scholarly journals Modifier Genes in Microcephaly: A Report on WDR62, CEP63, RAD50 and PCNT Variants Exacerbating Disease Caused by Biallelic Mutations of ASPM and CENPJ

Genes ◽  
2021 ◽  
Vol 12 (5) ◽  
pp. 731
Author(s):  
Ehtisham Ul Haq Makhdoom ◽  
Syeda Seema Waseem ◽  
Maria Iqbal ◽  
Uzma Abdullah ◽  
Ghulam Hussain ◽  
...  
Keyword(s):  
Neurological Disorders ◽  
Missense Variant ◽  
Seckel Syndrome ◽  
Primordial Dwarfism ◽  
Causal Variants ◽  
Multiplex Families ◽  
Intrafamilial Variability ◽  
Congenital Microcephaly ◽  
Biallelic Mutations ◽  
Deep Phenotyping

Congenital microcephaly is the clinical presentation of significantly reduced head circumference at birth. It manifests as both non-syndromic—microcephaly primary hereditary (MCPH)—and syndromic forms and shows considerable inter- and intrafamilial variability. It has been hypothesized that additional genetic variants may be responsible for this variability, but data are sparse. We have conducted deep phenotyping and genotyping of five Pakistani multiplex families with either MCPH (n = 3) or Seckel syndrome (n = 2). In addition to homozygous causal variants in ASPM or CENPJ, we discovered additional heterozygous modifier variants in WDR62, CEP63, RAD50 and PCNT—genes already known to be associated with neurological disorders. MCPH patients carrying an additional heterozygous modifier variant showed more severe phenotypic features. Likewise, the phenotype of Seckel syndrome caused by a novel CENPJ variant was aggravated to microcephalic osteodysplastic primordial dwarfism type II (MOPDII) in conjunction with an additional PCNT variant. We show that the CENPJ missense variant impairs splicing and decreases protein expression. We also observed centrosome amplification errors in patient cells, which were twofold higher in MOPDII as compared to Seckel cells. Taken together, these observations advocate for consideration of additional variants in related genes for their role in modifying the expressivity of the phenotype and need to be considered in genetic counseling and risk assessment.

Novel biallelic mutations in POLG gene: large deletion and missense variant associated with PEO

2021 ◽  
Author(s):  
Yan Lin ◽  
Jixiang Du ◽  
Wei Wang ◽  
Hong Ren ◽  
Dandan Zhao ◽  
...  
Keyword(s):  
Missense Variant ◽  
Large Deletion ◽  
Polg Gene ◽  
Biallelic Mutations

scholarly journals Variable Expressivity of the Beckwith-Wiedemann Syndrome in Four Pedigrees Segregating Loss-of-Function Variants of CDKN1C

Genes ◽  
2021 ◽  
Vol 12 (5) ◽  
pp. 706
Author(s):  
Angela Sparago ◽  
Flavia Cerrato ◽  
Laura Pignata ◽  
Francisco Cammarata-Scalisi ◽  
Livia Garavelli ◽  
...  
Keyword(s):  
Cellular Proliferation ◽  
Missense Variant ◽  
Abdominal Wall Defects ◽  
Loss Of Function ◽  
Nonsense Mutations ◽  
Molecular Defects ◽  
Variable Expressivity ◽  
Imprinting Disorder ◽  
Perinatal Lethality ◽  
Intrafamilial Variability

Beckwith-Wiedemann syndrome (BWS) is an imprinting disorder characterized by prenatal and/or postnatal overgrowth, organomegaly, abdominal wall defects and tumor predisposition. CDKN1C is a maternally expressed gene of the 11p15.5 chromosomal region and is regulated by the imprinting control region IC2. It negatively controls cellular proliferation, and its expression or activity are frequently reduced in BWS. In particular, loss of IC2 methylation is associated with CDKN1C silencing in the majority of sporadic BWS cases, and maternally inherited loss-of-function variants of CDKN1C are the most frequent molecular defects of familial BWS. We have identified, using Sanger sequencing, novel CDKN1C variants in three families with recurrent cases of BWS, and a previously reported variant in a woman with recurrent miscarriages with exomphalos. Clinical evaluation of the patients showed variable manifestation of the disease. The frameshift and nonsense variants were consistently associated with exomphalos, while the missense variant caused a less severe phenotype. Pregnancy loss and perinatal lethality were found in the families segregating nonsense mutations. Intrafamilial variability of the clinical BWS features was observed, even between siblings. Our data are indicative of severe BWS phenotypes that, with variable expressivity, may be associated with both frameshift and nonsense variants of CDKN1C.

scholarly journals Case Report: Recurrent Variant c.298 TA in CCN6 Gene Found in Progressive Pseudorheumatoid Dysplasia Patients From Patni Community of Gujarat: A Report of Three Cases

2021 ◽  
Vol 12 ◽  
Author(s):  
Harsh Sheth ◽  
Jhanvi Shah ◽  
Aadhira Nair ◽  
Premal Naik ◽  
Jayesh Sheth
Keyword(s):  
Genetic Disorder ◽  
Case Series ◽  
Missense Variant ◽  
Community Analysis ◽  
Gait Disturbance ◽  
Mutant Genotype ◽  
Progressive Pseudorheumatoid Dysplasia ◽  
First Case ◽  
Abnormal Posture ◽  
Biallelic Mutations

Biallelic mutations in the CCN6 gene are known to cause a rare genetic disorder—progressive pseudorheumatoid dysplasia (PPD). PPD is characterized by distinct joint deformities of interphalangeal joints, stiffness, gait disturbance, abnormal posture, and absence of inflammation, resulting in significant morbidity. The largest case series of PPD from India suggests c.233G>A and c.1010G>A to be the most common mutations in the CCN6 gene, although the distribution of these variants among endogamous communities in India has not been carried out. We here report three cases of PPD from three independent families belonging to the Patni community of Gujarat, a community known to practice endogamy. All three cases had short stature, gait disturbance, scoliosis, and interphalangeal joint deformities. Analysis by whole-exome sequencing in the first case showed the presence of a previously known, homozygous, missense variant c.298T>A (p.Cys100Ser) in exon 3 of the CCN6 gene in all cases. Due to all three families belonging to the same community, analysis by Sanger sequencing in the remaining two cases for the variant mentioned earlier showed both cases to be of homozygous mutant genotype. Unaffected family members, i.e., parents and siblings, were either heterozygous carriers or wildtype for the said variant. The present case series is the first report of a recurrent variant occurring across multiple PPD-affected individuals from unrelated families belonging to the same community from India.

Biallelic mutations in the TOGARAM1 gene cause a novel primary ciliopathy

2020 ◽  
pp. jmedgenet-2020-106833
Author(s):  
Valeria Morbidoni ◽  
Emanuele Agolini ◽  
Kevin C Slep ◽  
Luca Pannone ◽  
Daniela Zuccarello ◽  
...  
Keyword(s):  
Sensory Neurons ◽  
Developmental Disorders ◽  
Cleft Lip ◽  
Cleft Lip And Palate ◽  
Missense Variant ◽  
Causative Role ◽  
Biallelic Mutations ◽  
The Impact

BackgroundDysfunction in non-motile cilia is associated with a broad spectrum of developmental disorders characterised by clinical heterogeneity. While over 100 genes have been associated with primary ciliopathies, with wide phenotypic overlap, some patients still lack a molecular diagnosis.ObjectiveTo investigate and functionally characterise the molecular cause of a malformation disorder observed in two sibling fetuses characterised by microphthalmia, cleft lip and palate, and brain anomalies.MethodsA trio-based whole exome sequencing (WES) strategy was used to identify candidate variants in the TOGARAM1 gene. In silico, in vitro and in vivo (Caenorhabditis elegans) studies were carried out to explore the impact of mutations on protein structure and function, and relevant biological processes.ResultsTOGARAM1 encodes a member of the Crescerin1 family of proteins regulating microtubule dynamics. Its orthologue in C. elegans, che-12, is expressed in a subset of sensory neurons and localises in the dendritic cilium where it is required for chemosensation. Nematode lines harbouring the corresponding missense variant in TOGARAM1 were generated by CRISPR/Cas9 technology. Although chemotaxis ability on a NaCl gradient was not affected, che-12 point mutants displayed impaired lipophilic dye uptake, with shorter and altered cilia in sensory neurons. Finally, in vitro analysis of microtubule polymerisation in the presence of wild-type or mutant TOG2 domain revealed a faster polymerisation associated with the mutant protein, suggesting aberrant tubulin binding.ConclusionsOur data are in favour of a causative role of TOGARAM1 variants in the pathogenesis of this novel disorder, connecting this gene with primary ciliopathy.

scholarly journals Microcephalic osteodysplastic primordial dwarfism type I with biallelic mutations in the RNU4ATAC gene

2011 ◽  
Vol 82 (2) ◽  
pp. 140-146 ◽  
Author(s):  
R Nagy ◽  
H Wang ◽  
B Albrecht ◽  
D Wieczorek ◽  
G Gillessen- Kaesbach ◽  
...  
Keyword(s):  
Type I ◽  
Primordial Dwarfism ◽  
Biallelic Mutations

scholarly journals P.067 Phosphoserine aminotransferase (PSAT) deficiency: Imaging findings in a child with congenital microcephaly

2018 ◽  
Vol 45 (s2) ◽  
pp. S33-S33
Author(s):  
G Shapira Zaltsberg ◽  
H McMillan ◽  
E Miller
Keyword(s):  
Intractable Epilepsy ◽  
Mri Findings ◽  
Phosphoserine Aminotransferase ◽  
Magnetic Resonance Imaging Mri ◽  
Biochemical Testing ◽  
Congenital Microcephaly ◽  
Biallelic Mutations ◽  
Serine Biosynthesis ◽  
Torch Infections

Background: Serine deficiency disorders can result from deficiency in one of three enzymes. Deficiency of the second enzyme in the serine biosynthesis pathway, 3-phosphoserine aminotransferase (PSAT), has been reported in two siblings when the eldest was investigated for acquired microcephaly, progressive spasticity and intractable epilepsy. Methods: Our patient had neurological symptoms apparent at birth. Fetal magnetic resonance imaging (MRI) at 35 weeks gestation demonstrated microencephaly and simplification of the the gyration (anterior>posterior) which was confirmed upon subsequent post-natal MRI. Congenital microcephaly was apparent at birth. Results: PSAT deficiency was confirmed when exome sequencing identified biallelic mutations in PSAT1; c.44C>T, p.Ala15Val and; c.432delA, p.Pro144fs and biochemical testing noted low plasma serine 22 mcmol/L (normal 83-212 mcmol/L) and low CSF serine 10 mcmol/L (normal 22-61 mcmol/L). Despite oral serine and glycine supplementation at 4 months old the patient showed little neurodevelopmental progress and developed epileptic spasms at 10 months old. Serological testing for TORCH infections was negative. Conclusions: PSAT deficiency should be considered for patients with congenital microcephaly. Although further characterization of MRI findings in other patients is required, microencephaly with simplified gyral pattern could provide imaging clues for this rare metabolic disorder.

scholarly journals Biallelic Mutations in WDR12 is Associated With Male Infertility With Tapered-Head Sperm

2021 ◽  
Author(s):  
juan hua ◽  
Lan Guo ◽  
Yao Yao ◽  
Yangyang Wan ◽  
Wen Hu ◽  
...  
Keyword(s):  
Male Infertility ◽  
Molecular Mechanisms ◽  
Missense Variant ◽  
Bioinformatic Analysis ◽  
Chinese Family ◽  
Intense Staining ◽  
Whole Exome ◽  
Repeat Domain ◽  
Biallelic Mutations ◽  
Pachytene Spermatocytes

Abstract Teratozoospermia is a rare disease associated with male infertility. Unfortunately, approximately 30% of the genetic causes associated with teratozoospermia remain unknown. Several recurrent genetic mutations have been reported to be associated with globozoospermia, macrozoospermia and acephalic spermatozoa, whereas the genetic basis of tapered-head sperm is relatively less well-understood. In this study, whole-exome sequencing (WES) identified a homozygous WD repeat domain 12 (WDR12) (p.Ser162Ala/c.484T>G) variant in an infertile patient with tapered-head sperm from a consanguineous Chinese family. Bioinformatic analysis predicted this mutation to be a pathogenic variant. To further verify the effect of this variant, we analyzed WDR12 protein expression in the patient’s spermatozoa by western blot and found WDR12 to be significantly down-regulated. Also, we found that WDR12 expression is increased in pachytene spermatocytes, and intense staining was visible throughout the round spermatids in mouse testis. Based on our results, we concluded that a rare biallelic pathogenic missense variant (p.Ser162Ala/c.484T>G) in the WDR12 gene causes teratozoospermia. These results will provide novel insights into understanding the molecular mechanisms of male infertility and will help clinicians provide accurate diagnoses.

Perinatal Findings of Seckel Syndrome: A Case Report of a Fetus Showing Primordial Dwarfism and Severe Microcephaly

2008 ◽  
Vol 24 (4) ◽  
pp. 405-408 ◽  
Author(s):  
Keiko Miyachi Takikawa ◽  
Akihiko Kikuchi ◽  
Akiko Yokoyama ◽  
Kyoko Ono ◽  
Yuki Iwasawa ◽  
...  
Keyword(s):  
Case Report ◽  
Seckel Syndrome ◽  
Primordial Dwarfism

scholarly journals Biallelic mutations in M1AP are a frequent cause of meiotic arrest leading to male infertility

2019 ◽  
Author(s):  
Margot J. Wyrwoll ◽  
Şehime G. Temel ◽  
Liina Nagirnaja ◽  
Manon S. Oud ◽  
Alexandra M. Lopes ◽  
...  
Keyword(s):  
Male Infertility ◽  
Missense Variant ◽  
Severe Form ◽  
Obstructive Azoospermia ◽  
Loss Of Function ◽  
Meiotic Arrest ◽  
Infertile Men ◽  
Turkish Family ◽  
Cell Arrest ◽  
Biallelic Mutations

AbstractMale infertility affects ∼7% of men in Western societies, but its causes remain poorly understood. The most clinically severe form of male infertility is non-obstructive azoospermia (NOA), which is, in part, caused by an arrest at meiosis, but so far only few genes have been reported to cause germ cell arrest in males. To address this gap, whole exome sequencing was performed in 60 German men with complete meiotic arrest, and we identified in three unrelated men the same homozygous frameshift variant c.676dup (p.Trp226LeufsTer4) in M1AP, encoding meiosis 1 arresting protein. Then, with collaborators from the International Male Infertility Genomics Consortium (IMIGC), we screened a Dutch cohort comprising 99 infertile men and detected the same homozygous variant c.676dup in a man with hypospermatogenesis predominantly displaying meiotic arrest. We also identified two Portuguese men with NOA carrying likely biallelic loss-of-function (LoF) and missense variants in M1AP among men screened by the Genetics of Male Infertility Initiative (GEMINI). Moreover, we discovered a homozygous missense variant p.(Pro389Leu) in M1AP in a consanguineous Turkish family comprising five infertile men. M1AP is predominantly expressed in human and mouse spermatogonia up to secondary spermatocytes and previous studies have shown that knockout male mice are infertile due to meiotic arrest. Collectively, these findings demonstrate that both LoF and missense M1AP variants that impair its protein cause autosomal-recessive meiotic arrest, non-obstructive azoospermia and male infertility. In view of the evidence from several independent groups and populations, M1AP should be included in the growing list of validated NOA genes.

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