ESPE Abstracts

Background: Hypotonia-Cystinuria Syndrome (HCS) is a rare autosomal recessive disease characterized by generalized hypotonia, nephrolithiasis, short stature, minor facial dysmorphism, hyperphagia, and rapid weight gain in late childhood. Microdeletion can be detected in part of the SLC3A1 and PREPL genes in these cases. Growth hormone deficiency is rarely seen in these patients and adequate growth can be achieved with growth hormone therapy.

Case: An 8-year-old male patient, who was followed up by the pediatrics nephrology and pediatric metabolism departments due to cystunuria and nephrolithiasis, presented with short stature. On physical examination, his height 113.5 cm (<3p, -2.61 SD), weight 44.1 kg (38p, -0.30 SD), body mass index 21.7 kg/m2 (+2.14 SD) were measured. He had mild mental retardation, bilateral downslanted palpebral fissures, blepharophimosis, bilateral large ears, small square hand, and bilateral short 5th metacarpal. Bone age was determined to be 8 years. The growth velocity rate was insufficient in the annual follow-ups. The pituitary gland height was measured as 3.05 mm and there was an insufficient response to growth hormone stimulation tests. Growth hormone therapy was started and genetic analysis was planned for HSS. In the new sequence sequencing analysis, homozygous deletion was detected between exons 2 and 14 of the PREPL gene at the chromosome 2p21 locus. With 6 months of growth hormone treatment at a dose of 0.2 mg/kg/week, he increased in height by 6.3 cm (12.6 cm/year).

Conclusion: We shared our experience of using growth hormone therapy for 6 months in our patient, whom we thought to have hypotonia-cystinuria syndrome and confirmed by genetic diagnosis. Growth hormone deficiency is rarely seen in HCS. It should be considered in the differential diagnosis of syndromic short stature with disease-specific phenotypic features of HCS.