dysostosis multiplex

Fucosidosis

Clinical Characteristics
Ocular Features: 

Retinal and conjunctival vessels may appear tortuous, dilated, and irregular in diameter, characteristics sometimes seen in Fabry disease.  Diffuse opacities may be seen in the superficial cornea but do not have the whorl-like pattern seen in Fabry disease.  The majority of ocular cells contain cytoplasmic, membrane-bound aggregates of fibrillogranular and multilaminated material.  The orbits may be shallow as a result of bony dysplasia of the cranial bones. 

Systemic Features: 

The coarse facial features have been described as "Hurler-like".  Two major types have been described: type 1 with onset in the first 6 months of life and rapid psychomotor and general neurologic deterioration, and the later onset, less severe type 2 in which angiokeratomas resembling Fabry disease occur.  Infants with type 1 may not survive beyond one year of age.  The Hurler-like face is less pronounced and the neurologic deterioration is less rapid in type 2 with survival often into the third decade or later.  The intracellular accumulation of glycolipids and glycoproteins leads to cell death accounting for the progression of CNS disease.   Abnormal bone growth (dysostosis multiplex) can lead to short stature.  Elevated sweat NaCl, hypohidrosis, and poor temperature control can be a feature of both types but this is more pronounced in type 1.  The DNA mutation is the same in both types and there may be overlap in some of the clinical features.  Furthermore, both types have been reported in the same family.

Low levels of alpha-L-fucosidase can be detected in plasma, urine, and leukocytes.  Glycolipids and glycoproteins have also been shown to accumulate in the cells of the skin, liver, spleen, pancreas and kidneys. 

Genetics

Fucosidosis is a rare, progressive, autosomal recessive, lysosomal storage disease in which fucose accumulates in tissue as a result of defective alpha-L-fucosidase.  The responsible mutations are found in the FUCA1 gene (1p34). 

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

No treatment is available for the primary disease.  A multidisciplinary supportive program can be beneficial for some patients.  Respiratory therapy especially is important to reduce the threat of infections.

References
Article Title: 

Fucosidosis revisited: a review of 77 patients

Willems PJ, Gatti R, Darby JK, Romeo G, Durand P, Dumon JE, O'Brien JS. Fucosidosis revisited: a review of 77 patients. Am J Med Genet. 1991 Jan;38(1):111-31. Review.

PubMed ID: 
2012122

Maroteaux-Lamy Syndrome (MPS VI)

Clinical Characteristics
Ocular Features: 

Corneal clouding is the cardinal ocular feature and is often visible by 5 years of age.  Several adult patients have had glaucoma with both open and closed angles.  The mechanism is unknown.  Optic nerve compression or secondary edema can cause a relatively sudden loss of vision.

Systemic Features: 

The lysosomal accumulation of glycosaminoglycans is responsible for the widespread signs and symptoms found in this disease.  Bone destruction in shoulders, hips and skull is often seen by the second decade of life and may become evident later in the knees and spine.  Early growth may be normal but eventually slows resulting in short stature.  Dysplasia of bones comprising these joints leads to stiffness and restricted movement.  The face is dysmorphic with coarse features.  Bone dysplasia and facial dysmorphism may be seen at birth.  Myelopathy and even tetraplegia can result from vertebral compression.  Intelligence is often normal although more severely affected individuals may have some cognitive defects.  Hepatosplenomegaly is common and compromised respiratory function can result in reduced physical stamina.  The tongue is usually enlarged.  Accumulation of dermatan sulfate in heart valves may produce insufficiency or restriction of outflow.

Genetics

MPS VI is a lysosomal storage disease inherited in an autosomal recessive pattern.  The responsible mutations lie in ARSB (5q11-q13), the gene that encodes the enzyme arylsulfatase B.  The phenotype results from defective dermatan sulfate breakdown with lysosomal accumulation.

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

Enzyme replacement therapy with galsulfase (Naglazyme®) is beneficial in alleviating some of the manifestations of this disease.  Orthopedic surgery for specific deformities may be necessary.  Visually significant corneal opacification may require corneal transplantation.

References
Article Title: 

Threshold effect of urinary glycosaminoglycans and the walk test as indicators of disease progression in a survey of subjects with Mucopolysaccharidosis VI (Maroteaux-Lamy syndrome)

Swiedler SJ, Beck M, Bajbouj M, Giugliani R, Schwartz I, Harmatz P, Wraith JE, Roberts J, Ketteridge D, Hopwood JJ, Guffon N, S?deg Miranda MC, Teles EL, Berger KI, Piscia-Nichols C. Threshold effect of urinary glycosaminoglycans and the walk test as indicators of disease progression in a survey of subjects with Mucopolysaccharidosis VI (Maroteaux-Lamy syndrome). Am J Med Genet A. 2005 Apr 15;134A(2):144-50.

PubMed ID: 
15690405
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