Introduction: Leri-Weill dyschondrosteosis (LWD) is caused by haploinsufficiency of the SHOX gene, located in the pseudoautosomal region (PAR 1) of the short arm of the X and Y chromosomes. The gene is expressed in highest levels in bone tissue and its product likely controls the chondrocyte apoptosis. Deletions and duplications are most frequent, point mutations are responsible for minority of the cases. The main clinical symptoms of LWD include disproportionate short stature, mesomelic shortening of the limbs, Madelung deformity of the forearm and limited wrist movement. Patients with LWD seem to benefit from growth hormone treatment.
Case description: A 16 years old boy attended the clinic because of short stature. He was born after 3rd uncomplicated pregnancy and delivery, full term, weight 2950 g, lenght 49 cm. Neonatal period was normal. His first steps and first tooth eruption were at 1 year of age, his first words at 2 years of age. He had frequent respiratory infections. There was no familly history of inherited diseases and cosanguinity. On examination: W 69 kg, H 150.5 cm, SDS −2.97. Disproportionate short stature was noted with mesomelic shortening of the limbs and Madelung deformity of the forearms. Other findings were micrognathia, thoracic scoliosis, high-arched palate, unilateral cryptorchidism and relatively small testes volume (12 ml at Tanner V). Investigations (biochemistry, thyroid function, gonadotropins, testosterone, IGF1) were normal. Radiographic changes typical for Madelung deformity were found, the bone age was adequate. US confirmed left-sided inguinal cryptorchidism. MRI of pituitary region was normal. Karyotype was 45,X/46,X,del(Y)(q11.22).
Discussion: We present a patient with typical LWD phenotype but with karyotype corresponding to mixed gonadal dysgenesis. Probably SHOX deletion even in small percentage of cellular lines is sufficient to cause the typical features of LWD. Also, the cytogenetic result shows the distribution of the cellular lines in the lymphocytes but in other tissues (bones) the percentage of 45,X line could be greater. Microdeletion in Yp11.2 is also possible but its detection is beyond the potential of the conventional cytogenetic testing. A point mutation is another possibility and a targeted genetic testing is required. Though our patient is well virilized he has unilateral inguinal cryptorchidism and smaller testes which is suspicious of some form of gonadal dysgenesis. He will undergo orchidopexy and testicular biopsy. Because of the limited remaining growth potential treatment with growth hormone will not be of benefit.
27 Sep 2018 - 29 Sep 2018