/brainstem median septum selectively repels glutamatergic axons while enabling GABAergic commissural axons. Immunocytochemical demonstration of KS in neocortical resections and forebrain at autopsy was studied in 12 fetuses and neonates 9-41 weeks gestational age (GA), 9 infants, children, and adolescents and 5 patients with focal cortical dysplasias (FCD1a). From 9 to 15 weeks GA, no KS is seen in the cortical plate; 19-week GA reactivity is detected in the molecular zone. By 28 weeks GA, patchy granulofilamentous reactivity appears in extracellular matrix and adheres to neuronal somata with increasing intensity in deep cortex and U-fibers at term. Perifascicular KS surrounds axonal bundles of both limbs of the internal capsule and within basal ganglia from 9 weeks GA. Thalamus and globus pallidus exhibit intense astrocytic reactivity from 9 weeks GA. In FCD1a, U-fiber reactivity is normal, discontinuous or radial. Ultrastructural correlates were not demonstrated; KS is not electron-dense. Proteoglycan barrier of the U-fiber layer impedes participation of deep heterotopia in cortical epileptic networks. Perifascicular KS prevents aberrant axonal exit from or entry into long and short tracts. KS adhesion to neuronal somatic membranes may explain inhibitory axosomatic synapses.

Natural history of the oldest known females with mucopolysaccharidosis type IVA (Morquio A syndrome)

Mucopolysaccharidosis Type IVA (MPS IVA), also known as Morquio A syndrome, is an autosomal recessive lysosomal storage disorder that results from variants in the GALNS gene that encodes the enzyme galactosamine-6-sulfate sulfatase. This syndrome has systemic manifestations including, but not limited to, musculoskeletal, respiratory, cardiovascular, rheumatologic, neurologic, dental, ophthalmologic, and otologic. This condition is usually detected within the first few years of life with an average life expectancy of 25.3 ± 17.43 years. We report the natural history of two of the oldest known females with MPS IVA, who were each clinically diagnosed at 4 years of age and who are now 74 and 70 years of age, respectively. They are both affected by pathogenic variants c.319G>A (p.Ala107Thr) and c.824 T>C (p.Leu275Pro) in the GALNS gene.