The alpha-actinins are a multigene family of four actin-binding proteins related to dystrophin. The two skeletal muscle isoforms of alpha-actinin (ACTN2 and ACTN3) are major structural components of the Z-line involved in anchoring the actin-containing thin filaments. In humans, ACTN2 is expressed in all muscle fibres, while ACTN3 expression is restricted to a subset of type 2 fibres. We have recently demonstrated that alpha-actinin-3 is absent in approximately 18% of individuals in a range of human populations, and that homozygosity for a premature stop codon (577X) accounts for most cases of true alpha-actinin-3 deficiency. Absence of alpha-actinin-3 is not associated with an obvious disease phenotype, raising the possibility that ACTN3 is functionally redundant in humans, and that alpha-actinin-2 is able to compensate for alpha-actinin-3 deficiency. We now present data concerning the expression of ACTN3 in other species. Genotyping of non-human primates indicates that the 577X null mutation has likely arisen in humans. The mouse genome contains four orthologues which all map to evolutionarily conserved syntenic regions for the four human genes. Murine Actn2 and Actn3 are differentially expressed, spatially and temporally, during embryonic development and, in contrast to humans, alpha-actinin-2 expression does not completely overlap alpha-actinin-3 in postnatal skeletal muscle, suggesting independent function. Furthermore, sequence comparison of human, mouse and chicken alpha-actinin genes demonstrates that ACTN3 has been conserved over a long period of evolutionary time, implying a constraint on evolutionary rate imposed by continued function of the gene. These observations provide a real framework in which to test theoretical models of genetic redundancy as they apply to human populations. In addition we highlight the need for caution in making conclusions about gene function from the phenotypic consequences of loss-of-function mutations in animal knockout models.

Appropriate management of posterior plagiocephaly requires differentiation of occipitoparietal flattening caused by lambdoid synostosis from that caused by deformational forces. In a 2 1/2-year prospective study of 115 infants presenting with unilateral posterior cranial flattening, only one child had synostotic posterior plagiocephaly (lambdoid synostosis), whereas 114 infants had deformational posterior plagiocephaly. Deformational occipitoparietal flattening was more common on the right (61 percent) than on the left (30 percent), and minor contralateral frontal flattening was not unusual (52 percent). The ipsilateral ear was anteriorly displaced in virtually all infants (97 percent). Some infants had ipsilateral torticollis (19 percent); a few had contralateral torticollis (8 percent). Gender ratio was 3:1, male:female. A total of 114 infants with deformational posterior plagiocephaly were treated conservatively either by head positioning in the crib (n = 63) or with a molding helmet (n = 51). Outcome was assessed by pretreatment and posttreatment anthropometry on 53 of these infants, who were either positioned (n = 17) or helmeted (n = 36). Improvement occurred in 52 of 53 patients (mean follow-up 4.6 months), i.e., the difference in length between the long and short transcranial axis diminished in 52 infants (mean 1.2 to 0.7 cm), did not progress in any child, and was unchanged in one infant. At an average age of 10 months, posterior cranial symmetry was better in infants treated with a helmet (mean difference 0.6 cm) than in those managed by positioning (mean difference 1.0 cm) (p < 0.001). Age at initiation of helmet therapy (from 2 to 9 months) was unrelated to rate of improvement. In a 10-year retrospective study, the authors identified 12 infants who had an operation for posterior plagiocephaly. All but one had confirmed premature lambdoid fusion; thus, this condition accounted for 3.4 percent of all primary operations performed for craniosynostosis during this decade (n = 323). In retrospect, the physical findings of synostotic posterior plagiocephaly were not clearly different from those of deformational posterior plagiocephaly. Plain radiography was sometimes used to confirm the clinical diagnosis. Neither sutural narrowing, deep interdigitations, nor perisutural sclerosis indicated lambdoid synostosis. Computed tomography (CT) was necessary if the physical findings were suspicious for lambdoid synostosis or if plain films did not give a definitive diagnosis. Axial CT scans (n = 7) showed a symmetric forehead in all but one patient with lambdoid synostosis. CT studies also demonstrated that auricular position was indeterminate in synostotic posterior plagiocephaly, being anterior, posterior, or symmetric, whereas the ipsilateral ear was virtually always anterior in deformational posterior plagiocephaly.

Seroma formation following abdominoplasty is the most common complication. Concomitant liposuction of the flanks and abdomen with the addition of aggressive undermining leads to higher seroma rates. This association is likely multifactorial and may be secondary to increased resorptive demands placed on the abdominal lymphatics in the setting of greater dead space and larger fluid shifts as a result of liposuction. To reduce seroma rates, surgeons should avoid aggressive liposuction and undermining, particularly in high-risk patients.