young adults with the autosomal recessive form of the disease Rare forms of phosphorylase b kinase deficiency have been described, in which deposition of glycogen is limited to the heart.26 Glycogen Storage Disease Type VII (Tarui Disease, Muscle Phosphofructokinase I Deficiency) Tarui disease is a rare form of glycogen storage disease that presents in early childhood or adult life with fatigability, muscular weakness, which can be progressive, muscle cramps, and myoglobinuria Typically the heart is spared However, an infantile form of the disease has been described in the members of one family Cardiomyopathy occurred in addition to the progressive muscular weakness, and abnormal deposition of glycogen was noted in the cardiac muscle at autopsy.27 Progressive cardiomyopathy has also been reported in an adult.28 Mucopolysaccharidoses The mucopolysaccharidoses result from deficiency of lysosomal enzymes involved in the degradation of mucopolysaccharides The incompletely degraded mucopolysaccharides then accumulate in the tissues The substances accumulated are dermatan sulfate, heparan sulfate, or keratan sulfate They can accumulate alone or in combination There is skeletal involvement in all forms In most, there is glaucoma and corneal clouding Retinal pigmentation frequently occurs Deafness is a feature of all types In most, there is hepatosplenomegaly Involvement of the central nervous system is common, usually with cervical myelopathy as a consequence of pachymeningitis or atlanto-occipital subluxation Cardiovascular involvement is a feature of all types The mucopolysaccharides are deposited in arterial walls, including the coronary arteries, producing lesions similar to atherosclerosis.29 A dilated aortic root is also frequently seen.30 Deposition in cardiac valves leads to valvar stenosis and/or regurgitation The various forms of these diseases are brought about by deficiencies of 10 identifiable lysosomal enzymes Specific deficiencies can be demonstrated in cultured fibroblasts, and prenatal diagnosis from culture of amniocytes is possible The availability of such diagnosis is important, since there is genetic variability within different forms of mucopolysaccharidoses Mucopolysaccharidosis Type I (α-L-Iduronidase Deficiency) The three major clinical forms of α-L-iduronidase deficiency are Hurler syndrome, Scheie syndrome, and a syndrome intermediate between the two, Hurler-Scheie syndrome These diseases are due to defects in the gene encoding α-L-iduronidase, and multiple defects have been elucidated These include nonsense, missense, insertional, deletional, and splice-type gene defects It was previously thought that the clinical severity of the disease was related to the level of de novo enzyme activity, but no biochemical differences have been identified to distinguish the subtypes.31–33 Hurler Syndrome The defect in Hurler syndrome results in a virtual absence of lysosomal α-Liduronidase This enzyme is responsible for the breakdown of heparan sulfate and dermatan sulfate to heparan and hyaluronic acid, respectively The enzyme is completely absent in fibroblasts but some activity is present in the liver Consequently traces of the breakdown products of heparan and dermatan may be found in the urine As a consequence of this enzyme deficiency, both heparan and dermatan sulfates accumulate in the lysosomes of many tissues When in neurons, the lesions bear some resemblance to those found in Tay-Sachs disease Deposition in the arterial walls is associated with proliferation of smooth muscle cells, and the lesions are described as “pseudoatheromatous.” There is proliferation of both elastic fibers and collagen accompanying the lysosomal accumulation of mucopolysaccharides The babies seem to be normal at birth, the clinical features appearing after the age of 1 year, when the facial features become coarse Premature closure of the skull sutures and hydrocephalus as a consequence of pachymeningitis lead to cranial deformities The characteristic lumbar lordosis develops because of stiff joints Growth retardation then becomes evident after the age of 2 or 3 years; deafness, corneal clouding, and (sometimes) glaucoma subsequently develop The liver and spleen are always enlarged Although the heart is rarely spared, clinical evidence of cardiac involvement is seen only in half the patients Angina pectoris is an occasional symptom because of coronary artery involvement, but more frequently attention is drawn by the finding of a cardiac murmur or systemic hypertension The murmurs are variable and usually not loud Rarely, the murmur of aortic or mitral insufficiency may be heard Cardiac failure as the presenting feature associated with endocardial fibroelastosis has been reported.34,35 There are typical skeletal radiologic features The clavicles have wide medial ends The lower thoracic and upper lumbar vertebrae have a flared and hookshaped appearance There are also changes in the skull and long bones, the latter being more severely affected in the upper limbs The heart is usually enlarged but with no specific silhouette, although left atrial enlargement will occur with severe mitral regurgitation Similarly, there are no specific electrocardiographic features, although combined ventricular hypertrophy is frequent A long QT interval has been reported in some patients.36 Pathologic findings in the heart include deposition of mucopolysaccharide in structures such as the sinus and atrioventricular nodes as well as in the myocardium and endocardium The coronary arteries often demonstrate severe luminal narrowing, and care must be taken whenever these patients are subjected to general anesthesia or sedation, as hypotension can lead to coronary ischemia and death The mitral valve is most frequently involved, followed by the aortic and tricuspid valves Pulmonary valve involvement is only rarely reported Valvar changes include nodular thickening along the free edges, which may lead to stenosis or regurgitation Evidence suggests that the accumulation of dermatan sulfate leads to impaired elastogenesis, which may lead to some of the characteristic arterial and valvar deformities.37 Thickening of the valve leaflets is characteristically seen echocardiographically Left ventricular cavity enlargement will reflect the volume load resulting from valvar regurgitation, and left ventricular mass may be increased as a result of compensatory hypertrophy and deposition of mucopolysaccharide in the myocardium Cardiac catheterization and angiocardiography add little to the diagnostic findings, which include systemic and mild pulmonary hypertension If angiography is performed, the hemodynamics will reflect the severity of valvar insufficiency The disease progresses inexorably, death occurring by the age of 10 years from heart failure, sudden death, or from chest infection Hematopoietic stem cell transplantation has been beneficial in selected patients for many aspects of the disease.38 However, the valvar lesions remain progressive Enzyme replacement therapy with human recombinant α-L-iduronidase has also proved beneficial, but, as with stem cell transplantation, the valvar lesions appear to remain and even