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Overview of Lysosomal Storage Disorders

By

Matt Demczko

, MD, Sidney Kimmel Medical College of Thomas Jefferson University

Last full review/revision Apr 2020| Content last modified Apr 2020
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Topic Resources

Lysosomal enzymes break down macromolecules, either those from the cell itself (eg, when cellular structural components are being recycled) or those acquired outside the cell. Inherited defects or deficiencies of lysosomal enzymes (or other lysosomal components) can result in accumulation of undegraded metabolites. Because there are numerous specific deficiencies, storage diseases are usually grouped biochemically by the accumulated metabolite. Subgroups include

The most important are the mucopolysaccharidoses and sphingolipidoses. Type 2 glycogenosis is a lysosomal storage disorder, but most glycogenoses are not.

Because reticuloendothelial cells (eg, in the spleen) are rich in lysosomes, reticuloendothelial tissues are involved in a number of lysosomal storage disorders, but, generally, tissues richest in the substrate are most affected. Thus the brain, which is rich in gangliosides, is particularly affected by gangliosidoses, whereas mucopolysaccharidoses affect many tissues because mucopolysaccharides are present throughout the body.

Mucopolysaccharidoses (MPS)

MPS are inherited deficiencies of enzymes involved in glycosaminoglycan breakdown. Glycosaminoglycans (previously termed mucopolysaccharides) are polysaccharides abundant on cell surfaces and in extracellular matrix and structures. Enzyme deficiencies that prevent glycosaminoglycan breakdown cause accumulation of glycosaminoglycan fragments in lysosomes and cause extensive bone, soft tissue, and central nervous system changes. Inheritance is usually autosomal recessive (except for MPS type II).

Age at presentation, clinical manifestations, and severity vary by type (see table Mucopolysaccharidosis (MPS)). Common manifestations include coarse facial features, neurodevelopmental delays and regression, joint contractures, organomegaly, stiff hair, progressive respiratory insufficiency (caused by airway obstruction and sleep apnea), cardiac valvular disease, skeletal changes, and cervical vertebral subluxation.

Diagnosis of mucopolysaccharidoses is suggested by history, physical examination, bone abnormalities (eg, dysostosis multiplex) found during skeletal survey, and elevated total and fractionated urinary glycosaminoglycans. Diagnosis is confirmed by DNA analysis and/or enzyme analysis of cultured fibroblasts (prenatal) or peripheral white blood cells (postnatal). (Also see testing for suspected inherited disorders of metabolism.) Additional testing is required to monitor organ-specific changes (eg, echocardiography for valvular disease, audiometry for hearing changes).

Treatment of mucopolysaccharidosis type I is enzyme replacement with laronidase, which effectively halts progression and reverses all non-central nervous system complications of the disease. Hematopoietic stem cell (HSC) transplantation has also been used. The combination of enzyme replacement and HSC transplantation is under study. For patients with MPS type IV-A (Morquio A syndrome), enzyme replacement with elosulfase alfa may improve functional status, including mobility.

Table
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Mucopolysaccharidosis (MPS)

Disease (OMIM Number)

Defective Proteins or Enzymes

Comments

MPS IH (Hurler syndrome; 607014*)

MPS IS (Scheie syndrome; 607016*)

MPS IH/S (Hurler-Scheie syndrome; 607015*)

Alpha-L-iduronidase

Onset: In IH, 1st year

In IS, > 5 years

In IH/S, 3–8 years

Urine metabolites: Dermatan sulfate, heparin sulfate

Clinical features: Corneal clouding, stiff joints, contractures, dysostosis multiplex, coarse facies, coarse hair, macroglossia, organomegaly, intellectual disability with regression, valvular heart disease, hearing and vision impairment, inguinal and umbilical hernia, sleep apnea, hydrocephalus

Treatment: Supportive care, enzyme replacement with laronidase, stem cell or bone marrow transplantation

MPS II (Hunter syndrome; 309900*)

Iduronate sulfate sulfatase

Onset: 2–4 years

Urine metabolites: Dermatan sulfate, heparin sulfate

Clinical features: Similar to Hurler syndrome but milder and no corneal clouding

In mild form, normal intelligence

In severe form, progressive intellectual and physical disability, death before age 15

Treatment: Enzyme replacement (idursulfase), supportive care, stem cell or bone marrow transplantation

MPS III (Sanfilippo syndrome)

Onset: 2–6 years

Urine metabolites: Heparin sulfate

Clinical features: Similar to Hurler syndrome but with severe intellectual disability and mild somatic manifestations

Treatment: Supportive care

Type IIIA (252900*)

Heparan N-sulfatase

Type IIIB (252920*)

Alpha-N-acetylglucosaminidase

Type IIIC (252930*)

Acetyl CoA:alpha-glucosaminide acetyltransferase

Type IIID (252940*)

N-acetylglucosaminine-6-sulfatase

MPS IV (Morquio syndrome

Onset: 1–4 years

Urine metabolites: Keratin sulfate; in IVB, also chondroitin 6-sulfate

Clinical features: Similar to Hurler syndrome but with severe bone changes including odontoid hypoplasia; possibly normal intelligence

Treatment: Supportive care

For type IVA, enzyme replacement therapy with elosulfase alfa

Type IVA (253000*)

Galactosamine-6-sulfate sulfatase

Type IVB (253010*)

Beta-galactosidase

MPS VI (Maroteaux-Lamy syndrome; 253200*)

N-Acetylgalactosamine-4sulfatase (arylsulfatase B)

Onset: Variable but can be similar to Hurler syndrome

Urine metabolites: Dermatan sulfate

Clinical features: Similar to Hurler syndrome but normal intelligence

Treatment: Enzyme replacement with galsulfase, supportive care

MPS VII (Sly syndrome; 253220*)

Beta-glucuronidase

Onset: 1–4 years

Urine metabolites: Dermatan sulfate, heparan sulfate, chondroitin 4-sulfate, chondroitin 6-sulfate

Clinical features: Similar to Hurler syndrome but greater variation in severity

Treatment: Supportive care, stem cell or bone marrow transplantation

MPS IX (hyaluronidase deficiency; 601492*)

Hyaluronidase

Onset: 6 months

Urine metabolites: None

Clinical features: Bilateral soft-tissue periarticular masses, dysmorphic features, short stature, normal intelligence

Treatment: Not established

* For complete gene, molecular, and chromosomal location information, see the Online Mendelian Inheritance in Man® (OMIM®) database.

Sphingolipidoses

Sphingolipids are normal lipid components of cell membranes; they accumulate in lysosomes and cause extensive neuronal, bone, and other changes when enzyme deficiencies prevent their breakdown. Although incidence is low, carrier rate of some forms is high.

There are many types of sphingolipidosis (see table Some Sphingolipidoses); the most common sphingolipidosis is

Others sphingolipidoses include

Table
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Some Sphingolipidoses

Disease (OMIM Number)

Defective Proteins or Enzymes

Comments

GM1 gangliosidosis, generalized

Ganglioside beta-galactosidase

Type I (infantile type; 230500*)

Type I onset: 0–6 months

Urine metabolites: None

Clinical features: Coarse facies; clear cornea, cherry-red macular spot, gingival hyperplasia, organomegaly, dysostosis multiplex, hypertrichosis, angiokeratoma corporis diffusum, cerebral degeneration; death in infancy

Treatment: Supportive care

Type II (juvenile type; 230600*)

Type II onset: 6–12 months

Urine metabolites: None

Clinical features: Gait disturbance, spasticity, dystonia, loss of psychomotor milestones, mild visceromegaly and bone abnormality

Treatment: Supportive care

Type III (adult type; 230650*)

Type III onset: 3–50 years

Urine metabolites: None

Clinical features: Angiokeratoma corporis diffusum, spondyloepiphyseal dysplasia, dysarthria, cerebellar dysfunction; no macular red spots or visceromegaly

Treatment: Supportive care

GM2 gangliosidosis

Onset: In types I and II, 5–6 months

In type III, 2–6 years

Urine metabolites: None

Clinical features: Doll-like facies; cherry-red retina; early blindness; exaggerated startle reflex; initial hypotonia followed by hypertonia; psychomotor retardation followed by regression, seizures, and impaired sweating; in types I and II, death by age 5 years; death later in type III

In type I, increased frequency in Ashkenazi Jews

Treatment: Supportive care

Type I (Tay-Sachs disease; 272800*)

Beta-hexosaminidase A

Type II (Sandhoff disease; 268800*)

Beta-hexosaminidase B

Type III (juvenile type)

Beta-hexosaminidase A

GM2 activator protein deficiency (Tay-Sachs disease AB variant, GM2A; 272750*)

GM2 activator protein

Onset, urine metabolites, and clinical features: Similar to Tay-Sachs

Treatment: Supportive care, stem cell or bone marrow transplantation

Niemann-Pick disease (see also Niemann-Pick disease types C and D in table Other Lipidoses)

Sphingomyelinase

Type A (257200*)

Onset:< 6 months

Clinical features: Growth delay, cherry-red retina, frequent respiratory infections, hepatosplenomegaly, vomiting, constipation, osteoporosis, lymphadenopathy, hypotonia followed by spasticity, sea-blue histiocytes on tissue biopsies, large vacuolated foam cells in bone marrow (NP cells), death by age 3 years

Treatment: Supportive care, stem cell or bone marrow transplantation

Type B (607616*)

Onset: Variable

Clinical features: Much milder symptoms, no neurologic involvement, survival to adulthood

Increased frequency in Ashkenazi Jews

Treatment: Supportive care, stem cell or bone marrow transplantation

Glucosylceramide beta-glucosidase

Type I (adult or chronic form; 230800*)

Onset: Childhood to adulthood

Urine metabolites: None

Clinical features: Hepatosplenomegaly, osteolytic lesions with bone pain, avascular necrosis of the femoral head, vertebral compression, thrombocytopenia, anemia

Increased frequency in Ashkenazi Jews

Treatment: Supportive care

Splenectomy

Enzyme replacement (imiglucerase)

Substrate reduction (eliglustat, miglustat)

Bone marrow or stem cell transplantation

Type II (infantile form; 230900*)

Onset: Infancy

Urine metabolites: None

Clinical features: Infantile hydrops, hepatosplenomegaly, dysphagia, bone lesions, hypertonicity, pseudobulbar palsy, laryngeal spasm, ichthyosis, developmental delay, hypersplenism, death by age 2 years

Treatment: Supportive care

Type III (juvenile form, Norrbottnian type; 231000*)

Onset: 4–8 years

Urine metabolites: None

Clinical features: Similar to type II except milder, possible survival into adulthood

Treatment: Supportive care, enzyme replacement (imiglucerase)

Farber disease (lipogranulomatosis; 228000*)

Ceramidase

Onset: First weeks of life

Urine metabolites: Ceramide

Clinical features: Lipogranulomatosis, periarticular subcutaneous nodules, irritability, hoarse cry, psychomotor and growth delay, respiratory insufficiency, histiocytosis in multiple tissues, nephropathy, hepatosplenomegaly, cherry-red macular spot

Milder variants sometimes divided into 7 subtypes according to severity

Treatment: Supportive care

Fabry disease (301500*)

Trihexosylceramide alpha-galactosidase

Onset: Childhood or adolescence

Urine metabolites: Globosylceramide

Clinical features: Painful crisis involving extremities and abdomen precipitated by stress, fatigue, or exercise; angiokeratoma; growth and pubertal delay; corneal dystrophy; renal failure; cardiomyopathy; myocardial infarction and heart failure, hypertension; lymphedema; obstructive lung disease; strokes; seizures; death

Generally, only males affected but occasionally females

Treatment: Supportive care, enzyme replacement (agalsidase beta)

  • Late infantile form

  • Juvenile form

  • Adult form

  • Pseudodeficiency form

Arylsulfatase A

Onset: For late infantile form, 1–2 years

For juvenile form, 4 years to puberty

For adult form, any age after puberty

Urine metabolites: Sulfatides

Clinical features: Optic atrophy, gall bladder dysfunction, urinary incontinence, hypotonia, gait disturbance, hyporeflexia followed by hyperreflexia, bulbar palsies, ataxia, chorea, demyelination and developmental regression, increased cerebrospinal fluid protein

In adult form, also schizophrenia-like symptoms

Pseudodeficiency characterized by mild decrease in enzyme activity without neurologic degeneration

Treatment: Supportive care, consideration of bone marrow or stem cell transplantation in patients who have mildly symptomatic forms

Therapeutic options under investigation, primarily in late infantile forms, include gene therapy, enzyme replacement therapy, substrate reduction therapy, and enzyme enhancement therapy

Mucosulfatidosis (multiple sulfatase deficiency; 272200*)

Sulfatase-modifying factor-1

Onset: Infancy

Urine metabolites: Sulfatides, mucopolysaccharides

Clinical features: Similar to late infantile form of metachromatic leukodystrophy, plus ichthyosis and dysostosis multiplex

Treatment: Supportive care

Krabbe disease (245200*)

  • Infantile form

  • Late infantile form

  • Juvenile form

  • Adult form

Galactosylceramide beta-galactosidase

Onset: In infantile form, 3–6 months

In late infantile and juvenile forms, 15 months–17 years

In adult form, variable

Urine metabolites: None

Clinical features: Growth delay, developmental delay followed by regression, deafness, blindness, vomiting, hyperirritability, hypersensitivity to stimuli, increased deep-tendon reflex, and spasticity; seizures; diffuse cerebral atrophy and demyelination; elevated cerebrospinal fluid protein; peripheral neuropathy; episodic fever

In adult form, mentation generally preserved

Treatment: Supportive care, bone marrow or stem cell transplantation

Sphingolipid activator protein deficiencies

Onset: Infancy to early childhood

Urine metabolites: Sulfatides

Clinical features: In saposin B deficiency, features similar to those of metachromatic leukodystrophy

In saposin C deficiency, features similar to those of Gaucher disease type III

In prosaposin deficiency, features of saposin B and C deficiencies

Treatment: Supportive care; consideration of bone marrow or stem cell transplantation; for features of Gaucher disease, consideration of enzyme replacement

Prosaposin deficiency (176801*)

Prosaposin

Saposin B deficiency (sulfatide activator deficiency)

Saposin B

Saposin C deficiency (Gaucher activator deficiency)

Saposin C

* For complete gene, molecular, and chromosomal location information, see the Online Mendelian Inheritance in Man® (OMIM®) database.

MPS = mucopolysaccharidosis.

Mucolipidoses and other lysosomal disorders

In addition to mucolipidoses, there are many other lysosomal disorders including

Table
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Mucolipidosis (ML)

Disease (OMIM Number)

Defective Proteins or Enzymes

Comments

ML I

See Sialidosis type I in table Oligosaccharidosis and Related Disorders

ML II (I-cell disease; 252500*)

N-Acetylglucosaminyl-1-phosphotransfeerase catalytic subunit

Onset: 1st year of life

Urine metabolites: No mucopolysaccharides

Clinical features: Similar to Hurler syndrome but more severe; presence of phase-dense inclusion bodies in fibroblasts (I-cells)

Treatment: Supportive care

ML III (pseudo-Hurler polydystrophy)

N-Acetylglucosaminyl-1-phosphotransfeerase

Onset: 2–4 years

Urine metabolites: None

Clinical features: Similar to ML II but later onset and possible survival to adulthood

Treatment: Supportive care

Type III-A (252600*)

Catalytic subunit

Type III-C (252605*)

Substrate-recognition subunit

ML IV

See Sialolipidosis in table Oligosaccharidosis and Related Disorders

* For complete gene, molecular, and chromosomal location information, see the Online Mendelian Inheritance in Man® (OMIM®) database.

Table
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Other Lipidoses

Disease (OMIM Number)

Defective Proteins or Enzymes

Comments

Niemann-Pick disease (see also Niemann-Pick disease, types A and B in table Some Sphingolipidoses)

Onset: Highly variable (early or late infancy, adolescence, adulthood)

Urine metabolites: None

Clinical features: Vertical gaze palsy, hepatosplenomegaly, neonatal jaundice, dysphagia, hypotonia followed by spasticity, seizures, cerebellar ataxia, dysarthria, psychomotor delay and degeneration, psychosis and behavioral problem, fetal ascites, foam cells and sea-blue histiocytes as in Niemann-Pick disease types A and B

Earlier onset associated with faster progression and shorter lifespan

Treatment: Substrate reduction (miglustat)

Hematopoietic stem cell transplantation may be effective in young patients with NPC2 mutations

Type C1/Type D (257220*)

NPC1 protein

Type C2 (607625*)

Epididymal secretory protein 1 (HE1; NPC2 protein)

Lysosomal acid lipase deficiency (278000*)

Lysosomal acid lipase

Onset: In Wolman disease, infancy

In CESD, variable

Urine metabolites: None

Clinical features: Growth failure; vomiting; diarrhea; steatorrhea; hepatosplenomegaly; hepatic fibrosis; pulmonary hypertension; adrenal calcification; xanthomatous changes in liver, adrenal glands, lymph nodes, bone marrow, small intestine, lungs, and thymus; hypercholesterolemia and normal to elevated plasma lipids; foam cells in marrow

In Wolman disease, death during infancy if untreated

In CESD, premature atherosclerosis

Treatment: Enzyme replacement with sebelipase alfa, a recombinant human lysosomal acid lipase

Cerebrotendinous xanthomatosis (cholestanol lipidosis; 213700*)

Sterol 27-hydroxylase

Onset: Adolescence

Urine metabolites: Elevated 7-alpha-hydroxylated bile alcohol

Clinical features: Juvenile cataracts, tendon and skin xanthomas, xanthelasma, fractures, atherosclerosis, dementia, spinal cord paresis, cerebellar ataxia, developmental disability, pseudobulbar paralysis, leukodystrophy, peripheral neuropathy

Treatment: Chenodeoxycholic acid, statins

Neuronal ceroid lipofuscinosis

Onset: In infantile form, 6–12 months

In late infantile form, 2–4 years

In juvenile forms (including CLN9), 4–10 years

In adult form, 20–39 years

In variant infantile forms, 4–7 years

In progressive epilepsy form, 5–10 years

Urine metabolites: None

Clinical features: In infantile and late infantile forms, developmental delay, microcephaly, optic and cerebral atrophy, retinal degeneration, blindness, flexion contractures, hypotonia, ataxia, myoclonus, seizures, loss of speech, hyperexcitability, autofluorescence in neurons, granular osmiophilic deposits in cells, increased serum arachidonic acid, decreased linoleic acid

In juvenile and adult forms, features of above forms plus extrapyramidal signs, progressive loss of walking ability, school and behavioral difficulties

Treatment: Supportive care

Infantile form (CLN1, Santavuori-Haltia disease; 256730*)

Palmitoyl-protein thioesterase-1

Late infantile form (CLN2, Jansky-Bielschowsky disease; 204500*)

Lysosomal pepstatin-insensitive peptidase

Juvenile form (CLN3, Batten disease, Vogt-Spielmeyer disease; 204200*)

Lysosomal transmembrane CLN3 protein

Adult form (CLN4, Kufs disease; 204300*)

Palmitoyl-protein thioesterase-1

Variant late infantile form, Finnish type (CLN5; 256731*)

Lysosomal transmembrane CLN5 protein

Variant late infantile form (CLN6; 601780*)

Transmembrane CLN6 protein

Progressive epilepsy with intellectual disability (600143*)

Transmembrane CLN8 protein

CLN9 (609055*)

* For complete gene, molecular, and chromosomal location information, see the Online Mendelian Inheritance in Man® (OMIM®) database.

Table
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Oligosaccharidosis and Related Disorders

Disease (OMIM Number)

Defective Proteins or Enzymes

Comments

Sialidosis (256550*)

Neuraminidase 1 (sialidase)

Type I (cherry-red macular spot-myoclonus syndrome, mild form)

Onset: 8–25 years

Urine metabolites: Increased sialyloligosaccharides

Clinical features: Cherry-red macular spot, insidious vision loss, cataracts, progressive myoclonus and ataxia, normal intelligence, increased deep tendon reflex

Treatment: Supportive care

Type II (congenital, infantile, juvenile, and childhood forms)

Onset: In congenital form, in utero

In infantile form, birth to 12 months

In juvenile and childhood forms, 2–20 years

Urine metabolites: Increased sialyloligosaccharides

Clinical features: All of features of type I plus coarse facies, hypotonia, hepatomegaly, ascites, inguinal hernia, growth delay, muscle wasting, laryngomalacia, dysostosis multiplex

Treatment: Supportive care

Galactosialidosis (Goldberg syndrome, combined neuraminidase and beta-galactosidase deficiency; 256540*)

  • Neonatal form

  • Late infantile form

  • Juvenile/adult form

Protective protein/cathepsin A (PPCA)

Onset: In neonatal form, birth to 3 months

In late infantile form, 1st year

In juvenile/adult form, adolescence but with wide variability

Urine metabolites: Elevated sialyloligosaccharides but no free sialic acid

Clinical features: Coarse facies, corneal clouding, cherry-red macular spot, intellectual disability, seizures, dysostosis multiplex, hearing loss, hemangiomas, valvular heart disease

Treatment: Supportive care

Sialolipidosis (phospholipidosis; mucolipidosis IV, Berman disease; 252650*)

Onset: 1st year

Urine metabolites: No mucopolysaccharides

Clinical features: Severe (Berman disease) and mild forms

Developmental delay, corneal opacities, visual deficiency, strabismus, hypotonia, increased deep tendon reflexes; no radiographic skeletal abnormality, macrocephaly, or organomegaly

Treatment: Supportive care

Mannosidosis

Onset: In type I, 3–12 months

In type II, 1–4 years

Urine metabolites: Mannose-rich oligosaccharides

Clinical features: Coarse facies, macrocephaly, macroglossia, cataracts, gingival hypertrophy, slight hepatosplenomegaly, dysostosis multiplex, hypotonia, hearing loss, bowed femur, pancytopenia, recurrent respiratory infections, immunodeficiency and autoimmunity, developmental disabilities

Treatment: Supportive care, consideration of bone marrow or stem cell transplantation

Alpha-mannosidosis (248500*), type I (severe) or II (mild)

Alpha-D-mannosidase

Beta-mannosidosis (248510*)

Beta-D-mannosidase

Onset: 1–6 years

Urine metabolites: Disaccharides, mannosyl-(1-4)-N-acetylglucosamine, heparan sulfate

Clinical features: Coarse facies, deafness, delayed speech, hyperactivity, genital angiokeratoma, tortuous conjunctival vessels

Treatment: Supportive care, consideration of bone marrow or stem cell transplantation

Fucosidosis (230000*)

  • Type I (severe infantile form)

  • Type II (mild form)

Alpha-L-fucosidase

Onset: In type I, 3–18 months

In type II, 1–2 years

Urine metabolites: Oligosaccharides

Clinical features: Short stature, growth delay, coarse facies, macroglossia, cardiomegaly, recurrent respiratory infections, dysostosis multiplex, hernias, hepatosplenomegaly, angiokeratoma, anhidrosis and elevated sweat chloride, developmental disability, hypotonia changing to hypertonia, cerebral atrophy, seizures, spastic quadriplegia, vacuolated lymphocytes

Most patients from Italy or southwestern US

Treatment: Supportive care, consideration of bone marrow or stem cell transplantation

Aspartylglucosaminuria (208400*)

N-Aspartylglucosaminidase

Onset: 2–6 years

Urine metabolites: Aspartylglucosamine

Clinical features: Growth delay, microcephaly, cataracts, coarse facies, macroglossia, mitral insufficiency, hepatomegaly, diarrhea, hernias, recurrent respiratory infections, macro-orchidism, mild dysostosis multiplex, angiokeratoma corporis diffusum, acne, developmental disabilities, hypotonia, spasticity, cerebral atrophy, seizures, speech delay, hoarse voice

Increased frequency in Finnish populations

Treatment: Supportive care, consideration of bone marrow or stem cell transplantation

Winchester syndrome (277950*)

Metalloproteinase-2

Onset: Early infancy

Urine metabolites: None

Clinical features: Short stature, coarse facies, corneal opacities, gingival hyperplasia, joint contractures, osteoporosis, kyphoscoliosis, vertebral compression, carpotarsal osteolysis, ankylosis of small joints of feet, diffuse thickened skin, hyperpigmentation, hypertrichosis

Treatment: Supportive care

Schindler disease

N-Acetyl-galactosaminidase

Type I (infantile severe form; 609241*)

Onset: 8–15 months

Urine metabolites: Oligosaccharides and O-linked sialopeptides

Clinical features: Cortical blindness, optic atrophy, nystagmus, strabismus, osteopenia, joint contracture, muscular atrophy, developmental delay and regression, myoclonus, seizures, spasticity, hyperreflexia, decorticate posturing, neuraxonal dystrophy

Treatment: Supportive care

Type II (Kanzaki disease, adult-onset form; 609242*)

Onset: Adulthood

Urine metabolites: Oligosaccharides and O-linked sialopeptides

Clinical features: Coarse facies, deafness, conjunctival and retinal vascular tortuosity, angiokeratoma corporis diffusum, telangiectasia, lymphedema, mild intellectual impairment, peripheral axonal neuropathy

Treatment: Supportive care

Type III (intermediate form; 609241*)

Onset: Childhood

Urine metabolites: Oligosaccharides and O-linked sialopeptides

Clinical features: Intermediate between types I and II; variable and ranging from seizures and moderate psychomotor retardation to mild autistic features with speech and language delay

Treatment: Supportive care

Congenital disorders of N-glycosylation (CDG), type I (pre-Golgi glycosylation defects)

Onset: Mostly infancy or childhood

Clinical features (some or most of the following): Growth failure, prominent forehead with large ears, high-arched or cleft palate, strabismus, retinitis pigmentosa, pericardial effusion, cardiomyopathy, hepatomegaly, vomiting, diarrhea, liver fibrosis, primary ovarian failure, renal cysts, nephrosis, proximal tubulopathy, kyphosis, joint contractures, ectopic fat pads, orange-peel skin, muscle weakness, hypotonia, strokelike episodes, seizures, olivopontine hypoplasia, peripheral neuropathy, hypothyroidism, hyperinsulinism, factor XI deficiency, antithrombin III deficiency, thrombocytosis, decreased IgA and IgG, leukocyte adhesion defect (in type IIc), hypoalbuminemia, hypocholesterolemia, increased disialotransferrin and asialotransferrin bands when isoelectric focusing of serum transferrin is done

Treatment: Supportive care

CDG Ia (solely neurologic and neurologic-multivisceral forms; 212065*)

Phosphomannomutase-2

CDG Ib (602579*)

Mannose (Man) phosphate (P) isomerase

CDG Ic (603147*)

Dolichyl-P-Glc:Man(9)GlcNAc(2)-PP-dolichol glucosyltransferase

CDG Id (601110*)

Dolichyl-P-Man:Man(5)GlcNAc(2)-PP-dolichol mannosyltransferase

CDG Ie (608799*)

Dolichyl-P-mannose synthase

CDG If (609180*)

Protein involved in mannose-P-dolichol utilization

CDG Ig (607143*)

Dolichyl-P-mannose:Man-7-GlcNAc-2-PP-dolichyl-alpha-6-mannosyltransferase

CDG Ih (608104*)

Dolichyl-P-glucose:Glc-1-Man-9-GlcNAc-2-PP-dolichyl-alpha-3-glucosyltransferase

CDG Ii (607906*)

Alpha-1,3-mannosyltransferase

CDG Ij (608093*)

UDP-GlcNAc:dolichyl-phosphate N-acetylglucosamine phosphotransferase

CDG Ik (608540*)

Beta-1,4-mannosyltransferase

CDG Il (608776*)

Alpha-1,2-mannosyltransferase

Congenital disorders of N-glycosylation, type II (Golgi defects)

Same as for type I, except isoelectric focusing of serum transferrin shows increased monosialotransferrin, disialotransferrin, trisialotransferrin, and asialotransferrin bands

For type IIb, normal pattern

CDG IIa (212066*)

Mannosyl-alpha-1,6-glycoprotein-beta-1,2-N-acetylglucosminyltransferase

CDG IIb (606056*)

Glucosidase I

CDG IIc (Rambam-Hasharon syndrome; 266265*)

GDP-fucose transporter-1

CDG IId (607091*)

Beta-1,4-galactosyltransferase

CDG IIe (608779*)

Oligomeric Golgi complex-7

* For complete gene, molecular, and chromosomal location information, see the Online Mendelian Inheritance in Man® (OMIM®) database.

Table
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Lysosomal Transport Defects

Disease (OMIM Number)

Defective Proteins or Enzymes

Comments

Sialuria

Infantile sialic acid storage disorder (269920*)

Sodium phosphate cotransporter

Onset: At birth

Urine metabolites: Increased free sialic acid

Clinical features: Growth failure, coarse facial features, dysostosis multiplex, nystagmus, ptosis, gingival hypertrophy, cardiomegaly, heart failure, hepatosplenomegaly, nephrosis, death at about age 1 year

Treatment: Supportive care

Finnish type (Salla disease; 604369*)

Sodium phosphate cotransporter

Onset: 6–9 months

Urine metabolites: Increased free sialic acid

Clinical features: Growth failure, developmental disability, ataxia, hypotonia, hypotonia, spasticity, dyspraxia, dysarthria, seizures, gait problems, athetosis; increased frequency in Finland

Treatment: Supportive care

French type (269921*)

UDP-N-acetylglucosamine-2-epimerase/N-acetylmannosamine kinase

Onset: Infancy to early childhood

Urine metabolites: Increased free sialic acid

Clinical features: Coarse facies with normal growth, developmental delay, sleep apnea, hypoplastic nipples, hepatosplenomegaly, inguinal hernias, generalized hirsutism, seizures

Treatment: Supportive care

Neuronal ceroid lipofuscinosis (CLN3, CLN5, CLN6, CLN8)

See table Other Lipidoses

Cystinosis

Cystinosin (lysosomal cystine transporter)

Infantile nephropathic form (219800*)

Onset: 1st year

Urine metabolites: Renal Fanconi syndrome

Clinical features: Growth failure, frontal bossing, photophobia, peripheral retinopathy with decreased acuity, corneal crystals and erosion, rickets, hepatosplenomegaly, pancreatic insufficiency, renal calculi, renal failure, renal Fanconi syndrome, decreased sweating, myopathy, dysphagia, cerebral atrophy, normal intelligence but neurologic deterioration in long-term survivors

Cystine accumulation throughout reticuloendothelial system, white blood cells, and corneas

Treatment: Replacement therapy for Fanconi syndrome, renal transplant for failure, cysteamine orally or as eyedrops, growth hormone

Late-onset juvenile or adolescent form (219900*)

Onset: 12–15 years

Urine metabolites: Renal Fanconi syndrome

Clinical features: Similar to infantile form but milder

Treatment: Similar to that for infantile form

Adult non-nephropathic form (219750*)

Onset: Early adolescence to adulthood

Urine metabolites: Renal Fanconi syndrome

Clinical features: Similar to infantile form but no renal disorders

Treatment: Cysteamine orally or as eyedrops, growth hormone

* For complete gene, molecular, and chromosomal location information, see the Online Mendelian Inheritance in Man® (OMIM®) database.

Table
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Other Lysosomal Disorders

Disease (OMIM Number)

Defective Proteins or Enzymes

Comments

Pycnodysostosis (265800*)

Cathepsin K

Onset: Early childhood

Urine metabolites: None

Clinical features: Short stature, frontal and occipital prominence, delayed closure of anterior fontanel, micrognathia, narrow palate, delayed eruption and persistence of deciduous teeth, hypodontia, aplasia or hypoplasia of clavicles, osteosclerosis, susceptibility to fracture, scoliosis, spondylolysis, brachydactyly, grooved nails

Treatment: Supportive care, growth hormone possibly helpful

Glutamyl ribose-5-phosphate storage disease (305920*)

ADP-ribose protein hydrolase

Onset: 1st year

Urine metabolites: Proteinuria

Clinical features: Coarse facies, hypotonia, muscle wasting and atrophy, loss of speech and vision, seizures, neurologic deterioration, optic atrophy, nephrosis, hypertension, renal failure, developmental disabilities

Treatment: Supportive care

Glycogen storage disease type 2 (Pompe disease)

* For complete gene, molecular, and chromosomal location information, see the Online Mendelian Inheritance in Man® (OMIM®) database.

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