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Table 1 Comparison of the clinical phenotype of patients with SMG9 mutation reported by other groups

From: Identification of a novel compound heterozygous SMG9 variants in a Chinese family with heart and brain malformation syndrome using whole exome sequencing

Patients clinical data Our patient Altuwaijri et al. [12] Lemire et al. [11] Shaheen et al. [9] Lecoquierre et al. [10] Rahikkala et al. ([13], 5 patients)
Proband Affected sister Patient 1 Patient 2 Family I Family II-proband Family II-proband's first cousin
Variants in SMG9 (NM_019108.3) c.947A>G (p.His316Arg) and c.1318_1319delAG (p.Ser440*) c.701+4A>G (p.Tyr197Aspfs*10) c.1508G>C (p.Trp503Ser) c.520_521delCC (p.Pro174Argfs*12) c.701+4A>G (p.Tyr197Aspfs*10) c.1177C>T (p.Gln393*) c.551T>C (p.Val184Ala)
Gender Male Female Male Female Female Female Female Female Female Male
Age at last examination 5 year 10 years Died at 25 months Died at 1 h after birth 7 years Died at 7 weeks Died at 7 weeks 8 years 5 years ≥ 25 years in all the 5 patients
Neurodevelopment Severe ID Severe ID Global developmental delay NA Severe ID NA Global developmental delay Global developmental delay Severe psychomotor developmental delay 1/5 mild ID, 3/5 moderate ID, 1/5 borderline mild/moderate ID
Height, weight, head circumference 110.3 cm (50%, 0.0 SD), 20.2 kg (+ 0.4SD), 50 cm (− 0.5SD) 132.1 cm (10%, − 1.1SD), 31.2 kg (49.5%, 0.0SD) 74 cm (< 1%, − 3.7SD), 8.9 kg (< 1%, − 3.1SD), 44 cm (< 1%, − 3.2SD) NA 118.5 cm (30%), 25.1 kg (75%), 49.5 cm (25%) 44 cm (− 2.4SD), 2.130 kg (5%), 31.5 cm (− 2.2SD) 47 cm (15%, − 2.2SD), 2.26 kg, 32 cm (− 1.8SD) 69 cm (− 4.8SD), 6.3 kg (− 5.2SD), 39 cm (− 6SD) All three metrics were less than 3SD at the age of 2.5 years 3/5 short stature, 2/5 microcephaly
Age of walking 31 months but continues to exhibit an unsteady gait 35 months but continues to exhibit an unsteady gait NA NA 7 years but walk with a walker and ankle foot orthosis NA NA Unstable to sit alone Inability to walk ≤ 20 month
Development of speech and language skills No meaningful language Nonverbal NA NA Nonverbal NA NA Nonverbal Nonverbal Markedly delayed
Behavioral anomalies Recurrent stereotypical body rocking, hand flapping and spinning Recurrent hand flapping   NA Recurrent hand flapping and stereotypical body rocking      
Brain radiologic features Mild generalized brain atrophy hypomyelination, and small globus pallidus and putamen Not performed Brain atrophy, abnormally shaped lateral ventricles, thin corpus callosum, cerebellar and pontine atrophy with flattening of the pons ventral aspect, diffuse Not performed Normal Dandy–Walker malformation Brain atrophy, decreased myelination, and Dandy–Walker malformation Generalized brain atrophy, prominent ventricular system and thin corpus callosum Enlarged fourth ventricle with dysmorphism, a parieto-occipital junctional stroke, thin corpus callosum, a cavum septum pellucidum, and a Blake's pouch cyst 1/5 abnormal
2/5 normal
Feeding difficulty Yes Yes Yes NA Yes     Yes Yes
Muscular hypotonia Yes Yes Yes NA Yes NA Yes Yes Yes 2/5 abnormal
Ocular anomalies Duane syndrome Poor vision Bilateral sutural cataract NA Bilateral Duane syndrome type III, high hyperopia, and astigmatism Microphthalmia Microphthalmia   Hypertelorism, ptosis, and bilateral cataracts 4/5 abnormal
Cardiovascular Atrial septal defect and VSD VSD, hypoplastic tricuspid valve Interrupted inferior vena cava, a small ASD with left to right shunt Ectopia cordis ASD and a large perimembranous VSD Interrupted aortic arch, hypoplastic tricuspid and aortic valves, large muscular VSD Large VSD VSD VSD, aortic valve bicuspidy and aortic dilatation 1/5 abnormal
4/5 normal
Infections No No Yes NA Yes Yes    Yes Yes
Facial dysmorphic fetaures Broad nasal bridge, low set malformed ears and left-sided ptosis, prominent forehead Broad nasal bridge, low set malformed ears, prominent forehead Microretrognathia, anteverted nares, and hypertelorism, unilateral ear malformation and bilateral external auditory canal stenosis NA Long and oval face, narrow mouth, bifrontal narrowing with frontal bossing, prominent nose with bulbous tip, and high anterior hairline Prominent forehead and occiput, low set malformed ears, wide anterior fontanelle, depressed nasal bridge and anteverted nares, high arched palate Narrow forehead, prominent metopic suture, posteriorly rotated ears with attached lobules, hypertelorism, small eyes, broad nasal bridge, full and everted lower lip, right-sided cleft lip Dysmorphic features Left cleft lip and palate, transient frontal white hair lock, bi-temporal retraction with frontal bossing, upslanting palpebral fissures with hypertelorism, broad nasal bridge, midface hypoplasia, low-set posteriorly rotated ears with attached lobules, Widow's peak Abnormal
  1. ID intellectual disability, SD standard deviation from the mean, ASD atrial septal defect, VSD ventricular septal defect, NA not available