Progressive weakness of skeletal muscle is the hallmark of muscular dystrophies. It is often accompanied by cardiomyopathy and respiratory insufficiency. It has generally been perceived as incurable diseases, while the advent of genetic therapy is changing the paradigm. Most research and achievements have been for the treatment of Duchenne muscular dystrophy, while it is promising to hope for therapies for other myopathies. Drugs for nonsense read-through and exon skipping are already approved for clinical use in Europe and the United States, respectively. Gene therapy using adeno-associated virus is in early phase of clinical trial. In this review, most promising genetic therapies will be briefly described.
In this report, the phenotypes of three patients from two families with mucopolysaccharidosis type II (MPS II) are compared: a novel variant and recombinant variant of IDS gene. The results of urine in patients showed a pronounced increase in glycosaminoglycan excretion with decreased iduronate-2-sulfatase enzyme activity in leukocyte, leading to a diagnosis of MPS II. A patient has a novel variant with 1 bp small insertion, c.1224_1225insC in exon 9, which caused frameshifts with a premature stop codon, and two patients have a recombination variant, c.418+495¬¬_1006+1304del, leading to the loss of exons 4, 5, 6, and 7 in genomic DNA, which is relatively common in Korean patients. They had different phenotypes even in the same mutation. The patients have now been enzyme replacement therapy with a significant decrease in glycosaminoglycan excretion. Further study on residual enzyme activity, as well as experience with more cases, may shed light on the relationship between phenotypes in MPS II and gene mutations.
A 10-year and 5 month-old girl with developmental delay, intellectual disability, attention deficit hyperactivity disorder, poor weight gain, and microcephaly was transferred to our pediatric clinic for genetic evaluation. Her height was within the 5–10th percentile, and her weight was under the 3rd percentile. On the social maturity scale, her developmental status was scored as 3 years 9 months for social age, and the social quotient was 35.98. A chromosomal microarray analysis was performed and the microduplication at chromosome 16p was observed: arr[GRCh37] 16p11.2 (29580020_30190029)×3. Currently, the patient is diagnosed with Grade 2 intellectual disability and is attending a computerized cognitive rehabilitation class twice weekly. In addition, nutritional support and growth follow up are also ensured in the Pediatric Gastrointestinal and Endocrinology clinic.