Table 1:

Genotypes and phenotypes of SELENON patients investigated in the present study

	#	Sample ID	Sample type	Origin	Age of biopsy	#SELENON variants	Phenotypic characteristics	†HGMD access N°
Patient	1	UK 3358	Muscle biopsy	U.K.	2 years	c.[713dupA];[802C>T] p.[(N238fs)];[(R268C)]	Normal early motor milestones, rigidity of the spine and rapidly progressive scoliosis from the age of 5 years, requiring scoliosis surgery aged 11. Respiratory insufficiency from the age of 10 years, requiring nocturnal respiratory BiPap	CI022931 CM114823
	2	UK 3866	Muscle biopsy	U.K.	6 years	c.[1282-2A>C];[ 1282-2A>C] p.[?];[?]	Motor delay with sitting at 9 months and walking holding at 1.5 years of age. Recurrent chest infections in the first few years and heart failure due to sleep hypoventilating at age 16 (he was initiated on cuirass jacket ventilation for 2 years then changed to BIPAP). Scoliosis first noticed at age 10 and surgery performed at age 15. Currently walking but limited distance.	CS114832
	3	UK 7220	Muscle biopsy	U.K.	6 years	c.[1A>G];[ 883G>A] p.[(M1V)];[(E295K)]	Progressive muscle weakness. Lumbar lordosis and Rigidity of spine. Recurrent respiratory infections since the age of 9 months. Noctural BiPAP from age 5.	CM022835 CM114829
	4	UK 5314	Muscle biopsy	U.K.	13 years	c.[1384T>G];[1384T>G] p.[(U462G)]; [(U462G)]	Diagnosed at 14 months with axial hypotonia and forward flexed posture on sitting. Through childhood developed spinal rigidity with scoliosis. At the age of 12 referred due to symptoms of severe nocturnal hypoventilation, managed with nocturnal BIPAP. Underwent spinal fusion aged 17 years for progressive scoliosis.	CM022839
	5	UK 7264	Muscle biopsy	U.K.	2 years	c.[1282-2A>C];[ 1282-2A>C] p.[?];[?] (intron 9)	First concern aged 9 months with axial and proximal muscle weakness, and dropped head. Early scoliosis initially noticed aged 2, and frequent falls since acquisition of deambulation at 19 months	CS114832
	6	UK 6508	Muscle biopsy	U.K.	12 years	c.[1315C>T];[1315C>T] p.[(R439*)];[(R439*)]	Delayed motor milestones, right from the first 2 years of life with inability to jump, hop or run, but maintained ability to walk on level ground and going upstairs. Axial proximal facial weakness, contractures and some distal laxity present at age 15. Nocturnal ventilation since the age of 13 years. Obese phenotype.	CM050744
	7	NL 00682	Muscle biopsy	Netherlands	4 years	c.[713dupA];[ 1332_1334del] p.[(N238fs)];[(N444del)]	Delayed motor development, hypotonia and weakness, respiratory weakness for which non-invasive nocturnal ventilation since 10 years of age, permanent wheelchair use since at age 27. Scoliosis operation at age 10	CI022931 Not reported
	8	NL 05244	Muscle biopsy	Netherlands	2 years	c.[943G>A];[ 943G>A] p.[(G315S)];[G315S)]	Delayed motor development, hypotonia and weakness, respiratory weakness for which non-invasive nocturnal ventilation since 16 years of age, intermittent wheelchair use since age 19. Scoliosis operation	CM022836
	9	NL 22413	Muscle biopsy	Netherlands	13 years	c.[943G>A];[ 1332_1334del] p.[(G315S)];[N444del]	Delayed motor development, hypotonia and weakness, respiratory weakness for which no non-invasive nocturnal ventilation yet at 19 years of age, limited walking distance (100 m), scolioisis	CM022836 Not reported
	10	NL 3508	Muscle biopsy	Netherlands	1.5 years	c.[713dupA];[ 1332_1334del] p.[(N238fs)];[(N444del)]	Delayed motor development, hypotonia and weakness, respiratory weakness for which non-invasive nocturnal ventilation since 10 years of age, intermittent wheelchair use	CI022931
	11	Den 01	Muscle biopsy	Denmark	14 years	c.[446dupC];[943G>A] p.[(P149fs)];[(G315S)]	24-hr ventilator, rigid spine, spine operation age 30 years. Wheelchair bound since age 25.	CI1111271
	12	Den 02	Muscle biopsy	Denmark	7 years	c.[893T>C];[1396C>T] p.[(L298P)];[(R466W)]	Nocturnal ventilator, rigid spine, scoliosis operation age 19, wheelchair user, but can walk small distances	CM174139 CM174140
	13	Den 03	Muscle biopsy	Denmark	10 years	c.[943G>A];[943G>A] p.[(G315S)];[(G315S)]	Nocturnal ventilator, rigid spine, wheelchair user, but can walk small distances.	CM022836
	14	Den 04	Muscle biopsy	Denmark	14 years	c.[713 dup];[943G>A] p.[(N238fs)];[(G315S)]	Rigid spine, normal lung function, proximal weakness, reduced walking distance (1 km)	CI1111271 CM022836
	15	BOS1457-1	Muscle biopsy	USA	3 years	c.[1A>G];[943G>A], p.[(M1V)];[(G315S)]	6 year female w/ moderate hypotonia at birth, delayed motor milestones, dysarthria. Currently ambulant for short distances, uses manual wheelchair for longer. On nocturnal ventilation by BiPAP	CM022835 CM022836
	16	CH 01	Muscle biopsy	Switzerland		c.[683_689dup];[ 683_689dup] p.[(M230fs)];[(M230fs)]		CI147558
	17	UK 852A	Muscle cells	U.K.	8 years	c.[827_829dup];[ 827_829dup] p.[(A276_C277insS)]:[(A276_C277insS)]	Presented aged 8 with joint laxity and frequent falls.. At age 14 presents: Motor difficulties. Spinal rigidity. Neck muscle tightness. Short stature. Nocturnal hypoventilation - under BiPAP (started at age 11).	CI160952
	18	UK L1753	Muscle cells	U.K	2 years	c.[802C>T];[1406G>A] p.[(R268C)];[(R469Q)]	At age 4 presents: early onset scoliosis, currently being treated in brace. Axial weakness, hypermobility, hypotonia, slow weight gain, and abnormal sleep study, with plans to initiate BiPap nocturnal ventilator support.	CM114823 CM091416

All variants listed relative to SELENON reference sequence NM_020451.2

^#All previously unreported variants have been submitted to the LOVD database (http://www.LOVD.nl/SEPN1 ; all variants: http://databases.lovd.nl/shared/variants/SEPN1/unique)

^†The HGMD column shows the ID accession numbers of all listed previously reported variants.