Table 1.

Clinical signs and instrumental data.

	lle215Thr													Gly241Val
Family	Family 1						Family 2	Family 3			Family 4	Family 5	Family 6	Family 7
Patients	Patient IV.2	Patient V.1	Patient IV.9	Patient V.6	Patient IV.4	Patient V.3	Patient II.1	Patient II.2	Patient I.1	Patient II.1	Patient II.1	Patient II.1	Patient II.1	Patient II.1	Patient I2
Age at last examination (years)	59	28	63	26	67	32		35	65	32	48	28	32	36	80
Onset	Subclinical	Asymptomatic	50 years		Childhood	32 years	35 years	Childhood	Asymptomatic	Asymptomatic	45 years	Childhood	Adolescence	early adulthood	adulthood
Clinical myotonia	Mild eye-lid myotonia	Percussion myotonia	Very mild grip myotonia	Very mild grip myotonia	Paramyotonia in the orbicularis oculi and grip myotonia	No myotonia	Fluctuating grip and percussion myotonia	Percussion myotonia	Lid-lag	Mild grip myotonia	Tongue	No	No	lid-lag, grip myotonia, spontaneous and percussion myotonia of the lower limbs
Triggers for myotonia	Absent	Absent	Cold temperature	Cold temperature	Exercise	Pregnancy	Cold temperature	Cold temperature			Cold temperature	Fasting, exercise, rest, stress		cold temperature
Paradoxical myotonia	Absent	Absent	Absent	Absent	Yes	No					No	Yes
Stiffness	Absent	Absent	In the morning	In the morning	Yes	No	Yes	Severe			After exsercise at hands	Yes		lower limbs	mild
EMG	Myotonic discharges	Myotonic discharges	Myotonic discharges	Myotonic discharges	Myotonic discharges	No	Myotonic discharges	Myotonic discharges	Myotonic discharges	na	Myotonic discharges	Myotonic discharges	Myotonic discharges	myotonic discharges	na
Warm-up					No	No					No	No
Muscle pain			Yes	Yes	Yes	No	Yes	Yes			Yes	Yes	No	yes, lower limbs
Muscle weakness					No	No	no				Progressive and diffuse weakness	No
Contractures			Muscle cramps	Muscle cramps	No	No					No		Contractures + muscle cramps
Hypertrophy	Yes	Diffuse			No	No		Diffuse			no		Hypertrophy of calves	mild
CK level (U/L)	300–500	223	na	200	300	Normal	Normal	na	Normal	Normal	na	Normal	Normal	normal	normal
Drugs					Mexiletine	No	No	Mexiletine and clonazepam				Phenytoin, quinine, mexiletine	No	mexiletine, acetazolamide, carbamazepine, phenytoin
Response to drugs					Good response to mexiletine—Worsening of myotonia after statin therapy			Improvement in the frequency, duration and severity of the episodes of stiffness				Phenytoin: not effective quinine: effective, but not tolerated mexiletine: good response		All drugs were not effective
Biopsy	Mild myopathic abnormalities				Increased fiber size variation, type I fibers atrophy, internal nuclei			Mild myopathic abnormalities - type 2B deficiency				Normal. Increased acid fosfatase activity.	Normal
Other diseases			Mild ptosis ogival cleft		Diabetes, hypercholesterolemia and hypertrigliceridia	Mutation of gene of MTHFR		Hypothyroidism			Low serum vitamin D

In grey, the family that does not share the p.Ile215Thr.