Linkage analysis of 15 Utah kindreds demonstrated that a gene responsible for von Recklinghausen neurofibromatosis (NF) is located near the centromere on chromosome 17. The families also gave no evidence for heterogeneity, indicating that a significant proportion of NF cases are due to mutations at a single locus. Further genetic analysis can now refine this localization and may lead to the eventual identification and cloning of the defective gene responsible for this disorder.

Toxoplasma gondii is a highly ubiquitous and prevalent parasite. Despite the cat being the only definitive host, it is found in almost all geographical areas and warm blooded animals. Three routes of transmission are recognised: ingestion of oocysts shed by the cat, carnivory and congenital transmission. In natural populations, it is difficult to establish the relative importance of these routes. This paper reviews recent work in our laboratory which suggests that congenital transmission may be much more important than previously thought. Using PCR detection of the parasite, studies in sheep show that congenital transmission may occur in as many as 66% of pregnancies. Furthermore, in families of sheep on the same farm, exposed to the same sources of oocysts, significant divergent prevalences of Toxoplasma infection and abortion are found between different families. The data suggest that breeding from infected ewes increases the risk of subsequent abortion and infection in lambs. Congenital transmission rates in a natural population of mice were found to be 75%. Interestingly, congenital transmission rates in humans were measured at 19.8%. The results presented in these studies differ from those of other published studies and suggest that vertical transmission may be much more important than previously thought.

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A new method for measuring cranial cavity volume and its application to the assessment of cerebral atrophy at autopsy Cranial cavity volume has been measured at autopsy by occupying the cranial cavity completely with a lubricated balloon filled with water while the calvarium was held in place by a rigid metal coronet. The pressure in the balloon was raised to 150 mm Hg and the water‐filled balloon removed and weighed. Brain volume has been measured by an accurate displacement method. Repeat measurements showed a difference of no more than 8 ml and usually less than 5 ml. The ratio between the brain volume and the cranial cavity volume has been found to be constant in young adults 20–55 years old (92.2±SEM 1.6%). Cerebral atrophy has been measured by observing the deviation from this relationship. We have found a striking decrease in brain volume in normal old people. This is not due to water loss as brain density change with age was found to be slight.