PMC10070974_01
Family pedigree of patient 1. NEB-nebulin gene variant c. 11969A>C; CREBBP: cyclic adenosine monophosphate response element binding protein gene variant c.5600G>A; NPC2: NPC intracellular cholesterol transporter 2 gene variant c.420-422delCTG. Proband (P) IV1 (purple): patient 1 was diagnosed with nemaline myopathy type 2 (NEB gene homozygous c.11969A>C) and heterozygous for CREBBP variant c.5600G>A; IV6 (red) diagnosed with Niemann-Pick disease type C2 (NPC2 gene homozygous c.420-422delCTG). (IV-2 & IV-3)* are dizygotic twins through pre-implantation genetic testing for monogenic disorders (PGT-M).
fgene-14-1098102-g001.jpg
PMC10070974_01_fgene-14-1098102-g001.jpg
F1
Patient 1, a boy aged 7 years and 10 months is the first child of a healthy and consanguineous Arab couple (first-degree paternal cousins) (Figure 1).
Phenotype of patient 1. (A) Clinical phenotype at the age of 2 days: bilateral generalized arthrogryposis with predominant bilateral elbow and knee flexion contractures, right foot talipes equinovarus, and left foot vertical talipes. (B) Clinical phenotype at the age of 18 months: wide forehead, bitemporal narrowing, hypertelorism, bilateral epicanthus, divergent strabismus, small depressed nasal bridge, small nose, short columella, anteverted nares, smooth and long filtrum, micrognathia, myopathic face appearance with facial muscle weakness, wide and opened mouth with an everted lower lip, high arched palate, small and anterior rotated ears with smooth helix and antihelix, and anterior and uplifted ear lobules. (C) Clinical phenotype at the age of 7 years and 10 months: myopathic facies with the same previous particularities, high-arched palate, overcrowded teeth, abnormal dental eruption, generalized thin build, hyperlordotic spine, mild elbow and knee contraction bilateral with hypotrophy of calf muscles, more marked on the left side, and overlapping second and third toes bilaterally. (D) MRI lower-limb (plain) (R-right, L-left): T1 axial of the calves showing mild atrophy of right gastrocnemius (c) and right soleus (d) muscles and subtle fatty infiltration; moderate atrophy of left anterior tibialis (a), posterior tibialis (b), gastrocnemius (c), and peroneal (e) muscles with prominent fatty infiltration; with a relative increase of the subcutaneous fat thickness in the left calf compared to the right one.
fgene-14-1098102-g002.jpg
PMC10070974_01_fgene-14-1098102-g002.jpg
F2
Bilateral generalized arthrogryposis with elbow and knee flexion contractures, right foot talipes equinovarus, left foot vertical talipes, inguinal hernia, bilateral cryptorchidism, and hypotonia were observed at birth (Figure 2A). Particular dysmorphic craniofacial features were observed (Figure 2B), which included a wide forehead, bitemporal narrowing, hypertelorism, bilateral epicanthus, divergent strabismus, a small depressed nasal bridge, a small nose, a short columella, anteverted nares, a smooth and long philtrum, micrognathia, a myopathic facial appearance with facial muscle weakness, a wide and opened mouth with an everted lower lip, a high arched palate, small and anteriorly rotated ears with a smooth helix and antihelix, anterior and uplifted ear lobules, generalized muscle weakness, dropped shoulders, overlapping second and third toes bilaterally, dysphagia, generalized hypotonia, and motor and speech delays. At the last visit to the genetic clinic at 7 years and 10 months of age (Figure 2C), his weight was 18 kg (1st percentile), his height was 117 cm (5th percentile), and his head circumference was 50 cm (5th percentile). The left anterior and posterior tibialis, peroneal and gastrocnemius muscles showed predominant atrophy, with a relative increase in subcutaneous fat thickness (Figure 2D).
PMC10070974_02
Family pedigree of patient 2. KLHL40: Kelch-like family member 40 gene variant c.1405G>A; FAT4: FAT atypical cadherin 4 gene variant c.13178A>T. Proband (P) IV5 (blue): patient 2 was diagnosed with nemaline myopathy type 8 (KLHL40 gene homozygous c.1405G>A), FAT4 gene homozygous c.13178A>T. The couple II-2 & II-3 are 2nd-degree relatives. IV-2: a full-term neonatal death after 24 h, unknown cause; IV-3: a 2nd-trimester intrauterine fetal death (IUFD) at 16 gestational weeks, unknown cause.
fgene-14-1098102-g003.jpg
PMC10070974_02_fgene-14-1098102-g003.jpg
F3
Patient 2 was a 10-week-old girl and the sixth child of a healthy, consanguineous Arab couple (first-degree paternal cousins) who had previously lost a pregnancy by second-trimester intrauterine fetal death and a child with severe congenital hypotonia and arthrogryposis by early neonatal death (Figure 3).
Phenotype of patient 2. (A) Clinical phenotype at the age of 1 day: craniofacial dysmorphism with narrowing of the bitemporal diameter, myopathic facies, exophthalmia, bilateral epicanthal fold, wide and depressed nasal bridge, short nose, vertical nostrils, long smooth philtrum, thin lips, micrognathia, microtia, short neck, small chest and rib cage, arthrogryposis with joint stiffness of the upper and lower limbs, right wrist with ulnar deviation, flexion of the left fingers, marked hip abduction, and talipes equinovarus. (B) X-ray skeletal survey: right mid-shaft humeral and right proximal femoral dislocated non-communicated fractures. (C) Muscle biopsy (left thigh) hematoxylin and eosin staining 40X: variation in muscle fiber size with degenerative changes. (D) Muscle biopsy (left thigh) Gomori trichrome stain 40X: degenerative muscle fibers containing red to purple rod inclusions in sarcoplasm.
fgene-14-1098102-g004.jpg
PMC10070974_02_fgene-14-1098102-g004.jpg
F4
Physical examinations revealed severe hypotonia and diminished deep tendon reflexes (Figure 4A). Multiple congenital anomalies were observed, including craniofacial dysmorphism with narrowing of the bitemporal diameter, myopathic facies, exophthalmia, a bilateral sluggish pupillary reflex with bulbar muscle weakness, a bilateral epicanthal fold, a wide and depressed nasal bridge, a short nose, vertical nostrils, a long and smooth philtrum, thin lips, micrognathia, microtia, a short neck, a small chest and rib cage, arthrogryposis with joint stiffness of the upper and lower limbs, a right wrist with ulnar deviation, flexion of the left fingers, marked hip abduction, talipes equinovarus, right mid-shaft humeral and right proximal femoral dislocated non-communicated fractures (Figure 4B), and hypoplastic genitalia. Variations in muscle fiber size with degenerative changes were visualized after hematoxylin and eosin staining of a skeletal muscle biopsy sample (Figure 4C). A high-power microscopic view after Gomori trichrome staining revealed red to purple rod inclusions in the sarcoplasm of degenerative muscle fibers (Figure 4D), linking the molecular genetic result to the muscular pathology features of NMs.