Acute lymphoblastic leukemia in a child with Leri-Weill syndrome and complete SHOX gene deletion : A Case Report

Background. Leri-Weill syndrome (LWS) ranks among conditions with short stature homeobox gene (SHOX) haploinsufficiency. Data on possible association of SHOX aberrations with malignant diseases are scarce. Methods and Results. We report a unique case of an 8-year-old girl who was successfully treated for acute lymphoblastic leukemia (pre-B ALL, intermediate risk) and was subsequently diagnosed with LWS due to characteristic clinical appearance (short disproportionate stature, Madelung deformity of the wrist) and molecular genetic examination (complete deletion of SHOX). An identical SHOX deletion was identified also in the patient’s mother. Leukemic cells of the patient were retrospectively examined by array comparative genomic hybridization (aCGH), which revealed five regions of deletions at chromosome X, including the SHOX gene locus. Conclusion. Growth retardation in children with hemato-oncologic malignancies cannot always be attributed to cytotoxic treatment and should be carefully evaluated, especially with regards to growth hormone therapy.


INTRODUCTION
Leri-Weill syndrome or Léri-Weill dyschondrosteosis (LWS), first described in 1929 (ref. 1 ), is a rare pseudoautosomal dominant genetic disorder characterized by skeletal dysplasia with disproportionate short stature, mesomelia (i.e.shortening of the middle parts of the limbs) and characteristic Madelung wrist deformity 2 .LWS is caused by mutations of the short stature homeobox (SHOX) gene located within the pseudoautosomal region (PAR1) of both sex chromosomes (Xp22 and Yp11).SHOX haploinsufficiency was reported as causative for short stature in women with Turner syndrome 3 and subsequently its mutations have been identified in patients with LWS and Langer mesomelic dysplasia 4,5 and in approximately 2-16% of cases with idiopathic (nonsyndromic) short stature including children born small for gestational age 3,[6][7][8][9] .SHOX abnormalities have been associated with various physical features such as scoliosis, increased carrying angle of the elbow, deformities of the forearm and tibiae, shortening of the fourth and fifth metacarpals, malformations of the middle ear, exostoses, high-arched palate, micrognathia and muscular hypertrophy 8 .Mutations of other genes located within Xp22.3 cause monogenic X-linked syndromes such as Kallmann syndrome, chondrodysplasia punctata, ichthyosis and learning/behavioral difficulties 10,11 .
Much attention has been paid to SHOX as one of the main growth regulators, however, less is known about its association with other pathological conditions, such as disorders of hematopoiesis and malignant tumors.Here we report a unique case of coincidence of LWS and acute lymphoblastic leukemia (ALL).
Nevertheless, at the regular follow-up examination at the age of 11 years, disproportionate short stature with shortening of the forearms and tibia and muscular hypertrophy were recognized (Fig. 2).The patient's height at the age of 11 years was 127 cm (-2.5 standard deviation (SD), Fig. 3).On wrist X-ray, the skeletal age was accelerated by 1 year and Madelung deformity was detected (Fig. 4).
The patient's history was reviewed: she was delivered at term with a normal birth weight (3000 g) and birth length (52 cm).Her psychomotor development was normal.However, her growth curve since early childhood was following the approximately -2.5 SD percentile of the  national height standards.This had been previously attributed to a familial disposition; the patient's parents also had short stature: mother 149.2 cm (-2.6 SD), maternal grandmother 150 cm and father 160 cm (-2.4 SD, Fig. 3).
Mutations and deletions in the SHOX gene were examined in peripheral blood using polymerase chain reaction (PCR), heteroduplex formation, single nucleotide polymorphism (SNP)-based detection by denaturing high-pressure liquid chromatography (DHPLC) and sequencing (SHOX-DNA-Dx, Esoterix, CA, USA; www.esoterix.com).Complete deletion of the SHOX gene was confirmed.Despite the fact that there was an ongoing clinical trial with growth hormone in 2001, the patient did not receive the treatment due to late diagnosis.She had an early onset of puberty (at 11 years) and at the time of LWS diagnosis her Tanner stages were B2, Ph1, A1.The patient had menarche at the age of 11 years and 10 months and her postmenarchal growth was minimal; her final height was 147.7 cm, i.e. approximately -2.5 SD (Fig. 3).She delivered a boy at the age of 19 years.
The suspicion of LWS was raised in the patient's mother who also displayed disproportionate short stature and Madelung deformity.Using the same molecular genetic test (SHOX-DNA-Dx, Esoterix), the identical complete deletion of the SHOX gene was confirmed.
The patient's parents provided informed consent for publication.

DISCUSSION
The list of indications for growth hormone therapy in children is increasing, with LWS being added in 2007 in the European Union.Thus, an appropriate detection of SHOX aberrations is vital for timely initiation of growth hormone treatment.Reports on SHOX status in malignant diseases are scarce.A connection between SHOX2 methylation of cell-free circulating DNA and lung cancer has been suggested; however SHOX2, unlike SHOX, is an autosomal homeobox gene located on chromosome 3 (ref. 12,13).Translocations of the TFE3 transcription factor gene at Xp11 in tumor cells are related to papillary renal cell carcinoma 14 .Regarding disorders of hematopoiesis, a predisposing locus for Hodgkin lymphoma was placed in proximity to SHOX in PAR1.This was based on familiar coinheritance of LWS and Hodgkin lymphoma and a predominance of same-sex sibling pairs among those affected with Hodgkin disease 15 .Recurrent somatic mutations in P2RY8 gene located in PAR1 have been identified in cases of diffuse large B-cell lymphoma 16 .In an elderly male with concurrent LWS, Klinefelter syndrome and hepatocellular carcinoma followed by myelodysplastic syndrome, breakpoint regions did not involve cancer genes and thus the causality between dic(X;Y)(p22.33;p11.32)and mentioned malignancies was considered unlikely 17 .
PAR1 includes genes with an important role in immune response and hematopoiesis, such as granulocyte macrophage colony-stimulating factor receptor (CSF2RA or GM-CSFR), interleukin 3 receptor alpha (IL3RA)   and cytokine receptor-like factor 2 (CRLF2) whose rearragements resulting from deletions in PAR1 have been detected in leukemic cells in a substantial percentage (14%) of children with ALL and reported to be associated with mutation of JAK kinases, IKZF1 alterations and poor treatment outcomes 18 .Adverse prognostic impact of CRLF2 rearrangements leading to CRLF2 overexpression in children and adults with ALL has since then been confirmed by numerous studies 19,20 .The CRLF2 gene in leukemic cells of our patient taken at the time of ALL diagnosis was undeleted, as well as P2RY8, CSF2RA and IL3RA.False negativity of FISH for SHOX deletion was caused by the fact that the probe only partially covered the SHOX gene and fluorescence was emitted from the residual part of the probe.Monoallelic SHOX deletion was confirmed by aCGH and thus the phenotype of the leukemic blasts was in this case in accordance with genotype.
Among 1184 gene loci within the deleted regions, genes involved in DNA repair, hematopoiesis and growth regulation were identified in our patient (Table 1), most importantly ARL11, BRCA2, FOXO4 and GATA1 which are associated with leukemia [21][22][23] .
The clinical significance of 13q deletion involving the retinoblastoma gene (RB1), a known tumor supressor gene whose numerous mutations are associated with retinoblastoma, several subtypes of sarcoma, melanoma and other types of cancer, is unknown in our patient.The role of loss or inactivation of RB1 in leukemogenesis has been documented 24 .
Regarding muscular hypertrophy in our patient, we also considered that the involvement of the dystrophin gene (DMD, Xp21.2-p21.1)within the deleted Xp region may be the causal aberration.However, the DMD deletion was found only in leukemic cells and information on germinal DMD status is missing.Furthermore, muscular hypertrophy, particularly involving calf muscles, affects up to 80% of the LWS patients 8,25 , which is much more frequent than in molecular dystrophy carriers.No other confirmed cases or signs of muscular dystrophy have been observed in the patient or her family members.Therefore, we assume that in this case the association of calf hypertrophy with DMD gene is unlikely.
Unfortunately, the patient was later lost to follow-up, and therefore the remission sample was unavailable for aCGH examination.An absence of somatic DNA for further analyses, such as aCGH and next generation sequencing, is a significant drawback of our study.
The case presented here of concurrent LWS and ALL is the first published to date.A previously reported case of a child with thrombocytopenia and absent radii (TAR syndrome) who developed ALL (ref. 26) is relevant; although genetically distinct, TAR syndrome similarly manifests with radial growth abnormalities and short stature.It is therefore necessary to distinguish between growth retardation as a side effect of ALL treatment, which is infrequent 27 , and possibly other unrelated pathological conditions.We emphasize the importance of careful evaluation of auxology and somatic morphology for timely diagnosis of SHOX haploinsufficiency in children with unexplained short stature.Precise detection of SHOX abnormalities is important not only for therapeutic intervention but also for the estimation of prognosis, genetic counseling and search for other affected family members.

CONCLUSION
This is a unique report of a child diagnosed with inherited Leri-Weill syndrome (LWS) with characteristic clinical features and complete deletion of the SHOX gene in the first remission of acute lymphoblastic leukemia (ALL) at the age of 11 years.We highlight the importance of auxology and somatic morphology assessment in children with malignant disease.Growth retardation can be caused not only by chemo-or radiotherapy but also by other diseases or rare underlying syndromes in which timely treatment with growth hormone is indicated.

Fig. 2 .
Fig. 2. Short disproportionate stature in a patient with Leri-Weill syndrome and ALL.The patient had an adult height of 147.7 cm (picture taken at the age of 15 years).Note shortening of forearms and tibia and muscular hypertrophy.

Fig. 4 .
Fig. 4. Madelung deformity of the wrist.The deformity is congenital, bilateral and is characterized by growth disturbance in the volar-ulnar distal radial physis.This results in a bowing and shortening of radius and dorsal dislocation of distal ulna (A).(B) Triangulation of distal radial epiphysis with shortening of the ulnar segment (A/B index>4.0).(C) Volar translation of the hand and wrist causes restriction of movement.

Table 1 .
Selected genes and biological processes affected by gene deletions in leukemic cells of the patient with LWS and ALL.