Siblings with fucosidosis.

Fucosidosis is a rare lysosomal storage disorder due to deficiency of fucosidase enzyme, with around 100 cases reported worldwide. Here, we describe the clinical and imaging features in two siblings with fucosidosis. An 8-year-old girl presented with global developmental delay, followed by regression of acquired milestones from 3 years of age with bipyramidal, extrapyramidal involvement, coarse facies, telangiectatic lesions, dysostosis multiplex, characteristic magnetic resonance imaging finding along with undetectable levels of the fucosidase activity, which confirmed the diagnosis. Younger sibling has mild developmental delay with autistic traits with no neuroregression until now. He also has undetectable level of fucosidase enzyme activity and is being considered for stem cell transplantation. New case reports would expand the clinical spectrum, early diagnosis and help formulating appropriate therapy. Early diagnosis is crucial and hence sibling screening can be done, and those in the presymptomatic stage can undergo hematopoietic stem cell transplantation, which is potentially curable.

Introduction

Fucosidosis is a rare lysosomal storage disorder, which is inherited in autosomal recessive pattern due to deficient activity of the enzyme alpha L fucosidase. Type I presents in infancy with a very rapid progression of illness and death in early childhood, whereas type II presents later with lesser severity although it is gradually progressive, and sometimes people survive into adulthood.[12] So far around 100 cases have been reported worldwide with only one case from India. Here, we present two siblings with fucosidosis with characteristic clinical, radiological and laboratory features with a brief review of the literature.

Case Report

An 8-year-old girl presented with features of neuroregression from around 3 years of age. She did not have any adverse perinatal events. Her developmental milestones were delayed in all domains (social smile - 3 months, head control - 5 months, rolling over - 8 months and walking unassisted and stranger awareness - 2 years). She had steady developmental gains till 3 years of age after which she developed insidious onset global regression of her acquired milestones. There was no history of seizures, myoclonic jerks, visual or hearing insufficiency.

She presented to us at 8 years of age in bed bound state with spasticity and generalized dystonia. She had lost her language skills and currently indicates toilet needs and makes sounds without any meaningful words. She still retains attachment to family members. She had coarse facies, widened wrist, knee and ankle contractures. She had elevated telangiectatic lesions on her palms and soles [Figure 1a], which was noticed from 7 years of age. Her ophthalmological examination was normal. Her younger sibling, a 3-year-old girl, who was delivered preterm has mild developmental delay with autistic traits and mild coarse facies, but has been having good gains with developmental stimulation. Until now, she has no signs of neuroregression or skin lesions.

Figure 1

(a) Sole of the foot of a child showing multiple elevated telangiectatic lesions. (b-e) Dysostosis multiplex. Widening of the medial end of clavicles (b), deficiency of the medial end of radial epiphysis (c), inferior beaking of thoraco lumbar vertebrae (d), widening of the acetabulum (e)

Her blood counts, liver and renal functions were normal. Ultrasound abdomen revealed no organomegaly. Metabolic workup (lactate, ammonia, aminoacidogram and organic acids) was normal. 24 h urinary collection for mucopolysaccharides was normal. Nerve conduction study and evoked potentials were normal.

X-rays [Figure 1b–e] showed widening of medial ends of clavicles, deficiency of medial part of radial epiphysis, inferior beaking of thoracolumbar vertebrae and widening of acetabulum. Magnetic resonance imaging (MRI) brain revealed features of hypomyelination with diffuse T2-weighted hyperintensity in subcortical and periventricular cerebral white matter. Globus pallidus (GP), substantia nigra and thalamus were hypointense in T2-weighted images, and T1 showed hyperintensity of the GP [Figure 2a–d]. There were two hyperintense curvilinear streaks within the lentiform nucleus on T2-weighted images corresponding to the lateral and medial medullary lamina of the GP [Figure 3]. Computed tomography sections done did not show any calcifications in the GP. Skin biopsy of the lesion from soles showed telangiectasia. Her sweat chloride assay was normal.

Figure 2

Magnetic resonance imaging brain T2-weighted axial image showing hypointensity of globus pallidus bilaterally and the subcortical hyperintensity (a), T1-weighted axial image is showing the hyperintensity of globus pallidi (b), T2 fluid attenuated inversion recovery images shows hypointensity of globus pallidi and hyperintensity of subcortical white matter (c), T2 axial image showing the hyperintensity of subcortical U fibers and deep cerebral white matter suggestive of hypomyelination (d)

Figure 3

T2 coronal sections showing the hyperintensity of medial and lateral medullary lamina of the globus pallidi

The clinical picture of neuroregression, spasticity, dystonia, coarse facies, dysostosis multiplex, telangiectasia, MRI feature of hypomyelination with T2 hypointense and T1 hyperintense GP and substantia nigra was suggestive of fucosidosis. Fucosidase enzyme activity could not be detected in the leukocytes, which confirmed the diagnosis of fucosidosis. The younger sibling also had undetectable enzyme activity.

Discussion

Fucosidosis was first described by Durand et al. (1969).[3] The lack of alpha L fucosidase in these patients was described later. The defect leads to intracellular accumulation of fucose containing glycolipids and glycoproteins in various organs leading to the clinical manifestations. The clinical picture consists of progressive mental and motor deterioration, coarse facies, recurrent infections, dysostosis multiplex, angiokeratoma corporis diffusum, visceromegaly and seizures.[4] Our patient had coarse facies, dysostosis multiplex, telangiectatic skin lesions, (which later evolve into angiokeratomas), progressive mental and motor deterioration. Some authors have differentiated mild and severe forms, representing a continuous clinical spectrum.[4] Our patients probably had a milder form with slow progression, yet had developmental delay noticed from early infancy.

Classical MRI finding described in fucosidosis include hypomyelination and demyelination with hyperintensity on T1 and marked hypointensity on T2-weighted images in the GP, diffuse symmetric T2 W hyperintensity of bilateral subcortical and deep white matter.[5] The reason for signal alteration in GP is not exactly known, although several postulates like calcification, iron, manganese, cerebral glycolipid and triglyceride accumulation has been proposed. Our patient had classical MRI finding, in addition to that our case had T2-weighted hyperintensity of medial and lateral medullary lamina of GP, which passes between the hypointense GP. This finding has been very rarely described in the literature.[6] Characteristic magnetic resonance spectroscopy findings reported are reduced N-acetyl aspartate/choline with elevated choline/creatine ratios and myoinositol, and a specific spectral peak at 3.8-3.9 ppm.[7] Various forms of dysostosis multiplex has been described, which was noted in our case also.[8]

Our case had coarse facies with sociocognitive and motor regression, telangiectatic lesions in palms and soles, dysostosis multiplex and characteristic MRI features of hypomyelination with GP and substantia nigra hypointensity in T2-weighted images and hyperintensity in T1 images with an undetectable fucosidase enzyme activity in leukocytes. The enzymes levels were not detected in her younger sibling also who has developmental delay with autistic traits. Since she is early in the course of illness, she has been referred for consideration of hematopoietic stem cell transplantation. The treatment options at present are limited to hematopoietic stem cell transplant, which has shown to be curative in anecdotal studies.[9] Willems et al. have described 22 disease causing mutations in FUCA 1 gene, located on the short arm of chromosome 1, which included point mutations, deletions, insertions, missense and inactivating mutations.[10] Genetic workup was not done in our patient since it not available in India.

Conclusion

Fucosidosis is a rare lysosomal storage disorder with autosomal recessive inheritance. Characteristic constellation of physical and radiological findings leads clue to the diagnosis. Early identification might lead to screening of presymptomatic siblings who might potentially be offered stem cell transplantation, which could be curative if done at an appropriate age.