Alternating Hemiplegia of Childhood, neurological comorbidities, intrafamilial variability: case-reports and literature review.

Abstract BACKGROUND Alternating Hemiplegia of Childhood (AHC) is an uncommon and complex disorder characterized by age of onset before 18 months, recurrent hemiplegia of one or either sides of the body or quadriplegia. Neurological comorbidities observed in two couples of AHC affected children are here reported together with data drawn by literature review. Results of genetic analysis obtained in the probands are also discussed. Developmental delay, epilepsy, tonic or dystonic spells, nystagmus and autonomic manifestations are frequently reported. AHC is mainly caused by mutations in ATP1A3 gene, and to a lesser extent in ATP1A2 gene.CASE PRESENTATION Clinical and genetic findings of a couple of twins and a couple of siblings affected by AHC from two different Italian families were deeply examined. Intrafamilial clinical variability was shown in the present cases. A pathogenic variant rs606231437 in ATP1A3 gene was detected in twins. For the affected siblings of family 2, the genetic results showed that the older brother and the healthy father shared a novel variant of GRIN2A (c.3175T>A) gene, and two missense mutations in SCNIB (rs150721582) and KCNQ2 (rs771211103) genes. In the younger brother was found only the GRIN2A variant.CONCLUSIONS Developmental delay, epileptic seizures and motor dysfunction are features frequently associated to paroxysmal hemiplegic attacks. Hemiplegic episode is only a sign even if the most remarkable of several neurological comorbidities in AHC carriers. The comparison of molecular analysis among the four probands brings out how the genetic framework is not recurrent, but may result from an unexpected greater genetic heterogeneity.