Mucopolysaccharidosis VI is a lisosomal storage disorder caused by deficiency of arylsulfatase B (ASB), inherited as an autosomal recessive trait. We investigated 3 such cases: the first was diagnosed in a 6-year old girl and the other two, a girl and boy siblings, were 2.9 and 4.1y, respectively. The children were normal at birth and the onset of clinical manifestations began at the age of 2y, associated with growth deficiency without mental deterioration. They were screened for inborn errors of metabolism and increased urinary levels of glycosaminoglycans were detected. A clonidine stimulation (0.1mg/m²) for hGH gave peak levels of 6.2, 5.6 and 4.6ng/ml, in cases 1, 2 and 3. In response to insulin-induced hypoglycemia (0.1UI/kg), hGH peak values were 30.3, 8.8 and 8.2ng/ml, respectively. IGF1 and IGFBP3 in cases 2 and 3 were normal. In all, TSH, free T4, anti-TPO, anti-TG antibodies, Ca, and P were normal. On follow-up, secondary adrenocortical insufficiency was detected and treated in case 2. Delayed bone age and elongated sella turcica were found. Pituitary MRI scans showed an empty sella in cases 2 and 3. Like other dysmorphic dwarfisms, we were unable to find hormonal deficiencies that could justify the short stature.
Mucopolysaccharidosis VI; Dysmorfic dwarfism; Arylsulfatase B; Endocrine growth evaluation
