Muscle and bone characteristics of a Chinese family with spinal muscular atrophy, lower extremity predominant 1 (SMALED1) caused by a novel missense DYNC1H1 mutation

Table 1 Primary clinical characteristics of the proband and his affected family members

	Proband	Mother	Uncle 1	Uncle 2	Reference
Sex	Male	Female	Male	Male	/
Age at the first visit (years)	8	33	42	34	/
Height (cm) (Z-score)	116 (− 2.20)	163	N.A.	168	/
Weight (kg) (Z-score)	17.7 (− 1.65)	40	N.A.	N.A.	/
Head circumference (cm)	52	52	N.A.	N.A.	/
Foot deformity	Talipes calcaneovarus	Pes cavus	Pes cavus	Pes cavus	/
Motor ability	Complete loss	Delayed	Delayed	Delayed	/
Gait	Unable to walk	Waddling gait	Waddling gait	Waddling gait	/
Muscle weakness and atrophy	Severe	Mild	Mild	Mild	/
Deep tendon reflexes	Weakened	Weakened	N.A.	N.A.	/
Sensory disturbances	No	No	No	No	/
Cognitive impairment	No	No	No	No	/
Fragility fractures	No	No	No	No	/
Creatine kinase (U/l)	91	N.A.	N.A.	N.A.	21–190
Creatine kinase isoenzymes (U/l)	22.3	N.A.	N.A.	N.A.	0.0–25.0
Calcium (mmol/l)	2.34	N.A.	N.A.	N.A.	2.25–2.75^a
Phosphate (mmol/l)	1.53	N.A.	N.A.	N.A.	1.29–1.94^a
ALP (U/l)	213	N.A.	N.A.	N.A.	116–380^a
25OHD (ng/ml)	29.62	N.A.	N.A.	N.A.	≥ 0.0
PTH (pg/ml)	15	N.A.	N.A.	N.A.	15–65
OC (ng/ml)	96.49	N.A.	N.A.	N.A.	53.6–183.7^b
β-CTX (ng/l)	2593.00	N.A.	N.A.	N.A.	1090–2940^b
L1–L4 BMD (g/cm²) (Z-score)	0.654 (0.6)	N.A.	N.A.	N.A.	/
Left femur neck BMD (g/cm²) (Z-score)	0.754 (0.3)	N.A.	N.A.	N.A.	/

Abbreviations: 25OHD, 25-hydroxyvitamin D; ALP, alkaline phosphatase; β-CTX, beta cross-linked C-terminal telopeptide of type 1 collagen; BMD, bone mineral density; N.A., not available; OC, osteocalcin; PTH, parathyroid hormone
^aReference for children [39]
^bReference for boys between the ages of 8 and 9.9 years [40]

ISSN: 1755-8794