Aetiological findings and associated factors in children with severe mental retardation

Abstract

The purpose of this study, through a retrospective epidemiological survey carried out over three geographical areas in France, was to characterize the aetiological factors involved in severe mental retardation (SMR) within a geographically defined population of children with disabilities aged between 7 and 16 years. The inclusion criteria for SMR (IQ<50) were met by 1150 children born between 1976 and 1985. Of these children, aetiology was known in 25%, suspected (or unclear) in 26%, and unknown in 49%. These rates of known and suspected aetiology varied between the groups of children with CP and those without CP. An analysis of factors associated with SMR was undertaken among the 144 subjects with SMR, of suspected or unknown aetiology, who had been referred to a neonatal care unit with or without intensive care (NCU) during their neonatal period. These subjects with SMR were compared with 864 children without SMR (control children) who were also referred to an NCU during their neonatal period. The main specific associated factors were a prolonged intubation of more than 24 hours, a very low birthweight (<1500 g) for children with an associated clinical feature of CP, and the presence of isolated neonatal fits and a time of transfer to the NCU of more than 4 hours after birth for children without an associated clinical feature of CP. Although common associated factors were encountered in the children with SMR with CP and the children with SMR without CP, the results of this study suggest differences in the underlying pathogenic factors.

Discontinuity in the genetic and environmental causes of the intellectual disability spectrum

“…Maternal infections during pregnancy (e.g., rubella) have been associated with severe ID in the offspring ( 20 ), as well as exposure to environmental toxins (e.g., lead) during pregnancy or after birth ( 21 – 23 ). Another group of potential environmental risks comprises conditions in pregnancy and birth (e.g., diabetes, preterm birth, and growth restriction) ( 24 ). These have multiple potential etiologies, and their causal role in severe ID requires further research.…”

Clinical application of exome sequencing in undiagnosed genetic conditions

“…The real power of diagnostic sequencing will depend on establishing very large databases that include mutations of interest and corresponding phenotypes. For example, intellectual disabilities and/or congenital abnormalities occur in approximately 3–4% of children,48 49 and a majority of these are due to underlying genetic causes, yet close to 50% of children with one or both of these phenotypes remain undiagnosed 50 51. It is likely that a high proportion of these undiagnosed cases will start to be sequenced annually in the next few years, creating the opportunity for very large databases that will permit the identification of currently unrecognised genotype-phenotype connections.…”

Postural care for people with intellectual disabilities and severely impaired motor function: A scoping review

“…Conversely, only a minority (e.g. <25%; Cans et al., ) of those with intellectual disabilities requiring postural care will have cerebral palsy. Indeed, a number of specific conditions related to intellectual disabilities may result in the need for postural care (Ager et al., ; Burns, Powell, Hsia, & Reinker, ; Butler et al., ; Damasceno, Cristante, Marcon, & Barros Filho, ; Detweiler, Thacker, Hopkins, Conway, & Gripp, ; Imagama et al., ; Karmaniolou, Krishnan, Galtrey, Cleland, & Vijayaraghavan, ; Kerr, Webb, Prescott, & Milne, ; Laurier et al., ; Li, Shen, Liang, & Sheng, ; de Lind van Wijngaarden, de Klerk, Festen, & Hokken‐ Koelega, ; Takebayashi et al., ).…”