Intellectual disability - microarray and sequencing
Gene: PPFIBP1
The rating of this gene has been updated to Green following NHS Genomic Medicine Service approval.Created: 11 Oct 2023, 9:34 a.m. | Last Modified: 11 Oct 2023, 9:34 a.m.
Panel Version: 5.286
Mode of inheritance
BIALLELIC, autosomal or pseudoautosomal
Comment on list classification: There is sufficient evidence for this gene to be promoted to GREEN rating at the next GMS update.Created: 3 May 2023, 5:03 p.m. | Last Modified: 3 May 2023, 5:03 p.m.
Panel Version: 5.93
As reviewed by Konstantinos Varvagiannis, all individuals (16 individuals from 12 families) reported in PMID:35830857 shared a core phenotype of global developmental delay/intellectual disability (GDD/ID) and epilepsy. 15 were affected by profound or severe GDD/ID (15/16). They had not acquired speech (15/16) and showed impaired motor development (15/16).
This gene has already been associated with relevant phenotypes in both OMIM (MIM #620024) and Gene2Phenotype (with 'strong' rating in the DD panel).Created: 3 May 2023, 4:50 p.m. | Last Modified: 3 May 2023, 5:09 p.m.
Panel Version: 5.93
Mode of inheritance
BIALLELIC, autosomal or pseudoautosomal
Phenotypes
Neurodevelopmental disorder with seizures, microcephaly, and brain abnormalities, OMIM:620024
Publications
Consider inclusion with green rating in the ID, epilepsy as well as other likely relevant gene panels (microcephaly, white matter disorders, corpus callosum abnormalities, intracerebral calficication disorders, malformations of cortical development, hereditary spastic paraplegia, growth failure in early childhood, etc) based on the summary below.
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Rosenhahn et al (2022 - PMID: 35830857) describe the phenotype of 16 individuals - belonging to 12 unrelated families - with biallelic PPFIBP1 pathogenic variants. Most (14/16) were born to consanguineous parents. One of these families was previously reported by Shaheen et al (2019 - PMID: 30214071) who first identified PPFIBP1 as a candidate gene for congenital microcephaly. In the current study, Rosenhahn also identified a fetus homozygous for a missense variant and similar features.
All individuals presented global DD/ID (16/16 - in 15 cases profound/severe) and epilepsy (16/16 - onset 1d-4y / median 2m - focal seizures in 11/16, epileptic spams in 7/16, generalized onset in 7/16, myoclonic in 6/16 - drug-resistant : 13/16). Almost all (15/16) had microcephaly, commonly congenital (9/16) and progressive (11/16). Other neurological findings included hypertonia (10/16), spastic tetraplegia (6/16), hypotonia (5/16), dystonic movements (3/16) or nystagmus (4/16). Brain abnormalities were identified in all investigated with MRI and included leukoencephalopathy (11/14) mostly periventricular, abnormal cortex morphology (7/14 - polymicrogyria 1, increased cortical thickness 4, pachygyria 3), cortical atrophy, corpus callosum hypoplasia (7/14). Intracranial calcifications were identified in all (9/9) investigated with CT scan. Abnormal growth was reported for several (SGA in 9/16, FTT 8/16, short stature 7/16) often associated with feeding difficulties (7/16). Other features incl. abnormal hearing (4/16), congenital heart defects (7/16), ophthalmologic findings (8/16), undescended testes (3/10). There were no overlapping facial features.
The fetus displayed similar features incl. SGA, microcephaly, intracranial calcifications.
Investigations incl. exome/genome sequencing (singleton or trio) with Sanger for confirmation/segregation of variants where necessary. Variable previous investigations incl. metabolic screening, TORCH screening, chromosomal studies (CMA) are mentioned in the supplement and were non-diagnostic. Additional candidate variants were identified in few cases although cases with plausible dual diagnoses (e.g. ind14) were not included in the overall phenotypic description.
9 pLoF variants (nonsense, frameshift, 1 splicing) predicted to lead to NMD were identified. There were no functional studies performed.
The missense variant c.2177G>T / p.Gly726Val (NM_003622.4) was predicted deleterious by in silico tools while the AA change causing severe steric problems upon modelling.
PPFIBP1 encodes PPFIA-binding protein 1 also known as liprin-β1. As the authors discuss: The liprin family of proteins comprises liprins α1 to 4 and liprin β1 and β2 in mammals. Liprin β1 is known to homodimerize and heterodimerize with α-liprins. In fibroblast cultures liprins β1 and α1 colocalize to cell membrane and periphery of focal adhesions. Members of the liprin-α fam. are scaffold proteins playing a role in synapse formation/signaling and axonal transport.
A ko model of the PPFIBP1 ortholog in C.elegans displayed abnormal locomotion behavior. In Drosophila, null-allele mutants resulted in altered axon outgrowth and synapse formation of R7 photoreceptors and reduced neuromuscular junction size (Refs provided in article).
Using a PPFIBP1/hlb-1 ko C.elegans model the authors demonstrated defects in spontaneous and light-induced behavior. Sensitivity of the worms to an acetylcholinesterase inhibitor (aldicarb) was suggestive of a presynaptic defect.
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There is currently no PPFIBP1 - associated phenotype in OMIM / G2P.
SysNDD lists PPFIBP1 among the ID genes (limited evidence based on the 3 sibs reported by Shaheen et al, 2019 - PMID: 30214071).
In PanelApp Australia the gene is listed with green rating for ID, epilepsy, microcephaly based on the medRxiv pre-print.
Sources: LiteratureCreated: 17 Jul 2022, 10:19 a.m.
Mode of inheritance
BIALLELIC, autosomal or pseudoautosomal
Phenotypes
Global developmental delay; Intellectual disability; Microcephaly; Seizures; Abnormality of brain morphology; Abnormality of the cerebral white matter; Cerebral calcification; Abnormal cortical gyration; Hypertonia; Spastic tetraplegia; Generalized hypotonia; Small for gestational age; Growth delay; Failure to thrive; Feeding difficulties; abnormal heart morphology; Hearing abnormality; Cryptorchidism; Abnormality of vision
Publications
Tag Q2_23_promote_green was removed from gene: PPFIBP1.
Source NHS GMS was added to PPFIBP1. Source Expert Review Green was added to PPFIBP1. Rating Changed from Amber List (moderate evidence) to Green List (high evidence)
Gene: ppfibp1 has been classified as Amber List (Moderate Evidence).
Gene: ppfibp1 has been classified as Amber List (Moderate Evidence).
Gene: ppfibp1 has been classified as Amber List (Moderate Evidence).
Gene: ppfibp1 has been classified as Amber List (Moderate Evidence).
Gene: ppfibp1 has been classified as Amber List (Moderate Evidence).
Phenotypes for gene: PPFIBP1 were changed from Neurodevelopmental disorder with seizures, microcephaly, and brain abnormalities, OMIM:620024 to Neurodevelopmental disorder with seizures, microcephaly, and brain abnormalities, OMIM:620024
Phenotypes for gene: PPFIBP1 were changed from Neurodevelopmental disorder with seizures, microcephaly, and brain abnormalities, OMIM:620024 to Neurodevelopmental disorder with seizures, microcephaly, and brain abnormalities, OMIM:620024
Phenotypes for gene: PPFIBP1 were changed from Neurodevelopmental disorder with seizures, microcephaly, and brain abnormalities, OMIM:620024 to Neurodevelopmental disorder with seizures, microcephaly, and brain abnormalities, OMIM:620024
Phenotypes for gene: PPFIBP1 were changed from Neurodevelopmental disorder with seizures, microcephaly, and brain abnormalities, OMIM:620024 to Neurodevelopmental disorder with seizures, microcephaly, and brain abnormalities, OMIM:620024
Phenotypes for gene: PPFIBP1 were changed from Neurodevelopmental disorder with seizures, microcephaly, and brain abnormalities, OMIM:620024 to Neurodevelopmental disorder with seizures, microcephaly, and brain abnormalities, OMIM:620024
Phenotypes for gene: PPFIBP1 were changed from Neurodevelopmental disorder with seizures, microcephaly, and brain abnormalities, OMIM:620024 to Neurodevelopmental disorder with seizures, microcephaly, and brain abnormalities, OMIM:620024
Phenotypes for gene: PPFIBP1 were changed from Neurodevelopmental disorder with seizures, microcephaly, and brain abnormalities, OMIM:620024 to Neurodevelopmental disorder with seizures, microcephaly, and brain abnormalities, OMIM:620024
Phenotypes for gene: PPFIBP1 were changed from Neurodevelopmental disorder with seizures, microcephaly, and brain abnormalities, OMIM:620024 to Neurodevelopmental disorder with seizures, microcephaly, and brain abnormalities, OMIM:620024
Phenotypes for gene: PPFIBP1 were changed from Neurodevelopmental disorder with seizures, microcephaly, and brain abnormalities, OMIM:620024 to Neurodevelopmental disorder with seizures, microcephaly, and brain abnormalities, OMIM:620024
Tag Q2_23_promote_green tag was added to gene: PPFIBP1.
Phenotypes for gene: PPFIBP1 were changed from Neurodevelopmental disorder with seizures, microcephaly, and brain abnormalities, OMIM:620024 to Neurodevelopmental disorder with seizures, microcephaly, and brain abnormalities, OMIM:620024
Phenotypes for gene: PPFIBP1 were changed from Global developmental delay; Intellectual disability; Microcephaly; Seizures; Abnormality of brain morphology; Abnormality of the cerebral white matter; Cerebral calcification; Abnormal cortical gyration; Hypertonia; Spastic tetraplegia; Generalized hypotonia; Small for gestational age; Growth delay; Failure to thrive; Feeding difficulties; abnormal heart morphology; Hearing abnormality; Cryptorchidism; Abnormality of vision to Neurodevelopmental disorder with seizures, microcephaly, and brain abnormalities, OMIM:620024
gene: PPFIBP1 was added gene: PPFIBP1 was added to Intellectual disability. Sources: Literature Mode of inheritance for gene: PPFIBP1 was set to BIALLELIC, autosomal or pseudoautosomal Publications for gene: PPFIBP1 were set to 35830857; 30214071 Phenotypes for gene: PPFIBP1 were set to Global developmental delay; Intellectual disability; Microcephaly; Seizures; Abnormality of brain morphology; Abnormality of the cerebral white matter; Cerebral calcification; Abnormal cortical gyration; Hypertonia; Spastic tetraplegia; Generalized hypotonia; Small for gestational age; Growth delay; Failure to thrive; Feeding difficulties; abnormal heart morphology; Hearing abnormality; Cryptorchidism; Abnormality of vision Penetrance for gene: PPFIBP1 were set to Complete Review for gene: PPFIBP1 was set to GREEN