Joint laxity in the parents of children with temporary brittle bone disease

One controversial cause of unexplained fractures in young children is temporary brittle bone disease. Contributory factors for this disorder include the following: premature birth, twin pregnancy and diminished foetal movement. Heritable factors may also be important. Infants with findings consistent with temporary brittle bone disease were identified from clinical and medico-legal referrals. The routine evaluation of each family included examination of both parents where available for joint laxity using the nine-point Beighton scale. Of 81 children in whom both parents had been examined personally, 40 had at least one parent with a Beighton score of four or more, conventionally regarded as indicative of the hypermobility syndrome. We found no significant difference in laxity when we compared the whole group of mothers with the controls (P = 0.081). The fathers were significantly different from their control group (P = 0.013). When we compared the figures for the most flexible parent of each child, there were significant differences from control subjects both in the mothers and in the fathers (P = 0.042 and P = 0.0065, respectively). We draw attention to the likely autosomal dominant inheritance of this risk factor for temporary brittle bone disease as well as the potential value of assessing parental joint laxity in evaluating children with fractures.