Serpentine Fibula-Polycystic Kidney Syndrome

At a glance

Rare skeletal dysplasia with elongated serpentine fibulas, bowed lower legs and forearms, bowed radii, polycystic kidneys, small stature, unusual facial appearance, large skull and occipital depression, severe pectus excavatum, hirsutism, and deafness but normal intelligence.

Synonym

SFPKS.

Incidence

Very rare. Limited number of patients have been reported.

Genetic inheritance

Autosomal recessive; predominance of affected females.

Pathophysiology

Mutation in NOTCH2 gene on 1p12. Now considered one end spectrum of Hajdu Cheney Syndrome.

Diagnosis

Clinical and radiological features. Most striking radiological feature is the elongated and deformed S-shaped fibulae. Other features include bowing of forearms and lower legs and metatarsus adductus. Abdominal ultrasonography must be used to confirm the presence of polycystic kidney. Chromosomal study is normal.

Clinical aspects

Unusual facial appearance: coarse hair, hirsute forehead and neck, marked eyebrows, micrognathia. Skull: large skull with occipital depression in one patient. Thorax: shield chest; pectus excavatum. Urology: polycystic kidney. Other features include short neck, low-set ears, and deafness in some cases. Cardiac: atrial septal defect and patent ductus arteriosus in one report. Growth: small stature in most cases. Intelligence is normal in all cases. Renal function usually well maintained until late.

Precautions before anesthesia

The cardiac function must be assessed through examination, chest radiography, ECG, and echocardiogram to rule out cardiac defect. Assess the airway for potential difficulty if micrognathia and short neck are present. Biochemistry screen must be obtained for potassium, creatinine, and urea (to assess renal function).

Anesthetic considerations

Potential for difficult airway with abnormal facies.

Pharmacological implications

Considerations for cardiac defect include prophylactic antibiotic, avoidance of air embolism, and adequate rehydration.

Other conditions to be considered

• ☞Melnick-Needles Syndrome: Characterized by severe typical facies (exophthalmos [frog-like eyes], full red cheeks, high forehead, micrognathia, and malalignment of teeth), flaring of the metaphyses of long bones, S-like curvature of bones of legs, irregular constrictions in the ribs, and sclerosis of base of skull. It is caused by mutations in the gene encoding filamin A.

• ☞Hajdu Cheney Syndrome: Characterized by acroosteolysis, multiple wormian bones, and hypoplasia of ramus of mandible. The presence of generalized osteoporosis and multiple fractures of the skull, spine and digits, short stature, persistent cranial sutures, early loss of teeth, and joint laxity are reported as features associated in varying degrees. The patients show bathrocephaly (projection of the occipital area and a deep groove at the lambdoidal sutures between the occipital and parietal bones). In addition to micrognathia and narrow high palate, prominent ears may be a feature.

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