Hematopoietic Stem Cell Transplantation in Mucopolysaccharidosis VI: A Case Report and 4-year Follow-Up

Dafne Horovitz ¹ Anneliese Barth ¹ Juliana Folloni Fernandes ² Roberto Giugliani ³

¹Reference Center for Rare Diseases / National Institute of Women, Children and Adolescents Health Fernandes Figueira - Fiocruz, Brazil
²Itaci - Instituto Da Criança - Hospital Das Clínicas Da Faculdade De Medicina Da Universidade De São Paulo; Hospital Israelita Albert Einstein, Brazil
³Department of Genetics, Federal University of Rio Grande do Sul, Brazil

Mucopolysaccharidosis VI (MPSVI) is a multisystemic and progressive disease. Enzyme replacement therapy (ERT) has been shown to improve health, lifespan, quality of life and growth. Despite its benefits, ERT is a lifelong treatment with a significant burden on patients and families. Herein, we present the case of a 5-year-old girl with an inguinal hernia and ovarian extrusion at 45 days, and recurrent airway infections from 6 months who was referred for genetic evaluation after being admitted to hospital for pneumonia and atelectasis. MPSVI was diagnosed at 11 months. At baseline, she presented with a head circumference on the upper limit, hepatosplenomegaly, mild corneal opacity, and lumbar gibbus with vertebral beaking. A ventriculoperitoneal shunt was placed at 15 months and ERT was initiated at 13 months. After a long deliberation regarding the risks versus the benefits of lifelong therapy, the parents opted for hematopoietic stem cell transplantation (HSCT). She was transplanted unsuccessfully with donor umbilical cord blood at 19 and 21 months and finally transplanted for a third time with the father´s bone marrow at 23 months (the father was chosen as a donor as his enzyme activity was higher than the mother’s). ERT continued to be administered throughout the process until engraftment was confirmed and Arilsulphatase B activity in the leucocytes was satisfactory (112 nmol/hr/ml, normal range 116−287) at 26 months.

She has currently minimal aortic and mitral thickening and underwent orthopaedic procedures for genu valgum, trigger fingers and carpal tunnel syndrome. Corneal opacity is no longer observed on ophthalmological evaluation and her height is slightly below the 3rd centile. Engraftment and enzyme activity remain satisfactory. She is healthy, had no further hospital admissions or complications and the family is very satisfied with their quality of life without the need for weekly ERT infusions. Longer follow-up and similar case reports could help in considering HSCT as a treatment option for very young children diagnosed with MPSVI.