Mortality and cause of death in mucopolysaccharidosis type II-a historical review based on data from the Hunter Outcome Survey (HOS).

Mucopolysaccharidosis type II (MPS II or Hunter syndrome) is a progressive, multisystemic disease caused by a deficiency of iduronate-2-sulfatase. Patients with the severe form of the disease have cognitive impairment and typically die in the second decade of life. Patients with the less severe form do not experience significant cognitive involvement and may survive until the fifth or sixth decade of life. We studied the relationship of both severity of MPS II and the time period in which patients died with age at death in 129 patients for whom data were entered retrospectively into HOS (Hunter Outcome Survey), the only large-scale, multinational observational study of patients with MPS II. Median age at death was significantly lower in patients with cognitive involvement compared with those without cognitive involvement (11.7 versus 14.1 years; p = 0.024). These data indicate that cognitive involvement is indicative of more severe disease and lower life expectancy in patients with MPS II. Median age at death was significantly lower in patients who died in or before 1985 compared with those who died after 1985 (11.3 versus 14.1 years; p alpha 0.001). The difference in age at death between patients dying in or before, relative to after, the selected cut-off date of 1985 may reflect improvements in patient identification, care and management over the past two decades. Data from patients who died after 1985 could serve as a control in analyses of the effects of enzyme replacement therapy with idursulfase on mortality in patients with MPS II.

Mental retardation in a girl with a subtelomeric deletion on chromosome 20q and complete deletion of the myelin transcription factor 1 gene (MYT1).

A great number of syndromes and inborn errors of metabolism associated with impaired development have been observed, but the aetiology of mental retardation remains unclear in a considerable proportion of cases. Here, we present the clinical and molecular data from a patient with a new de novo subtelomeric deletion on chromosome 20 [46,XX.ish del(20)(qter-)]. For further refinement, bacterial artificial chromosome clones are used. The deletion spans exactly two genes called MYT1 and PCMTD2. Both genes play an important role in myelination and regulating neural differentiation. Loss of these two genes seems to be responsible for the severe mental retardation and mild facial dysmorphic features in our young patient. It might show the phenotypic picture of this specified deletion.

Copper concentration of liver tissue under long-term copper-histidine therapy in a patient with Menkes disease.

Copper-histidine is the treatment of choice in Menkes disease but bears the potential risk of copper overload and induced liver cirrhosis. We report normal copper concentrations of liver tissue over an 8-year treatment period with copper-histidine.

The gene copy ratios of SMN1/SMN2 in Japanese carriers with type I spinal muscular atrophy.

Spinal muscular atrophy is an autosomal recessive neurodegenerative disorder with progressive weakness and atrophy of voluntary muscles. The survival motor neuron gene (SMN) is present in two highly homologous copies (SMN1 and SMN2) on chromosome 5q13. Homozygous deletion of exons 7 and 8 of SMN1 is responsible for spinal muscular atrophy. In spinal muscular atrophy patients, SMN2 partially compensates for the lack of SMN1. Previously, we reported the relatively high incidence of a large deletion including the SMN1 region in Japanese spinal muscular atrophy type I patients. In order to further establish the genetic background of Japanese spinal muscular atrophy type I patients, we investigated the SMN1/SMN2 ratio in the carriers. In normal individuals, there is one copy of each gene on the chromosome (the SMN1/SMN2 ratio was 1). Among 15 carriers (14 parents and one carrier sibling of Japanese type I spinal muscular atrophy patients with homozygous deletion of exons 7 and 8 of SMN1), we found that the SMN1/SMN2 ratio was 0.5 or 1 in 11 (73.3%) carriers. The remaining four carriers had an SMN1/SMN2 ratio of 1/3. This finding supports the idea that deletion rather than conversion is the main genetic event in type I spinal muscular atrophy. In addition, the ratio of SMN1/SMN2 among Japanese carriers, which was thought to be higher than that of the Western population, was compatible with the results obtained in Western populations. For further insight into the characteristic genetic background of spinal muscular atrophy in Japanese, determination of the gene copy number is essential.