scholarly journals Neonatal presentation of familial glucocorticoid deficiency resulting from a novel splice mutation in the melanocortin 2 receptor accessory protein

2011 ◽  
Vol 165 (6) ◽  
pp. 987-991 ◽  
Author(s):  
V Jain ◽  
L A Metherell ◽  
A David ◽  
R Sharma ◽  
P K Sharma ◽  
...  
Keyword(s):  
Transmembrane Domain ◽  
Novel Mutation ◽  
Direct Sequencing ◽  
Autosomal Recessive Disorder ◽  
Normal Male ◽  
Accessory Protein ◽  
Homozygous Mutation ◽  
Early Presentation ◽  
Glucocorticoid Deficiency

BackgroundFamilial glucocorticoid deficiency (FGD) is a rare autosomal recessive disorder characterised by isolated glucocorticoid deficiency. Mutations in the ACTH receptor/melanocortin 2 receptor (MC2R), the MC2R accessory protein (MRAP) or the STAR protein (STAR) cause FGD types 1, 2 and 3, respectively, accounting for ∼50% of all cases.Patient and methodsWe report a neonate of Indian origin, who was diagnosed with FGD in the first few days of life. He presented with hypoglycaemic seizures and was noted to have generalised intense hyperpigmentation and normal male genitalia. Biochemical investigations revealed hypocortisolaemia (cortisol 0.223 μg/dl; NR 1–23 μg/dl) and elevated plasma ACTH (170 pg/ml). Serum electrolytes, aldosterone and plasma renin activity were normal. Peak cortisol following a standard synacthen test was 0.018 μg/dl. He responded to hydrocortisone treatment and continues on replacement. Patient DNA was analysed by direct sequencing. The effect of the novel mutation was assessed by an in vitro splicing assay using wild type and mutant heterologous minigenes.ResultsA novel homozygous mutation c.106+2_3dupTA was found in the MRAP gene. Both parents were heterozygous for the mutation. In an in vitro splicing assay, the mutation resulted in the skipping of exon 3.ConclusionWe have identified a novel MRAP mutation where disruption of the intron 3 splice-site results in a prematurely terminated translation product. This protein (if produced) would lack the transmembrane domain that is essential for MC2R interaction. We predict that this would cause complete lack of ACTH response thus explaining the early presentation in this case.

scholarly journals Novel Mutations in Thiazide-Sensitive Na-Cl Cotransporter Gene of Patients with Gitelman's Syndrome

2000 ◽  
Vol 11 (1) ◽  
pp. 65-70
Author(s):  
TOSHIAKI MONKAWA ◽  
ISAO KURIHARA ◽  
KAZUO KOBAYASHI ◽  
MATSUHIKO HAYASHI ◽  
TAKAO SARUTA
Keyword(s):  
Missense Mutation ◽  
Direct Sequencing ◽  
Gene Mutations ◽  
Autosomal Recessive Disorder ◽  
Japanese Patients ◽  
Paternal Allele ◽  
Homozygous Mutation ◽  
Gitelman's Syndrome ◽  
Sequencing Method

Abstract. Gitelman's syndrome (GS) is an autosomal recessive disorder characterized by metabolic alkalosis, hypokalemia, hypomagnesemia, and hypocalciuria that has recently been reported to be linked to thiazide-sensitive Na-Cl cotransporter (TSC) gene mutations. In this study, possible mutations in the TSC gene of six Japanese patients clinically diagnosed with GS were investigated. Twenty-six exons encoding TSC were amplified by PCR and then completely sequenced by the direct sequencing method. Patient A showed a missense mutation of Arg 642 to Cys on the paternal allele and a missense mutation of Val 578 to Met and a 2-bp deletion (nucleotide 2543-2544) on the maternal allele. This deletion results in a frameshift that alters codon 837 to encode a stop signal rather than phenylalanine, and it is predicted to lead to loss of the latter half of the intracellular carboxy terminus. In the second family, two affected sisters, patients B and C, had a homozygous missense mutation of Thr 180 to Lys. Both of their parents, who are consanguineously married, have a heterozygous Thr180Lys mutation. Patient D has a homozygous mutation Thr180Lys, which is the same as the second family. Haplotype analysis indicates that patients B and C are not related to patient D. In patients E and F, we could identify only one mutant allele; Ala569Glu and Leu849His, respectively. All of the mutations identified are novel except for the Arg642Cys mutation, which has been found in a Japanese GS patient. Although further in vitro study is required to prove that the mutations are responsible for GS, it is possible that Thr180Lys and Arg642Cys mutations might be common mutations in Japanese GS.

scholarly journals Localisation of the melanocortin-2-receptor and its accessory proteins in the developing and adult adrenal gland

2011 ◽  
Vol 46 (3) ◽  
pp. 227-232 ◽  
Author(s):  
Rebecca J Gorrigan ◽  
Leonardo Guasti ◽  
Peter King ◽  
Adrian J Clark ◽  
Li F Chan
Keyword(s):  
Adrenal Gland ◽  
Adrenal Cortex ◽  
Accessory Protein ◽  
Zona Fasciculata ◽  
Accessory Proteins ◽  
Similar Function ◽  
Glucocorticoid Deficiency ◽  
Inactivating Mutations

The melanocortin-2-receptor (MC2R)/MC2R accessory protein (MRAP) complex is critical to the production of glucocorticoids from the adrenal cortex. Inactivating mutations in either MC2R or MRAP result in the clinical condition familial glucocorticoid deficiency. The localisation of MC2R together with MRAP within the adrenal gland has not previously been reported. Furthermore, MRAP2, a paralogue of MRAP, has been shown in vitro to have a similar function to MRAP, facilitating MC2R trafficking and responsiveness to ACTH. Despite similar MC2R accessory functions, in vivo, patients with inactivating mutations of MRAP fail to be rescued by a functioning MRAP2 gene, suggesting differences in adrenal expression, localisation and/or function between the two MRAPs. In this study on the rat adrenal gland, we demonstrate that while MRAP and MC2R are highly expressed in the zona fasciculata, MRAP2 is expressed throughout the adrenal cortex in low quantities. In the developing adrenal gland, both MRAP and MRAP2 are equally well expressed. The MC2R/MRAP2 complex requires much higher concentrations of ACTH to activate compared with the MC2R/MRAP complex. Interestingly, expression of MC2R and MRAP in the undifferentiated zone would support the notion that ACTH may play an important role in adrenal cell differentiation and maintenance.

scholarly journals ACTH signalling and adrenal development: lessons from mouse models

2019 ◽  
Vol 8 (7) ◽  
pp. R122-R130 ◽  
Author(s):  
Tatiana V Novoselova ◽  
Peter J King ◽  
Leonardo Guasti ◽  
Louise A Metherell ◽  
Adrian J L Clark ◽  
...  
Keyword(s):  
Mouse Models ◽  
Transmembrane Domain ◽  
Accessory Protein ◽  
Beta Catenin ◽  
Shh Pathway ◽  
Acth Receptor ◽  
Glucocorticoid Deficiency ◽  
And Function ◽  
Cortisol Deficiency ◽  
Insight Into

The melanocortin-2-receptor (MC2R), also known as the ACTH receptor, is a critical component of the hypothalamic–pituitary–adrenal axis. The importance of MC2R in adrenal physiology is exemplified by the condition familial glucocorticoid deficiency (FGD), a potentially fatal disease characterised by isolated cortisol deficiency. MC2R mutations cause ~25% of cases. The discovery of a MC2R accessory protein MRAP, mutations of which account for ~20% of FGD, has provided insight into MC2R trafficking and signalling. MRAP is a single transmembrane domain accessory protein highly expressed in the adrenal gland and essential for MC2R expression and function. Mouse models helped elucidate the action of ACTH. The Mc2r-knockout (Mc2r − / − ) mice was the first mouse model developed to have adrenal insufficiency with deficiencies in glucocorticoid, mineralocorticoid and catecholamines. We recently reported the generation of the Mrap − / − mice which better mimics the human FGD phenotype with isolated glucocorticoid deficiency alone. The adrenal glands of adult Mrap − / − mice were grossly dysmorphic with a thickened capsule, deranged zonation and deranged WNT4/beta-catenin and sonic hedgehog (SHH) pathway signalling. Collectively, these mouse models of FGD highlight the importance of ACTH and MRAP in adrenal progenitor cell regulation, cortex maintenance and zonation.

scholarly journals Functional consequence of a novel Y129C mutation in a patient with two contradictory melanocortin-2-receptor mutations

2009 ◽  
Vol 160 (4) ◽  
pp. 705-710 ◽  
Author(s):  
Li F Chan ◽  
Teng-Teng Chung ◽  
Ahmed F Massoud ◽  
Louise A Metherell ◽  
Adrian J L Clark
Keyword(s):  
Cell Surface ◽  
Novel Mutation ◽  
Surface Expression ◽  
Cell Surface Expression ◽  
Missense Mutations ◽  
Intracellular Loop ◽  
Spastic Quadriplegia ◽  
Activating Mutation ◽  
Glucocorticoid Deficiency

ContextFamilial glucocorticoid deficiency (FGD) is a rare autosomal recessive disease, characterised by isolated glucocorticoid deficiency in the absence of mineralocorticoid deficiency. Inactivating mutations in the ACTH receptor (melanocortin-2-receptor, MC2R) are well described and account for ∼25% of cases. By contrast, activating MC2R mutations are extremely rare.PatientWe report a child of Saudi Arabian origin who was diagnosed with FGD following hypoglycaemic episodes that resulted in spastic quadriplegia.Methods and resultsMC2R gene analysis revealed an unusual combination of two homozygous missense mutations, consisting of the novel mutation Y129C and the previously described F278C activating mutation. Parents were heterozygous at both of these sites. In vitro analysis of the Y129C mutation using a fluorescent cell surface assay showed that this mutant was unable to reach the cell surface in CHO cells stably transfected with MC2R accessory protein (MRAP), despite the demonstration of an interaction with MRAP by co-immunoprecipitation. The double mutant Y129C-F278C also failed to traffic to the cell surface.ConclusionThe tyrosine residue at position 129 in the second intracellular loop is critical in MC2R folding and/or trafficking to the cell surface. Furthermore, the absence of cell surface expression of MC2R would account for the lack of activation of the receptor due to the F278C mutation located at the C-terminal tail. We provide a novel molecular explanation for a child with two opposing mutations causing severe FGD.

scholarly journals In Vitro Splicing Assay Proves the Pathogenicity of Intronic Variants in MRAP

2021 ◽  
Vol 5 (Supplement_1) ◽  
pp. A85-A86
Author(s):  
Chris Smith ◽  
Avinaash Vickram Maharaj ◽  
Younus Qamar ◽  
Jordan Read ◽  
Jack Williams ◽  
...  
Keyword(s):  
Splice Site ◽  
Early Onset ◽  
Neonatal Period ◽  
Donor Splice Site ◽  
Homozygous Mutation ◽  
Start Site ◽  
Donor Splice ◽  
In Vitro Splicing ◽  
Glucocorticoid Deficiency

Abstract Introduction: Familial glucocorticoid deficiency (FGD) is characterised by isolated glucocorticoid deficiency in a patient who retains normal mineralocorticoid production. FGD causing mutations in the MC2R accessory protein, MRAP, are often splice-site or nonsense mutations resulting in a truncated protein. Many of these mutations occur at the canonical donor splice-site of intron 3, where it has been shown previously that c.106 + 2_3dupTA, for example, results in skipping of the first coding exon with unknown consequences at the protein level. Patients and methods: DNA was isolated from three consanguineous individuals diagnosed with early onset FGD (0 - 13 months) with high ACTH and/or low cortisol levels and underwent whole exome sequencing. The proband in family 1 (P1) presented at 13 months and had a hyperpigmented sibling who died in neonatal period due to adrenal failure. Patient 2 (P2), who also had a family history of adrenal insufficiency, was noted to be hyperpigmented at birth with markedly raised ACTH, patient 3 (P3) was noted to have diffuse hyperpigmentation in the early neonatal period and on formal testing at 16m was found to have low serum cortisol. Variants were confirmed using Sanger sequencing and predicted splice-site mutations were investigated using an in vitro splicing assay. Results: Homozygous mutations in MRAP were identified in all three cases which were heterozygous in their parents. Previously described mutations, c.106 + 1delG (chr21:33671388delG; rs1476574441; CD050155) in P1 and c.106 + 2dupT (Chr21: 33671390_91insT; rs761576317; CI118288) in P2 at the canonical donor splice-site of intron 3, were identified, with the former predicted to destroy the splice site and the latter to weaken it. These mutations in vitro resulted in the complete skipping of exon 3, which contains the translational start site, and presumably result in no protein product. A novel homozygous mutation in intron 4, c.206 + 5G>T; (chr21:33679055G>T rs1064796398) was identified in P3, but was not predicted to alter splicing. In vitro, this mutation negates the canonical donor splice site and creates two different alternative sites, both resulting in frameshifts and predicted early termination of the protein (p.Val44fs*50, p.Pro72fs*90). Conclusion: All mutations reported here are predicted to produce no protein, either because the start site is excluded (for c.106 + 1delG and c.106 + 2dupT) or because the transcripts are likely to undergo nonsense mediated decay (for c.206 + 5G>T), resulting in the early onset FGD seen in the patients. Splice prediction protocols, although effective for variants within 2bp of exon/intron boundaries may not predict the true outcome of a base change whereas the splice assay conclusively revealed the effect of all three variants allowing us to assign pathogenicity to them.

scholarly journals Whole Exome Sequencing Identifies a Novel and a Recurrent Mutation inBBS2Gene in a Family with Bardet-Biedl Syndrome

2015 ◽  
Vol 2015 ◽  
pp. 1-5 ◽  
Author(s):  
Yong Mong Bee ◽  
Mayank Chawla ◽  
Yi Zhao
Keyword(s):  
Exome Sequencing ◽  
Whole Exome Sequencing ◽  
Novel Mutation ◽  
Direct Sequencing ◽  
Autosomal Recessive Disorder ◽  
The Novel ◽  
Nonsense Mutations ◽  
Bardet Biedl Syndrome ◽  
Next Generation Sequencing Technology ◽  
Whole Exome

Bardet-Biedl syndrome (BBS) is a rare autosomal recessive disorder known to be caused by mutations in at least 19 BBS genes. We report the genetic analysis of a patient with indisputable features of BBS including cardinal features such as postaxial polydactyly, retinitis pigmentosa, obesity, and kidney failure. Taking advantage of next-generation sequencing technology, we applied whole exome sequencing (WES) with Sanger direct sequencing to the proband and her unaffected mother. A pair of heterozygous nonsense mutations inBBS2gene was identified in the proband, one being novel and the other recurrent. The novel mutation, p.Y644X, resides in exon 16 and was also found in the heterozygous state in the mother. This mutation is not currently found in the dsSNP and 1000 Genome SNP databases and is predicted to be disease causing byin silicoanalysis. This study highlights the potential for a rapid and precise detection of disease causing gene using WES in genetically heterogeneous disorders such as BBS.

Pulmonary hemorrhage in a case of CD25 deficiency

2014 ◽  
Vol 01 (01) ◽  
pp. 39-43 ◽  
Author(s):  
Nashat Al Sukaiti ◽  
Aisha Al Sinani ◽  
Suad Al Ismaily ◽  
Samiuddin Shaikh ◽  
Safia Al Abrawi
Keyword(s):  
Novel Mutation ◽  
Pulmonary Hemorrhage ◽  
Insulin Dependent Diabetes Mellitus ◽  
Dependent Diabetes Mellitus ◽  
Homozygous Mutation ◽  
Early Presentation ◽  
Insulin Dependent ◽  
Autoimmune Cytopenia ◽  
Lymphocyte Phenotyping

Introduction: Presentation with severe autoimmune manifestations in early infancy is rare, especially when the gut is not involved. Methods: Lymphocyte phenotyping, determination of autoantibodies, and Sanger sequencing were employed to investigate this case. Results: A novel homozygous mutation in CD25 was identified in the patient who presented in the first weeks of life with insulin-dependent diabetes mellitus (IDDM) and subsequently developed autoimmune cytopenia and pulmonary hemorrhage. Conclusion: CD25 deficiency is present in the Gulf (Oman) and cases with early autoimmune manifestations should be tested for this possibility. Statement of novelty: A novel mutation in CD25 leads to an early presentation of IDDM and pulmonary hemorrhage.

scholarly journals Mitochondrial Neurogastrointestinal Encephalomyopathy Disease in Three Siblings from Pakistan with a Novel Mutation

2018 ◽  
Vol 08 (01) ◽  
pp. 015-019
Author(s):  
Sana Durrani ◽  
Bee Chen ◽  
Yusnita Yakob ◽  
Lua Hian ◽  
Bushra Afroze
Keyword(s):  
Thymidine Phosphorylase ◽  
Autosomal Recessive ◽  
Novel Mutation ◽  
Gastrointestinal Symptoms ◽  
Autosomal Recessive Disorder ◽  
Homozygous Mutation ◽  
Pakistani Family ◽  
Mitochondrial Neurogastrointestinal Encephalomyopathy ◽  
Intestinal Dysmotility ◽  
Sensorineural Hearing Impairment

AbstractMitochondrial neurogastrointestinal encephalomyopathy (MNGIE) is a rare multisystem autosomal recessive disorder. The disease is clinically heterogeneous with gastrointestinal symptoms of intestinal dysmotility and cachexia as well as neurological symptoms of ophthalmoplegia, neuropathy, sensorineural hearing impairment, and diffuse leukoencephalopathy being most prominent. MNGIE is caused by mutations in TYMP, a gene that encodes thymidine phosphorylase (TP)—a cytosolic enzyme. Mutations in TYMP lead to very low TP catalytic activity, resulting in dramatically increased thymidine and deoxyuridine in plasma. We describe the clinical, biochemical, and neuroimaging findings of three boys with MNGIE from a Pakistani family with a novel homozygous mutation, c.798_801dupCGCG p. (Ala268Argfs*?), in exon 7 of TYMP.

A novel ALMS1 homozygous mutation in two Turkish brothers with Alström syndrome

2016 ◽  
Vol 29 (5) ◽  
Author(s):  
Caley Laxer ◽  
Sofia A. Rahman ◽  
Maha Sherif ◽  
Sophia Tahir ◽  
Atilla Cayir ◽  
...  
Keyword(s):  
Autosomal Recessive ◽  
Novel Mutation ◽  
Autosomal Recessive Disorder ◽  
Homozygous Mutation ◽  
Consanguineous Family ◽  
Complex Phenotype ◽  
Rare Autosomal Recessive Disorder ◽  
Alström Syndrome ◽  
Alstrom Syndrome

AbstractAlström syndrome (AS) is an extremely rare, autosomal recessive disorder characterised by multi-organ features that typically manifest within the first two decades of life. AS is caused by mutations in the Alström syndrome 1 (In the current study, two brothers from a first-cousin consanguineous family presented with a complex phenotype and were suspected of having AS.Both brothers were found to be homozygous for a novel nonsense c.7310C>A (p.S2437X) mutation in exon-8 ofThis particular mutation has never been reported before and confirmed the diagnosis of AS in the patients. Our work identifies a novel mutation in

A Novel Mutation Glyl672→Arg in Type 2A and a Homozygous Mutation in Type 2B von Willebrand Disease

1996 ◽  
Vol 76 (02) ◽  
pp. 253-257 ◽  
Author(s):  
Takeshi Hagiwara ◽  
Hiroshi Inaba ◽  
Shinichi Yoshida ◽  
Keiko Nagaizumi ◽  
Morio Arai ◽  
...  
Keyword(s):  
Missense Mutation ◽  
Novel Mutation ◽  
Point Mutations ◽  
Japanese Patients ◽  
Von Willebrand Disease ◽  
Homozygous Mutation ◽  
Missense Mutations ◽  
Reaction Products ◽  
Type 3 ◽  
Von Willebrand

SummaryGenetic materials from 16 unrelated Japanese patients with von Willebrand disease (vWD) were analyzed for mutations. Exon 28 of the von Willebrand factor (vWF) gene, where point mutations have been found most frequent, was screened by various restriction-enzyme analyses. Six patients were observed to have abnormal restriction patterns. By sequence analyses of the polymerase chain-reaction products, we identified a homozygous R1308C missense mutation in a patient with type 2B vWD; R1597W, R1597Q, G1609R and G1672R missense mutations in five patients with type 2A; and a G1659ter nonsense mutation in a patient with type 3 vWD. The G1672R was a novel missense mutation of the carboxyl-terminal end of the A2 domain. In addition, we detected an A/C polymorphism at nucleotide 4915 with HaeIII. There was no particular linkage disequilibrium of the A/C polymorphism, either with the G/A polymorphism at nucleotide 4391 detected with Hphl or with the C/T at 4891 detected with BstEll.

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