Mucolipidosis III: clinical and laboratory findings

In 1966, Maroteaux and Lamy described 4 girls with a disease akin to the Hurler syndrome, but without excess urinary acid mucopolysaccharides. They called the disorder Hurler pseudopolydystrophy. In 1970, Spranger and Wiedemann coined the term 'genetic mucolipidoses' and designated pseudo Hurler polydystrophy as mucolipidosis (ML) III. During these evaluation of several cases of the pseudo Hurler polydystrophy phenotype, a consistent pattern of clinical and radiographic changes was found to be associated with an unusual pattern of ultrastructural and biochemical changes in cultured fibroblasts. The authors undertook clinical and biochemical investigation of patients presenting with this phenotype. The authors' experience was with 18 patients 10 males and 8 females. Their ages were between 6 and 28 years of age. The families all traced their ancestry to western Europe, with the majority from the British Isles. There were 5 sib pairs in the group - 3 brother sister, one brother brother and one sister sister. There were 23 normal sibs in the 13 families. Other than the sibs, there was no family history of a similar disorder, and no consanguinity was detected. From these experience with these patients, the authors feel it is possible to define the evolution of the phenotype of pseudo Hurler polydystrophy. Typically, the disorder becomes apparent at about 2-4 years of age by stiffness and deformity of the fingers with restriction of mobility in the large joints, particularly the shoulders. Arthritis, especially rheumatoid arthritis, might be considered a diagnostic possibility but evidence of inflammation is lacking. By the age of 6, the facies have begun to coarsen and radiographs suggest a mucopolysaccharidosis but the urine contains normal amounts of acid mucopolysaccharides. By 6 years of age, growth, which had been normal until this point, begins to fall off, such that by teenage life these patients are at or below the third percentile. Between 6 and 8 years of age, mild, fine peripheral corneal clouding may be noted on slit lamp examination but it never becomes grossly apparent. The corneal clouding is sufficiently mild that, unless specifically looked for, it may be overlooked.