coarse facies

The overall facial appearance may resemble Cornelia de Lange syndrome with hypertrichosis and a coarse, round facies.  Head circumference is low normal.  Septal defects and a patent ductus arteriosus are often present.  Laryngeal and tracheal malacia predispose to recurrent pulmonary infections and chronic lung disease.  Skeletal dysplasia includes brachydactyly and anomalous vertebral bodies resulting in short stature (3^rd percentile).  Genitourinary abnormalities include cryptorchidism, horseshoe kidney, and vesiculoureteral reflux.  Delayed gastric emptying and reflux have been reported.

Mannosidosis is a highly variable multisystem disorder.  Onset may be in infancy but in other patients symptoms appear later in the first decade.  Progression of disease is more rapid in individuals with early onset (type 3) with rapid mental, motor deterioration and early death.  The characteristic coarse facial features usually are evident later in milder cases (types 1 and 2) that have mild or moderate intellectual disabilities.  Regardless, mannosidosis is relentlessly progressive with mental deterioration and motor disabilities.  Ataxia is a common feature.  Dental anomalies (diastema), large ears, macroglossia, joint stiffness,, hepatosplenomegaly, enlarged head circumference, hearing loss (sensorineural), increased susceptibility to infections, dysarthria, and spondylolysis may be present.

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. 

This is a neurodegenerative disorder with progressive deterioration of muscle and central nervous system functions.  Myoclonus, mental deterioration, hepatosplenomegaly, muscle weakness and atrophy are common.  The defect in neuraminidase activity leads to abnormal amounts of sialyl-oligosaccharides in the urine.  Spinal deformities such as kyphosis are common.  Deep tendon reflexes are exaggerated.  Ataxia and hearing loss may be present.  Coarse facies, a barrel chest, and short stature are characteristic.  Hepatic cells contain numerous vacuoles and numerous inclusions.

Sialidosis types I and II are both caused by mutations in the neuroaminidase gene.  Type I is associated with milder disease than type II which has an earlier age of onset and may present in infancy or even begin in utero.  Early death within two years of age is common in the congenital or infantile forms.  There is, however, significant variability in age of onset and the course of disease among types. 

Sandoff disease may be clinically indistinguishable from Tay-Sachs disease even though the same enzyme is defective (albeit in separate subunits A and B that together comprise the functional hexosaminidase enzyme).   The infantile form of this lysosomal storage disease is the most common.  Infants appear to be normal until about 3-6 months of age when neurological development slows and muscles become weak.  Seizures, loss of interest, and progressive paralysis begin after this together with loss of vision and hearing.  The facies are coarse and the tongue is enlarged.  An exaggerated startle response is considered an early and helpful sign in the diagnosis.  Hepatosplenomegaly is usually not present.  Among infants with early onset disease, death usually occurs by 3 or 4 years of age.     

Ataxia with spinocerebellar degeneration, motor neuron disease, and progressive dystonia are more common in individuals with later onset of neurodegeneration.  The juvenile and adult-onset forms of the disease also progress more slowly.

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.