Prevailing Ex-Pfizer Scientist Has Genetically Determined Illness

I don't get it. How does an employee with, by all appearances, an inherited illness prevail in litigation against a company for personal injury? At least the federal judge in the case of McClain v Pfizer threw out the issue of whether a Pfizer-bioengineered virus caused the plaintiff's recurrent paralytic illness.

Nevertheless, a jury awarded nearly $1.4 million to ex-Pfizer scientist Becky McClain, by ruling that the company had violated free-speech and whistle-blower laws. (The judge left the personal-injury issue to workers' compensation litigation.)

Coverage of the jury's decision is provided by the NYT, which also reveals that McClain, 52, suffers from "a potassium deficiency that causes sporadic and temporary paralysis"—in other words, hypokalemic periodic paralysis, a rare, genetically determined* disorder of ion channels in muscle (ie, a channelopathy). Unfortunately news coverage of the trial fails to stress the crucial genetic feature of McClain's reported illness. (They also fail to note that her OSHA complaint was evidently dismissed.)

Approximately 60% of cases of Hypo PP are due to a mutation in CACNA1S (calcium channel) gene; 20% are caused by a mutation in the SCN4A (sodium channel) gene. The remainder are probably due to new dominant mutations, according to information cited in a review by Venance et al. These ion-channel mutations cause the aberrant depolarization of muscle fibers, which renders them inexcitable; the clinical result is periodic paralysis. It's not clear what kind of Hypo PP-related mutation, if known, is harbored by McClain.

The essential features of Hypo PP, beyond its genetically determined nature, are listed:

• Age at onset: 1st or 2nd decade
• Duration of paralytic attacks: hours to days (may be diffuse or focal)
• Usual triggers: rest after exercise, carb loading
• Ictal potassium level: low
• Cardiac arrhythmias or skeletal developmental abnormalities: no (unlike Anderson-Tawil syndrome**)
• Response to potassium: improvement of weakness

Hypo PP is diagnosed on the basis of episodic paralysis, low serum potassium levels during the paralysis, and EMG features (post-exercise features may be particularly helpful). For anybody presenting with Hypo PP-consistent symptoms after the age of 20 years or whose family history is nonexistent, thyroid function should be assessed to exclude thyrotoxic PP.

According to news reports, McClain—who has an MS degree—claims that her paralytic illness was triggered by infection with a genetically engineered lentivirus at Pfizer's Groton, CT, campus. The Connecticut Law Tribune reports that McClain left work in early 2004 after developing her alleged symptoms.

Though her doctor cleared her to resume working a few months later, her attorney instead negotiated with Pfizer over her work conditions. Unable to reach an agreement, McClain was terminated in May 2005; Pfizer said it was because she had abandoned her job.

By then, McClain had filed a complaint with OSHA. It was dismissed when investigators ruled that her complaints were without merit; the OSHA report cited Pfizer for making "substantial efforts" to address McClain's concerns.

Probably smelling the high possibility of litigation from McClain on whatever grounds, it seems reasonable to conclude that Pfizer would have bent over backwards to accommodate McClain and her safety concerns—at least on some kind of sensible level.

According to the Center for Public Awareness in Bioethics web site, McClain has a bachelor's degree from Indiana University and a Master of Science in Public Health from the University of Texas School of Public Health in Houston. She worked for Pfizer as an unspecified scientist from 1996 to 2005 and filed her suit against the company in 2006.

EMG = electromyography; OSHA = Occupational Safety and Health Administration.

* Prevalence is reported at 1 in 100,000. The disorder is inherited in autosomal dominant fashion, with reduced penetrance in women. Also sporadic mutations are reportedly common in Hypo PP.

** The triad of PP, ventricular ectopy, and skeletal anomalies.