aInstitute of Biomedical Engineering, National Taiwan University, Taipei
bDepartment of Orthopedics, China Medical University Hospital, Taichung, Taiwan, ROC
Correspondence to Tung-Wu Lu, DPhil, Institute of Biomedical Engineering, National Taiwan University, No. 1, Sec. 1, Jen-Ai Road, Taipei 100, Taiwan, ROC Tel/fax: +886 2 33653335; e-mail: firstname.lastname@example.org
Potocki–Lupski syndrome results from the duplication of chromosome 17 band p11.2. This is the first report of a case of Potocki–Lupski syndrome with teratologic dislocation of both hips. The diagnosis was made by chromosomal analysis. The association between Potocki–Lupski syndrome and musculoskeletal disorders may help elucidate the etiology and prognosis of the syndrome.
Potocki–Lupski syndrome (PTLS) is a newly diagnosed syndrome associated with a microduplication of chromosome 17 band p11.2 1–3. The clinical features of PTLS typically include infantile hypotonia, poor feeding, failure to thrive, developmental delay, and intellectual disability; older children often show speech and language impairment, inattention, autistic spectrum disorder, and behavioral abnormalities, with some having cardiovascular anomalies 2–5. The phenotypic spectrum in adults with PTLS has not been determined.
Only one previous report has reported on the musculoskeletal presentation associated with PTLS, describing thoracic kyphosis, postural scoliosis, marked ligamentous laxity of the joints, flat feet, and long toe 6. The present report is the first one to describe teratologic dislocation of both hips in PTLS.
A male patient was diagnosed with 17p11.2 duplication syndrome (PTLS) by fluorescence in-situ hybridization examination (Fig. 1) at the age of 7 months after the observation of developmental delay and teratologic dislocation of both hips (Fig. 2).
The infant was born by cesarean section owing to breech malposition, with a birth weight of 2430 g and a gestational age of 36 weeks. At birth, the Apgar score was 8 and 9. He was the first child of a 24-year-old, healthy mother (gravida I, para I). There was no family history of developmental dysplasia of the hip and no other genetic or congenital disorder of the patient.
The patient was found to have developmental delay, cornea nebula of both eyes, white pupil with rolling eyes, scissor leg, increased deep tendon reflexes of all four limbs, and poor fetal movement. Highly arched palate, micrognathia, epicanthal fold, and mild malformation of the right ear were also documented. Foramen ovale patency was also noted by echocardiography. No structural abnormality was found on brain ultrasound. Bilateral teratologic dislocation of hips with lumbar hyperlordosis and negative skin fold were also noted.
Closed reduction for the bilateral teratologic dislocation of hips was attempted but was unsuccessful. Therefore, open reduction with iliopsoas tenotomy and rectus femoris tendon lengthening of both hips was performed, at the age of 9 months for the right hip and 11 months for the left hip. Hip spica was applied after the operation for adjustment of alignment. A 15-month postoperative radiograph showed reduction of both hips (Fig. 3). The infant’s growth status was almost normal.
This is the first report of the presentation of teratologic dislocation of both hips in PTLS. Our patient was diagnosed with PTLS by chromosomal study, which showed 17p11.2 duplication. As reported with other cases, our patient presented with poor feeding, failure to thrive, developmental delay, and intellectual disability. However, our patient also had hypertonia, unlike previously reported cases of PTLS. Symptoms included scissor leg, hypertonic posture, bilateral limb spasticity, clonus, and increased deep tendon reflexes of all four limbs. We believe that these findings point to a new, previously unrecognized subtype of PTLS.
Various factors have been found to be associated with teratologic dislocation of the hip, including genetic anomaly, joint laxity, intrauterine malposition, and race. The present case indicates that duplication of 17p11.2 may be an additional factor leading to teratologic dislocation of the hip. The possibility of the duplication in this case may be larger than typical PTLS cases.
As described by other researchers, PTLS may mimic a connective tissue disorder 6. This may be because of the human microfibril-associated glycoprotein gene MFAP4 6,7. The dysfunction of this gene is a possible factor in connective tissue disorder, including joint laxity, which may ultimately lead to teratologic dislocation of the hip. Thus, PTLS may present with teratologic dislocation of the hip. Further study and a review of more cases are required to help elucidate the etiology and prognosis of this syndrome.
The authors acknowledge the Paediatric Department in China Medical University Hospital for supplying the photocopy of the chromosomal study using FISH examination.
Conflicts of interest
There are no conflicts of interest.
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