Little is known about familial risk factors for mitochondrial DNA deletion disorders. Now data from 226 families have been collected from centres in seven countries (

). Each family had at least one member with chronic progressive external ophthalmoplegia, Kearns Sayre syndrome, or Pearson’s syndrome. For unaffected mothers age did not affect the risk of having a child with a mitochondrial DNA deletion disorder. None of 251 siblings of index cases was affected but the risk for the children of affected mothers was about one in 24.

Virologists at the National Institute of Virology in Pune, India (

; see also comment, ibid: 821–2) have shown that a little known virus, the Chandipura virus, was responsible for an outbreak of acute encephalitis in Andhra Pradesh in 2003 that killed 183 of 329 affected children. After ruling out Japanese encephalitis, West Nile, dengue, measles, coronavirus, paramyxovirus, enterovirus, and influenza viruses, they identified Chandipura virus by electron microscopy, complement fixation, and neutralisation tests on a virus isolated from six patients. The viral RNA was 97% identical with the Chandipura virus reference strain on sequencing and 28 of 55 cases investigated had evidence of recent infection with the virus. The virus was also identified in postmortem brain tissue from one child. …