#253200
ICD+
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| MUCOPOLYSACCHARIDOSIS TYPE VI | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Alternative titles; symbols | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| MPS VI; MPS6 MAROTEAUX-LAMY SYNDROME ARYLSULFATASE B DEFICIENCY ARSB DEFICIENCY N-ACETYLGALACTOSAMINE-4-SULFATASE DEFICIENCY | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Phenotype Gene Relationships | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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| Phenotypic Series | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Clinical Synopsis | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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| A number sign (#) is used with this entry because mucopolysaccharidosis type VI (MPS VI, MPS6) is caused by mutation in the gene encoding arylsulfatase B (ARSB; 611542). | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Description | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Mucopolysaccharidosis type VI is an autosomal recessive lysosomal storage disorder resulting from a deficiency of arylsulfatase B. Clinical features and severity are variable, but usually include short stature, hepatosplenomegaly, dysostosis multiplex, stiff joints, corneal clouding, cardiac abnormalities, and facial dysmorphism. Intelligence is usually normal (Azevedo et al., 2004). | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Clinical Features | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Maroteaux et al. (1963) first described this disorder as a novel dysostosis associated with increased urinary excretion of chondroitin sulfate. Alder (1939) reported a brother and sister who developed changes in the hip joints at puberty. The sibs also had azurophilic cytoplasmic inclusions in polymorphonuclear leukocytes. The boy developed a waddling gait, and both sibs were found to have bony destruction in the shoulders, hips, and skull, and later in the knees and spine. The sister died of an unknown cause. The boy had herniotomy at the age of 36 years, a decompressive laminectomy C1 to C7 at age 50, hip replacement at age 51, and operation for aortic stenosis at age 60. He was very intelligent and a dedicated violin maker. Gitzelmann et al. (1987) determined that fibroblasts from the brother had only 2 to 3% residual arylsulfatase B deficiency, consistent with MPS VI. The leukocyte inclusions, referred to as 'Alder granules' (Alder, 1939) or 'Reilly granules' (Reilly, 1941), were a striking finding. Levy et al. (1980) showed that platelets as well as leukocytes show Reilly granules in MPS VI. Peterson et al. (1975) reported a pregnant woman with MPS VI who had myelopathy due to compression of the cervical spinal cord by thickened dura. During the last trimester, she had severe neurologic deterioration with spastic quadriparesis and impairment of sphincter function. There was no improvement 2 months after delivery, so a cervical laminectomy and longitudinal splitting of the dura from C-5 to the foramen magnum was done. She experienced good return of function. Young et al. (1980) and Poser et al. (1983) described a mild form of MPS VI in a 41-year-old woman with spastic tetraplegia due to compressive myelopathy secondary to dural thickening. She had normal intelligence, was a college graduate, and mother of 2 children. Wilson et al. (1980) described a 43-year-old man with MPS VI and aortic stenosis who had successful aortic valve replacement. He had short stature (150 cm tall). Two brothers were similarly affected with MPS VI and aortic stenosis. Saul et al. (1984) described a 15-year-old boy with enzymatically confirmed MPS VI and stature at the 75th percentile (174 cm). He had corneal clouding and joint stiffness. Vestermark et al. (1987) reported a case of enzymatically proven Maroteaux-Lamy syndrome in which there was severe mental retardation at age 8 years. Since mental retardation is highly unusual in MPS VI, it may have had another cause in this patient. Cantor et al. (1989) described glaucoma in 4 adult women with MPS VI, 3 of whom were sisters. The authors suggested that the initial mechanism was secondary angle closure due to thickening of the cornea. An alternative mechanism could be obstruction of the trabecular meshwork by mucopolysaccharides, causing secondary open-angle glaucoma. Tonnesen et al. (1991) described a mildly affected Maroteaux-Lamy patient who had normal total excretion of MPS but elevated excretion of dermatan sulfate in the urine. The level of arylsulfatase B was as low as that in severe MPS VI. The patient was a 33-year-old man who presented to an orthopedic surgery department at age 6, and again at age 27, for hip abnormalities. His height was 160 cm. Dysplasia in both hips and slightly increased thoracic kyphosis were found. Cardiologic and ophthalmologic examinations were normal. Litjens et al. (1992) reported an 11-year-old boy with severe MPS VI. He presented at 1 day of age with edema of the hands and feet and respiratory distress. He already had coarse dysmorphic features and skeletal survey showed advanced bone age. Dysostosis multiplex was evident on skeletal survey at 2 days of age. A blood film showed inclusion bodies in myeloid cells and in some monocytes and lymphocytes. Levels of dermatan sulfate in the urine were grossly elevated. He had corneal clouding at 3 months of age, which became so dense as to make him blind by 7 years, when a left corneal transplant was done. Hydrocephalus required shunting at 4 years, and cervical cord compression resulting from upper cervical instability required surgical stabilization at 6 years of age. Genetic analysis identified a homozygous mutation in the ARSB gene (611542.0005). Tan et al. (1992) described a brother and 2 sisters and a fourth unrelated patient with a mild form of MPS VI complicated by stenosis of the aortic and mitral valves. Double-valve replacement was successfully performed in a 30-year-old architect and his 34-year-old school teacher sister and in the unrelated patient, a 21-year-old college freshman. Respiratory problems were indicated by difficult intubation and problems with sleep apnea. Neufeld and Muenzer (1995) classified patients with MPS VI into severe, intermediate, or mild forms. The severe form was characterized by very early onset and severe progression of symptoms: facial dysmorphism, skeletal abnormalities, compression of the spinal cord, corneal clouding, hepatosplenomegaly, and mental retardation. The mild form was characterized by very late onset and absence of mental retardation. The intermediate form showed the middle of the spectrum of phenotypes. Schwartz and Cohen (1998) described the development of hydrocephalus in a patient with Maroteaux-Lamy syndrome who had had bilateral corneal transplantation at the age of 7 years. Azevedo et al. (2004) reported clinical and biochemical studies of 28 MPS VI patients evaluated at a Brazilian center. Age at symptom onset varied from before 6 months (48%), 6 to 30 months (40%), to 36 months or older (12%). Seven families (27%) were consanguineous. The most common clinical features included short stature, coarse facial features, corneal clouding, joint contracture, claw hands, thickened skin, hirsutism, umbilical hernia, and splenomegaly. EKG abnormalities were found in 74%; most had valvular abnormalities. Only 1 child had poor school performance, which was attributed to poor economic conditions. Swiedler et al. (2005) conducted a cross-sectional survey of individuals with MPS VI to establish demographics, urinary glycosaminoglycan (GAG) levels, and clinical progression of the disease. The survey evaluated 121 individuals affected with MPS VI over the age of 4 years from 15 countries, representing more than 10% of the estimated world prevalence of the disease. Impaired physical endurance, as measured by the distance achieved in a 6-minute walk, could be demonstrated across all age groups. High urinary GAG values (greater than 200 microg/mg creatinine) were associated with an accelerated clinical course comprised of age-adjusted short stature and low body weight, impaired endurance, compromised pulmonary function, and reduced joint range of motion. An unexpected result was the predominance of urinary GAG values less than 100 microg/mg creatinine for those participants over the age of 20 years. In the absence of longitudinal data, Swiedler et al. (2005) concluded that urinary GAG levels could predict clinical morbidity and that longer-term survival may be associated with urinary GAG levels below a threshold of 100 microg/mg creatinine. Mut et al. (2005) reported a boy with MPS VI who presented at age 18 years with spastic quadriparesis. MRI showed spinal canal stenosis at multiple levels of the cervical, thoracic, and lumbar regions. Ligamentum flavum hypertrophy caused by excessive deposition of mucopolysaccharides was found to be the principal pathology responsible for the cord compression and myelopathy. Decompression surgery resulted in clinical improvement. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Biochemical Features | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Brooks et al. (1990) described a monoclonal-based system using an immunochemical technique coupled with enzyme kinetic analysis for immunoquantification of the ARSB enzyme, which normally is present at low levels. Studies of cultured skin fibroblasts derived from MPS VI patients suggested a range of mutants, with either no quantifiable protein or protein lacking enzyme activity. Brooks et al. (1991) characterized the residual N-acetylgalactosamine 4-sulfatase in fibroblasts from 16 MPS VI patients. Fibroblasts from the most severely affected patients contained the lowest levels of 4-sulfatase protein, usually with few epitopes detected, whereas fibroblasts from mildly affected patients had higher levels of 4-sulfatase protein, with all 7 epitopes detected. A 44-year-old patient, with no clinical signs of MPS VI and reduced 4-sulfatase activity and protein (both 5% of normal) and dermatansulfaturia, had 5% of normal catalytic capacity. Except for slight photophobia and hearing loss, clinical and radiologic examination failed to reveal any of the signs expected for MPS VI patients (Hopwood, 1991). The other 15 MPS VI patients had 0 to 1.4% of the catalytic capacity of fibroblasts from normal controls. Brooks et al. (1991) proposed that enzyme replacement therapy achieving a correction of more than 5% of normal catalytic capacity would be required to avoid the onset of the MPS VI clinical phenotype. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Inheritance | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Black et al. (1986) reported a large, consanguineous, German Acadian ('Cajun') family from rural Louisiana in which 11 persons, including monozygotic twins, had MPS VI. Inheritance was clearly autosomal recessive. Although distributed in 6 sibships over 2 generations, all had the same surname, derived from an immigrant who came from the same area in Germany as did the consanguineous family reported by Spranger et al. (1970). | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Clinical Management | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Krivit et al. (1984) reported successful bone marrow transplantation in a 13-year-old girl with MPS VI. Full engraftment was present for 24 months. She showed normal arylsulfatase B activity in peripheral lymphocytes and granulocytes, with lesser increases in liver biopsy specimens. Urinary excretion of acid mucopolysaccharide decreased, and ultrastructural evidence of accumulated dermatan sulfate was no longer detectable in bone marrow cells, in peripheral-blood cells, or in Ito cells of liver. Twenty-four months after engraftment, hepatosplenomegaly was substantially decreased and cardiopulmonary function was normal. Visual acuity and joint mobility were also improved. The patient returned to school and continued to perform well in academic studies. Herskhovitz et al. (1999) described the results of bone marrow transplantation (BMT) in 4 patients with MPS VI, 3 of whom underwent BMT due to cardiomyopathy and 1 for severe obstructive sleep apnea. During a follow-up period ranging between 1 and 9 years, the facial features became less coarse in all patients and cardiac manifestations improved or remained stable. However, skeletal changes persisted or progressed, although posture and joint mobility improved, and all patients remained ambulatory. The authors concluded that BMT may prolong survival and improve quality of life in MPS VI patients. Giugliani et al. (2007) provided detailed management guidelines for MPS VI. They reviewed enzyme replacement therapy and bone marrow transplantation. Also included were guidelines for specific management of affected organ systems, such as respiratory, cardiac, skeletal, ophthalmologic, and central nervous system. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Molecular Genetics | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| In a patient with mucopolysaccharidosis type VI, born of consanguineous parents, Wicker et al. (1991) identified a homozygous mutation in the ARSB gene (611542.0001). In patients with MPS VI, Jin et al. (1992) identified homozygous or compound heterozygous mutations in the ARSB gene (611532.0002-611542.0004). In 9 patients with MPS VI, Litjens et al. (1996) identified several mutations in the ARSB gene (see, e.g., 611542.0008-611542.0010). All patients were compound heterozygotes and showed variable phenotypes ranging from mild to severe. For each patient, the combined biochemical phenotypes of the 2 mutant sulfatase alleles demonstrated a good correspondence with the observed clinical phenotype. Litjens and Hopwood (2001) stated that a total of 45 clinically relevant mutations had been identified in the ARSB gene in patients with mucopolysaccharidosis type VI. Missense mutations represented the largest group, with 31 identified. No common mutations had been described, making screening of the general population difficult. Villani et al. (1999) found 5 novel mutations of the ARSB gene in Italian patients with MPS VI. Each defect was confirmed by restriction enzyme or amplification refractory mutation system (ARMS) analysis. Among 12 Spanish and 4 Argentinian patients with MPS VI, Garrido et al. (2007) identified 19 different mutations, including 9 novel mutations, in the ARSB gene. The most common mutant alleles were splice site mutations, 611542.0011 and 611542.0012, which accounted for 21.9% and 12.5% of mutant alleles, respectively. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Population Genetics | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Using multiple ascertainment sources, Nelson et al. (2003) obtained an incidence rate of MPS VI in western Australia for the period 1969 to 1996 of approximately 1 in 320,000 live births. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| History | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Jordans (1947) reported a Dutch family in which 9 individuals in 3 generations had granulation anomalies of the leukocytes, similar to Alder or Reilly granulations. The inclusions were apparently indistinguishable from those observed in mucopolysaccharidoses, but the pattern of inheritance was autosomal dominant. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| See Also: | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Barton and Neufeld (1972); DiFerrante et al. (1974); Goldberg et al. (1970); Haskins et al. (1979); Isbrandt et al. (1996); Maroteaux and Lamy (1965); Paterson et al. (1982); Quigley and Kenyon (1974); Sanguinetti et al. (1986); Stumpf et al. (1973); Van Dyke et al. (1981) | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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