Androgen insensitivity syndrome

OBJECTIVE

We provide a review of the literature about the Androgen Insensitivity Syndrome (AIS), its onset and associated developmental anomalies and the genetic alterations causing it.

MATERIALS AND METHODS

We searched PubMed with a larger emphasis on the physiology, genetics and current management of AIS.

RESULTS

AIS is an X-linked recessive Disorder of Sex Development (DSD). It is caused by mutations of the Androgen Receptor, and their large amount and heterogeneity (missense and nonsense mutations, splicing variants, deletions, and insertions) are responsible for the wide spectrum of possible phenotypes of patients, divided into Partial AIS (PAIS) and Complete AIS (CAIS). Once the clinical and laboratory investigations have laid the foundation for a diagnostic hypothesis, it is important to identify the actual karyotype of the individual and search for the mutation in the Androgen Receptor to diagnose with certainty the syndrome. Alternatively, in the absence of such evidence, the diagnosis should more properly be an AIS-like condition, which we describe as well in our report.

CONCLUSIONS

The management of this DSD is based on pharmacotherapies, surgery and psychological support: all of them must be directed to facilitate the patient's life, considering his/her sexual identity.

Amiodarone-induced experimental acute neuropathy in rats

Amiodarone was injected endoneurially at increasing doses into the exposed tibial nerve of rats to study its electrophysiologic and pathologic effects on peripheral nerve fibers. Forty-five male Wistar rats were used, and each of the following concentrations was injected into 15 nerves: 25 micrograms/mL, 50 micrograms/mL, and 100 micrograms/mL. Microinjection of a 25 micrograms/mL concentration of amiodarone resulted in a subacute, incomplete conduction block evident at day 3 postinjection. This conduction block remained stable until day 10 and recovery was complete at day 35. Microinjection of a 50 micrograms/mL concentration of amiodarone produced a faster evolving conduction block, and significant axon degeneration (approximately 40% of fibers). Injection of a 100 micrograms/mL concentration resulted in severe acute motor axon degeneration followed by complete but delayed regeneration. Results of morphological studies closely correlated with electrophysiological findings. Amiodarone thus seems to have a direct toxic effect on axons at high concentrations in the peripheral nerve, and we suggest that different pathological changes described in human amiodarone neuropathy could be related to different concentrations of the drug in the nerve, perhaps due to variability of blood-nerve barrier efficacy.

Pyridoxine neuropathy. A four-year electrophysiological and clinical follow-up of a severe case

In a 54-year-old male a severe sensory neuropathy was observed during treatment for pulmonary tuberculosis with isoniazid (400 mg/day) and pyridoxine (600 mg/day). Eight months after withdrawal from isoniazid the sensory symptomatology was still progressing, although muscle strength was never reduced. A sural nerve biopsy revealed marked loss of large myelinated fibres. Only when pyridoxine treatment was interrupted did a slow improvement begin. A clinical and electrophysiologic follow-up showed a very slow and still incomplete recovery after four years. The possibility of an unusual individual susceptibility to toxic effects of pyridoxine is considered.

[Apropos of a case of myopathy with histologic and electrophysiologic findings of both a myogenic and neurogenic nature]

The authors describe the case of a 36 years old woman suffering from muscular weakness with proximo-distal distribution to legs, and proximal to arms. The disease, appeared during the third decade of life, is slowly becoming more serious. Hematochemical analyses are all within a normal standard; EMG and histopathologic findings prove the existence of both a protopathic and neurogenic trouble in studied muscles. A therapy based on prednisone (50 mg/die) and ACTH (1 mg each 5 days) for a fourty days period doesn't cause essential changes in symptomatology. A cousin (on her mother's side) of our patient suffers from probable "sporadic distal myopathy". The authors discuss if the disease, shown by this patient, may be considered as an atypical form of SDM or if, what appears more probable, it must be nosographically framed as "scapuloperoneal atrophy".