Endocrine Abstracts

Introduction

Mucopolysaccharidosis type 4A (Morquio 4A) is an autosomal recessive lysosomal storage disease caused by a mutation in the gene encoding galactosamine 6 sulphatase (GALNS). It’s main clinical features include short stature, skeletal dysplasia, cloudy cornea, hearing loss and dental anomalies. Herein, a case of Morquio 4A, a rare cause of short stature is presented.

Case report

A 41 year old female patient was admitted to our clinic for short stature. On physical examination height 95 cm, body weight 24 kg, kyphoscoliosis, short neck, pectus carinatum, genu valgum, nasal root flattened, coarse forehead and abnormal gait were detected. There was hearing loss and decrease in vision. There was no previous history fractures. Her parents were relatives and had normal height. Four of her ten siblings were short, two of whom died in the fifth decade. Laboratory tests were normal. DEXA with Z score for L1–L4 and femoral neck were -3.1, -1.7, respectively; BMD was 0.590 g/cm² and 0.600 g/cm² for L1–L4 and femoral neck respectively. Diffuse loss of height in the vertebrae (platyspondyle), sharpening of the anterior vertebrae, shortening of the long bones, enlargement of the metaphysis, diffuse decrease in bone density, irregularity in the epiphyses (epiphyseal displasia) were observed in bone survey examination. These findings were thouht to be compatible with mucopolysaccharidosis type 4A (Morquio 4A). N-acetylgalactosamine 6 sulfatase enzyme activity in leukocyte was<0.1 nmol/mg 17 h (>68). In the genetic analyses, homozygous mutation encoding the C.1157+2T>6(p?) nucleotid was detected in the GALNS (NM-001323544.1) gene. The patient was diagnosed with Morquio 4A (MIM#253000). Vitamin D and calcium were initiated for bone health. Enzyme therapy was planned.

Conclusion

Although Morquio 4A is a rare cause of short stature, it should recognise especially in those with a family history. Carriers of this disease should be determined by advising genetic counseling to the families of these patients. These patients may have many vital organs involvement other than bone, follow up and treatment with a multidisciplinary approach is required. Although there is an enzyme replacement therapy there is no curative therapy yet.