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| Severe microcephaly v4.23 | GRM7 |
Achchuthan Shanmugasundram changed review comment from: PMID:32286009 reported eleven individuals from six unrelated families identified with three different biallelic variants and presenting with a neurodevelopmental disorder comprising severe to profound global developmental delays, intellectual disability, seizures, hypotonia, microcephaly and brain abnormalities. This is also supported by functional evidence from knockout mouse models, where absence of metabotropic glutamate receptor 7 alters the phenotypes within the domains of social behavior, associative learning, motor function, epilepsy and sleep (PMID:32248644). This gene has also been associated with relevant phenotypes in both OMIM (MIM #618922) and in Gene2Phenotype (with 'strong' rating in the DD panel). Sources: Literature; to: PMID:32286009 reported eleven individuals from six unrelated families identified with three different biallelic variants and presenting with a neurodevelopmental disorder comprising severe to profound global developmental delays, intellectual disability, seizures, hypotonia, microcephaly and brain abnormalities. Head circumference measurements at time of last visit were available in eight individuals (from six families) and were consistent with microcephaly (−3.8 to −2.7 SD from mean for age). Of these four individuals from three families had severe microcephaly (head circumference beyond 3 SD from mean for age). This gene has also been associated with relevant phenotypes in both OMIM (MIM #618922) and in Gene2Phenotype (with 'strong' rating in the DD panel). Sources: Literature |
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| Severe microcephaly v4.23 | GRM7 |
Achchuthan Shanmugasundram gene: GRM7 was added gene: GRM7 was added to Severe microcephaly. Sources: Literature Mode of inheritance for gene: GRM7 was set to BIALLELIC, autosomal or pseudoautosomal Publications for gene: GRM7 were set to 2248644; 32286009 Phenotypes for gene: GRM7 were set to Neurodevelopmental disorder with seizures, hypotonia, and brain abnormalities, OMIM:618922 Review for gene: GRM7 was set to GREEN Added comment: PMID:32286009 reported eleven individuals from six unrelated families identified with three different biallelic variants and presenting with a neurodevelopmental disorder comprising severe to profound global developmental delays, intellectual disability, seizures, hypotonia, microcephaly and brain abnormalities. This is also supported by functional evidence from knockout mouse models, where absence of metabotropic glutamate receptor 7 alters the phenotypes within the domains of social behavior, associative learning, motor function, epilepsy and sleep (PMID:32248644). This gene has also been associated with relevant phenotypes in both OMIM (MIM #618922) and in Gene2Phenotype (with 'strong' rating in the DD panel). Sources: Literature |
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| Severe microcephaly v4.18 | TRA2B |
Achchuthan Shanmugasundram changed review comment from: This gene has already been associated with phenotypes in Gene2Phenotype (with 'moderate' rating in the DD panel), but not in OMIM. Sources: Literature; to: PMID:36549593 reported 12 individuals from 11 unrelated families identified with 11 different heterozygous variants in TRA2B gene. The variants arose de novo in 10 families, while the variant was inherited from father to son in one family. 6 variants were expected to disrupt the translation start site in exon 1 (start-loss variants), 3 were expected to disrupt the splicing process at the exon 2/3 boundary (splice-affecting variants), and the remaining 2 were expected to produce a premature stop codon (truncating variants). These patients presented with a neurodevelopmental disorder comprising developmental delay/ intellectual disability (in all patients), axial or global hypotonia (10 patients), delayed motor milestones (all patients), behavioural issues (8 patients), speech impairment (9 patients), epilepsy (7 patients, initial presentation as infantile spasms in 6 and unclassified epileptic encephalopathy in 1), brain abnormalities (10 patients) and microcephaly (5 patients). Of 5 unrelated cases with microcephaly, only two cases had severe microcephaly (head circumference beyond 3 standard deviations below the mean for the age). In addition, functional studies in mice showed that heterozygous knockout mice developed normal, while complete knockout mice cannot develop embryonically. This gene has already been associated with phenotypes in Gene2Phenotype (with 'moderate' rating in the DD panel), but not in OMIM. Sources: Literature |
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| Severe microcephaly v2.247 | ARCN1 |
Ivone Leong changed review comment from: Comment on publications: PMID:27476655. OMIM description of the patients, "exhibited rhizomelic short stature (4/4) as well as microcephaly (3/4), micrognathia (4/4), laxity of the small joints (3/4), and developmental delay (4/4). Other variable features included posterior cataract (1/4), cleft palate (1/4), ventricular septal defect (1/4), cryptorchidism (1/2), seizures (1/4), and autism (1/4)." Additional publications. PMID: 31075182 describes a 5th case with de novo loss-of-function variant in ARCN1. Head circumference at birth (prematurely after 33 + 3 weeks of pregnancy) was 27.3 cm (<3rd percentile). The publication says the patient presented with microcephaly; however, I cannot find any recent head circumference measurements (child is 23 months old). From the paper "we report a de novo loss-of-function mutation in the delta-COP subunit of COPI, associated with microcephaly, retrognathia, muscular hypotonia, short stature, rhizomelic shortening, and transiently hypoglycosylation during febrile infections." PMID: 33154040; to: Comment on publications: PMID:27476655. OMIM description of the patients, "exhibited rhizomelic short stature (4/4) as well as microcephaly (3/4), micrognathia (4/4), laxity of the small joints (3/4), and developmental delay (4/4). Other variable features included posterior cataract (1/4), cleft palate (1/4), ventricular septal defect (1/4), cryptorchidism (1/2), seizures (1/4), and autism (1/4)." Additional publications. PMID: 31075182 describes a 5th case with de novo loss-of-function variant in ARCN1. Head circumference at birth (prematurely after 33 + 3 weeks of pregnancy) was 27.3 cm (<3rd percentile). The publication says the patient presented with microcephaly; however, I cannot find any recent head circumference measurements (child is 23 months old). From the paper "we report a de novo loss-of-function mutation in the delta-COP subunit of COPI, associated with microcephaly, retrognathia, muscular hypotonia, short stature, rhizomelic shortening, and transiently hypoglycosylation during febrile infections." PMID: 33154040 describes another case. "3.5-yr-old Caucasian/Peruvian/Native American boy with microcephaly, severe global developmental delay, and multiple congenital abnormalities. At birth he was documented to have a small ventricular septal defect (which was closed by 3 wk), a patent foramen ovale, rhizomelic shortening of extremities on clinical examination, pectus carinatum, and underdeveloped genitalia including severe penoscrotal hypospadias and cryptorchidism." OFC at birth was just above 10th centile, at 3.5 yr OFC is below 3rd centile but no actual measurements were given. Microarrays identified a 95-kb loss at 12q23.2 including exons 1–4 of the NUP37 gene and exons 1–9 of the PARPBP gene, which were deemed nondiagnostic (neither parents had this deletion). A heterozygous variant was also found in HSPG2 (c.9893 C > T, p. Pro3298Leu). Biallelic variants in this gene is associated with skeletal disorders that did not fit the patient's phenotype and as the patient is heterozygous for a variant in HSPG2 it was deemed that this variant was not causative. WGS identified a de novo splice variant in ARCN1. mRNA studies showed that the variant caused retention of part of an intron in the transcript. The authors deemed the ARCN1 variant as the causative variant in this patient. |
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| Severe microcephaly v2.247 | ARCN1 |
Ivone Leong Added comment: Comment on publications: PMID:27476655. OMIM description of the patients, "exhibited rhizomelic short stature (4/4) as well as microcephaly (3/4), micrognathia (4/4), laxity of the small joints (3/4), and developmental delay (4/4). Other variable features included posterior cataract (1/4), cleft palate (1/4), ventricular septal defect (1/4), cryptorchidism (1/2), seizures (1/4), and autism (1/4)." Additional publications. PMID: 31075182 describes a 5th case with de novo loss-of-function variant in ARCN1. Head circumference at birth (prematurely after 33 + 3 weeks of pregnancy) was 27.3 cm (<3rd percentile). The publication says the patient presented with microcephaly; however, I cannot find any recent head circumference measurements (child is 23 months old). From the paper "we report a de novo loss-of-function mutation in the delta-COP subunit of COPI, associated with microcephaly, retrognathia, muscular hypotonia, short stature, rhizomelic shortening, and transiently hypoglycosylation during febrile infections." PMID: 33154040 |
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| Severe microcephaly v2.103 | PPP1R35 |
Arina Puzriakova gene: PPP1R35 was added gene: PPP1R35 was added to Severe microcephaly. Sources: Other watchlist tags were added to gene: PPP1R35. Mode of inheritance for gene: PPP1R35 was set to BIALLELIC, autosomal or pseudoautosomal Phenotypes for gene: PPP1R35 were set to Primary microcephaly Added comment: Conference poster (Genomics of Rare Disease 2021) - 'Biallelic frameshift indel in PPP1R35 as a cause of primary microcephaly' by Dawood et al, Baylor College of Medicine - Proband from a Turkish consanguineous family with primary microcephaly (-4.3 SD at birth, -6.1 SD by 42 months) and GDD. Brain imaging showed thinning of corpus collosum, mild cerebellar volume loss, increased extra-axial CSF spaces, pachygyria, dysmorphic ventricular system and delayed myelination of the internal capsule. Exome sequencing revealed a biallelic frameshifting indel in the PPP1R35 gene (c.753_*3delGGAAGCGTAGACCinsCG; p.Trp251Cysfs*22), resulting in deletion of the canonical stop codon in the last exon. Sequencing of unaffected parents and 2 unaffected sibs confirmed segregation with the phenotype. Droplet digital PCR demonstrated expression of mutant mRNA, with comparable gene expression levels observed for mutant and wild-type alleles in fibroblasts. Authors note a second Iranian consanguineous family in literature with two sibs with microcephaly and the same, p.Trp251Cysfs*22 variant - however, this paper could not be found in PubMed. Sources: Other |
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| Severe microcephaly v2.87 | AP4E1 |
Arina Puzriakova changed review comment from: Comment on list classification: New gene added by Zornitza Stark. Rating Amber but there is sufficient evidence to rate Green at the next GMS panel update (added 'for-review' tag) At least 21 individuals from 11 unrelated families reported in literature with variants in this gene (PMID: 32979048). Microcephaly was observed in 14/16 cases but details regarding head circumference were mostly unavailable. At least 5 individuals (2 families) had microcephaly of relevant severity to this panel (OFC ≤ -3 SD) (see PMIDs: 21620353 and 20972249).; to: Comment on list classification: New gene added by Zornitza Stark. Rating Amber with recommendation of review by the GMS team to assess whether there is sufficient evidence to support a Green rating (added 'for-review' tag) At least 21 individuals from 11 unrelated families reported in literature with variants in this gene (PMID: 32979048). Microcephaly was observed in 14/16 cases but precise details regarding head circumference were mostly omitted (no relevant info was provided for the remaining 5 patients). However, at least 5 individuals (2 families) had microcephaly of relevant severity to this panel (OFC ≤ -3 SD) (see PMIDs: 21620353 and 20972249). |
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| Severe microcephaly v2.44 | LMNB2 | Sarah Leigh edited their review of gene: LMNB2: Added comment: Not associated with a relevant phenotype in OMIM or in Gen2Phen. PMID 33033404 reports five individuals with heterozygous variants in LMNB2. One of these cases was de novo for c.160A>C p.N54H (NM_032737.4) and the remaining cases had c.1192G>A, p.Glu398Lys (NM_032737.4), which was shown to be de novo in two cases, inherited from the unaffected mother (who was mosaic for the variant) and the inheritance in the remaining case was not established. All of these cases had moderate to severe developmental delay and microcephaly.; Changed rating: GREEN | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Severe microcephaly v2.20 | SMO |
Zornitza Stark gene: SMO was added gene: SMO was added to Severe microcephaly. Sources: Expert list Mode of inheritance for gene: SMO was set to BIALLELIC, autosomal or pseudoautosomal Publications for gene: SMO were set to 32413283 Phenotypes for gene: SMO were set to Microcephaly, congenital heart disease, polydactyly, aganglionosis Review for gene: SMO was set to GREEN gene: SMO was marked as current diagnostic Added comment: Bi-allelic loss-of-function variations in SMO reported in seven individuals from five independent families. Wide phenotypic spectrum of developmental anomalies affecting the brain (hypothalamic hamartoma and microcephaly), heart (atrioventricular septal defect), skeleton (postaxial polydactyly, narrow chest, and shortening of long bones), and enteric nervous system (aganglionosis). Sources: Expert list |
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| Severe microcephaly v2.12 | NCAPD2 |
Arina Puzriakova gene: NCAPD2 was added gene: NCAPD2 was added to Severe microcephaly. Sources: Literature Mode of inheritance for gene: NCAPD2 was set to BIALLELIC, autosomal or pseudoautosomal Publications for gene: NCAPD2 were set to 27737959; 28097321; 31056748 Phenotypes for gene: NCAPD2 were set to Microcephaly 21, primary, autosomal recessive, 617983 Review for gene: NCAPD2 was set to GREEN Added comment: Associated with phenotype in OMIM and a possible gene for Microcephaly with short stature in G2P. PMID: 27737959 (2016) - A homozygous splice site variant (c.4120+2T>C, p.Asp1374Glyfs*29) in NCAPD2 was detected in a 3-year-old male with severe microcephaly (OFC -11.9 SD), severe ID, autistic-like behaviours, and no speech. The variant was found in a heterozygous state in both unaffected parents and was not present in the ExAC database. Functional studies indicated that the variant disrupted condensin-dependent mitotic chromosome integrity, providing supporting evidence for pathogenicity. PMID: 28097321 (2017) - In two affected cousins from a consanguineous family with mild ID, intrauterine growth retardation, short stature, and microcephaly. Homozygous missense variants were found in NCAPD2 (c.23T>C, p.Phe8Ser), but also in ENO2 (c.710C>T, p.Thr237Met). Variants segregated with disease in the family, but no further functional studies were undertaken of the variants or patient cells. PMID: 31056748 (2019) - In a 13-year-old female with severe microcephaly (OFC < -3), mild ID (IQ 59), poor learning performance, sloping forehead and reduced cerebral cortex size, exome sequencing revealed a homozygous variant in NCAPD2 (c.3477+2T>C, p.Gly1160Valfs*16). Progressive microcephaly was also apparent in a sibling of the proband, a male fetus which was terminated at 34 weeks of pregnancy. The same homozygous variant was identified in the fetus, while parents were heterozygotes and an unaffected brother was homozygous for the other allele. No further functional studies of the variant or patient cells were performed. Sources: Literature |
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| Severe microcephaly v1.62 | NIN | Louise Daugherty reviewed gene: NIN: Rating: AMBER; Mode of pathogenicity: ; Publications: ; Phenotypes: ; Mode of inheritance: | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Severe microcephaly v1.61 | NIN | Louise Daugherty Source NHS GMS was added to NIN. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Severe microcephaly v1.37 | ISCA-37425-Gain |
Louise Daugherty Region: ISCA-37425-Gain was added Region: ISCA-37425-Gain was added to Primary Microcephaly - Microcephalic Dwarfism Spectrum. Sources: ClinGen,Expert Review Green Mode of inheritance for Region: ISCA-37425-Gain was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown Publications for Region: ISCA-37425-Gain were set to 23913520; 23599694 Phenotypes for Region: ISCA-37425-Gain were set to Microcephaly, short stature and developmental delay; short stature, microcephaly, learning disability or mild to moderate ID, and distinctive facial features comprising periorbital fullness, short palpebral fissures, a long nose with broad or long nasal tip, a smooth philtrum and a thin upper lip vermilion. Behavioral problems, ocular and minor hand anomalies may be associated. |
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| Severe microcephaly v1.37 | ISCA-37406-Loss |
Louise Daugherty Region: ISCA-37406-Loss was added Region: ISCA-37406-Loss was added to Primary Microcephaly - Microcephalic Dwarfism Spectrum. Sources: ClinGen,Expert Review Green Mode of inheritance for Region: ISCA-37406-Loss was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown Publications for Region: ISCA-37406-Loss were set to 10573006; 16783566 Phenotypes for Region: ISCA-37406-Loss were set to PMID: 10573006 death in infancy, accessory spleens, hypoplastic left heart, abnormal pulmonary lobulation, renal agenesis (patient 1), severe neonatal seizures (patient 2). PMID 16783566: failure to thrive, life-threatening malformations, and/or critical infections, and all died in infancy (5 weeks, 7 months, and 9 months, respectivelyFrom Genetics Home Reference: short stature, moderate to severe intellectual disability, distinctive facial features, and broad thumbs and first toes; 610543 |
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| Severe microcephaly | NIN | Rebecca Foulger marked NIN as ready | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Severe microcephaly | NIN | Rebecca Foulger commented on NIN | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||