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Hajdu-Cheney syndrome is a very rare (about 50 cases reported) of connective tissue, one of several other osteolytic disorders: other types of acroosteolysis may be of neurological, metabolic, vascular or dermatological etiology. When isolated, they can be genetic, but also due to infection or tumors. The dominant form of acro-ostolysis is characterized by short stature, progressively disappearing distal phalanges and crowded carpal bones. Failure of ossification of cranial sutures can be seen, with thickened cranial vault, absent frontal sinus, elongated sella turcica, and progressive basilar impression. Hair is thick and straight, eyebrows and eyelashes prominent. Ears are low-set with prominent lobes. The nose is broad with anteverted nostrils. A resorption of alveolar process often induces an early loss of teeth, the vertebrae are biconcave, and osteopenia can lead to collapse and scoliosis is frequent. Several additional manifestations have been described in isolated cases: cystic kidneys, congenital heart disease, hydrocephalus, cleft palate, hepatosplenomegaly. While most patients have a normal intellectual quotient, some have mild mental retardation. Diagnosis is rarely made in childhood and pain is a frequent first manifestation, especially in the hands. The patients are weak, and traumatic fractures often occur. Osseous compression may result in decreased stature, and the basilar compression may be life-threatening. Biochemistry and osteodensitometry reveal excessive bone resorption, with early osteoporosis that might be treated by biphosphonates. Autosomal dominant inheritance is typical, but the genetic defect and molecular pathogenesis of the syndrome are unknown. Sporadic cases are presumably due to fresh mutations. |