TABLE 1.

Clinical, biochemical, and radiological data of case 1–3.

	Case 1	Case 2	Case 3
General information
Age at onset (years)	21	22	17
Age at diagnosis (years)	22	23	17
Family history	−	−	−
Time from diet change to symptoms (months)	12	Several	Several
Time between symptoms and start of B2 (months)	7	11	6
Clinical symptoms
Hearing loss	−	+	+
Vision loss	−	+	−
Bulbar weakness	++	+	+
Muscle weakness	++	+	−
Sensory symptoms	+	−	−
Respiratory symptoms	−	−	−
Neurological examination
Cranial nerves	Nystagmus, bilateral facial weakness, tongue atrophy with fasciculations, hoarse, high pitched voice	Vision 0.3 in both eyes, bilateral facial weakness, facial numbness, fasciculations tongue, hoarse, high pitched voice	Bilateral facial weakness, unilateral ptosis, dysarthria
Motor function	Severe distal, mild proximal weakness in legs. Increased muscle tone in legs. Bilateral atrophy of tibialis anterior	Mild distal weakness in arms, severe distal weakness in legs	No obvious impairment
Reflexes	Brisk in arms, pathologically increased in legs, extensor plantar responses	Normal except for decreased Achilles tendon reflexes	Normal
Coordination	Intact	Intact	Intact
Sensory function	Sensory ataxia	Intact	Intact
Biochemical abnormalities (ref in plasma)
Acylcarnitine profile	N.A.	C8‐carnitine: 0.53 (0.04–0.22) C10:1‐carnitine: 0.25 (0.04–0.22) C10‐carnitine: 0.64 (0.04–0.30) C12‐carnitine: 0.16 (0.04–0.14) C14:1‐carnitine: 0.22 (0.02–0.18)	N.A.
FAD (nmol/l)	N.A.	46.2 (46–114)	N.A.
FMN (nmol/l)	N.A.	1.6 (0.8–21.4)	N.A.
Riboflavin (nmol/l)	N.A.	1.2 (3.9–49)	N.A.
Imaging
MRI brain	Bilateral T2 hyperintensity of corticospinal tracts	Bilateral enhancement of the trigeminal, facial and acoustic nerves	Contrast enhancement of both facial nerves and the right vestibulocochlear nerve
MRI spinal cord	Enhancement of anterior nerve roots of cauda equina	Enhancement of cauda equina nerve roots	Normal
CSF
Leucocytes (ref 1–10E6/L)	1	1	1
Protein (ref 0.24–0.49 g/L)	1.1	0.7	0.5

Abbreviation: N.A., not available.