Table 2 Muscle biopsy results of individuals reported with biallelic variants in P4HTM.

From: Biallelic P4HTM variants associated with HIDEA syndrome and mitochondrial respiratory chain complex I deficiency

  

Current patient

Rahikkala et al [5] and Kaasinen et al [8]

  

Family 1: P1

Family 2: P2

Family 3: P5

Family 5: P13

Age (Age deceased)

(7 months)

(5 years)

18 years

(8 years)

(61 years)

Age at muscle biopsy (where specified)

6 months

2.5 years

8.5 years

61 years

Muscle biopsy

Histology

Mild myopathic changes

Significant abnormal variation in fibre size with type 2 predominance and coexpression of fast and slow myosin isoforms. Many fibres expressing neonatal myosin.

Normal histology

Electron microscopy showing increased mitochondria and some with enlarged and abnormal shapes

Increased variability in muscle fibre diameter, hypertrophied muscle fibres, scattered small atrophic fibres, basophilic muscle fibres

(Autopsy specimen)

Unspecific type 2 muscle fibre atrophy and COX-negative fibres

Respiratory chain enzyme testing

Reduced complex I to <30% of control mean

Reduced complex IV to 50% of control mean (marginal)

Normal complexes II and III

Reduced complex II + III activity to 31% of control

Reduced complexes I–III to 41% of control

Reduced complex IV to 38% of control

NR

NR

  1. NR not reported.