Estimating the relative frequency of leukodystrophies and recommendations for carrier screening in the era of next‐generation sequencing

Leukodystrophies are a heterogeneous group of heritable disorders characterized by abnormal brain white matter signal on magnetic resonance imaging (MRI) and primary involvement of the cellular components of myelin. Previous estimates suggest the incidence of leukodystrophies as a whole to be 1 in 7,000 individuals, however the frequency of specific diagnoses relative to others has not been described. Next generation sequencing approaches offer the opportunity to redefine our understanding of the relative frequency of different leukodystrophies. We assessed the relative frequency of all 30 leukodystrophies (associated with 55 genes) in more than 49,000 exomes. We identified a relatively high frequency of disorders previously thought of as very rare, including Aicardi Goutières Syndrome, TUBB4A‐related leukodystrophy, Peroxisomal biogenesis disorders, POLR3‐related Leukodystrophy, Vanishing White Matter, and Pelizaeus‐Merzbacher Disease. Despite the relative frequency of these conditions, carrier‐screening laboratories regularly test only 20 of the 55 leukodystrophy‐related genes, and do not test at all, or test only one or a few, genes for some of the higher frequency disorders. Relative frequency of leukodystrophies previously considered very rare suggests these disorders may benefit from expanded carrier screening.     

The Prevalence of Type A Personality in the Children of Alcoholics

Three studies are reported which investigate the prevalency of an excess risk of type A personality in the children of alcoholics (COAs). Reports in the clinical literature suggest there is an excess risk of type A in COAs, but this has never been empirically demonstrated. The Matthews Youth Test for Health (MYTH) was administered to nonalcoholic mothers of 46 COAs and 65 matched controls to measure children's type A competitiveness and impatience-aggression. Results were significant only for greater impatience-aggression in COAs. In a second study, 104 COAs and controls matched for age, sex, race, and father's occupational status were rated by military fathers of intact families using MYTH. The results of the first study were not replicated for COAs, and there was no correlation between a father's Jenkins Activity Scale (JAS) score and his child's type A personality. A third study of 70 matched COAs and controls used the Hunter-Wolf A-B Rating scale, a self-rating scale for children and found no significant differences in children's type A personalities based on membership in an alcoholic family, sex, or birth order. It was concluded that the discrepancy between clinical reports and the present data may have been due to misperceptions about successful, hardworking COAs who, particularly in contrast to their more notorious siblings, may be viewed as "workaholics" and improperly labeled as type A personalities.     

Antifluoridationists Persist: the Constitutional Basis for Fluoridation

The controversy surrounding fluoridation persists. In recent years opponents of fluoridation have resorted to the courts with increasing frequency and have achieved a few victories in the trial courts. To date, however, no appellate court has ruled against fluoridation. This article discusses the constitutional basis for the court decisions upholding fluoridation and the main arguments put forth by the antifluoridationists. Five of the more recent cases are summarized, as is the first fluoridation case to be appealed to the US Supreme Court. The article concludes that the legal validity of fluoridation in the United States has been thoroughly tested in the courts and confirmed. It appears that the antifluoridationists will concentrate their future legal attacks on the "harmful effects" of fluoridation on health and the environment. If they can convince the courts that even a few people were truly harmed, the delicate balance between the rights of the state to fluoridate in order to protect the public's health and the rights of the individual not to be harmed could well shift. In closing, the question is raised whether the US Congress has the power to pass legislation either to mandate or forbid fluoridation.