Edition of 19 December 2017

The authors described an autosomal-recessive syndrome, with failure to thrive, severe global developmental delay, microcephaly, axial hypotonia, pyramidal signs, dystonic postures, seizures, irritability, and self-mutilation. Aside from low blood carnitine levels, biochemical and metabolic screen was normal, with growth hormone deficiency in one patient. Electromyography was normal, with no specific findings in brain MRI/MRS. Muscle biopsy showed the unaffected overall organization of muscle fibres, yet positive foetal alpha myosin staining, suggesting regeneration. Homozygosity mapping with whole-exome sequencing identified a single disease-associated mutation in PAX7, segregating in the kindred.

The authors identified two hemizygous missense mutations in ATP6AP2 responsible for a glycosylation disorder with liver disease, immunodeficiency, cutis laxa, and psychomotor impairment in two families. Partial chromatograms showed X-linked segregation for all patients.