Glycine N-methyltransferase deficiency: a novel inborn error causing persistent isolated hypermethioninaemia

This paper reports clinical and metabolic studies of two Italian siblings with a novel form of persistent isolated hypermethioninaemia, i.e. abnormally elevated plasma methionine that lasted beyond the first months of life and is not due to cystathionine -synthase deficiency, tyrosinaemia I or liver disease. Abnormal elevations of their plasma S-adenosylmethionine (AdoMet) concentrations proved they do not have deficient activity of methionine adenosyltransferase I/III. A variety of studies provided evidence that the elevations of methionine and AdoMet are not caused by defects in the methionine transamination pathway, deficient activity of methionine adenosyltransferase II, a mutation in methylenetetrahydrofolate reductase rendering this activity resistant to inhibition by AdoMet, or deficient activity of guanidinoacetate methyltransferase. Plasma sarcosine (N-methylglycine) is elevated, together with elevated plasma AdoMet in normal subjects following oral methionine loads and in association with increased plasma levels of both methionine and AdoMet in cystathionine -synthase-deficient individuals. However, plasma sarcosine is not elevated in these siblings. The latter result provides evidence they are deficient in activity of glycine N-methyltransferase (GNMT). The only clinical abnormalities in these siblings are mild hepatomegaly and chronic elevation of serum transaminases not attributable to conventional causes of liver disease. A possible causative connection between GNMT deficiency and these hepatitis-like manifestations is discussed. Further studies are required to evaluate whether dietary methionine restriction will be useful in this situation.     

A novel factor XI gene mutation associated with mild factor XI deficiency in a symptomatic patient.

Congenital factor XI deficiency is a rare condition, in which plasma factor XI levels correlate poorly with the severity of haemorrhage. The condition is typically characterized by post-traumatic bleeding. The factor XI gene is located on chromosome 4 and contains 15 exons. More than 80 mutations have so far been described. We describe a novel mutation in the factor XI gene associated with mild factor XI deficiency. The patient, who is of Irish descent, has a history of post-traumatic bleeding and was found to have a borderline factor XI deficiency. DNA sequence analysis of the factor XI gene revealed a novel T to A mutation at nucleotide 168 resulting in the substitution of the cysteine residue at codon 38 with a stop codon (Cys38STOP). The mutation predicts the premature termination of translation of factor XI mRNA resulting in a truncated, and probably unstable, factor XI protein. The presence of the mutation is consistent with the patient's borderline factor XI deficiency.     

A novel mutation in a Turkish patient with Hermansky-Pudlak syndrome type 5

The Hermansky-Pudlak syndrome (HPS) is a rare genetically heterogeneous autosomal recessive disorder, characterized by tyrosinase-positive oculocutaneous albinism, platelet dysfunction and lysosomal ceroid lipofuscin storage. This is caused by defects in lysosome-related organelles. In humans eight different types of the syndrome are known, of which a short overview is given. The clinical features and a novel mutation of a patient with HPS type 5 are described here.     

A novel mutation in a patient with familial renal hypouricemia type 2

IntroductionHypouricemia may be caused by disorders leading to decreased UA production, oxidation of UA to allantoin by drugs or increased renal tubular loss of filtered UA, renal hypouricemia (RHUC). RHUC may be resulted from familial or acquired disorders. Familial RHUC cases are classified according to the gene affected as type 1 (SLC22A12 gene) and type 2 (SLC2A9). Clinical importance of RHUC entity is mainly determined by emerging of acute kidney injury (AKI) after strenuous exercise and urolithiasis.Case presentationHere, we report a case of RHUC with increased fractional excretion of uric acid value of more than 100%, serum uric acid level of nearly zero, and exercise-induced AKI episodes clinically and a new unpublished homozygous (biallelic) mutation of c.1419+2T>G (IVS11+2T>G) in the SLC2A9 gene genetically for the first time to our knowledge.ConclusionClinicians should be aware of this rare entity defined as hereditary RHUC in order to provide long term renoprotection by advisements like simple precautions such as avoiding severe exercises.     

A spontaneous novel XK gene mutation in a patient with McLeod syndrome

A 29-year-old man with a history of elevated creatine kinase and necrotizing myopathy was reviewed. Prominent red cell acanthocytosis in association with reduced Kell antigen expression was present, findings consistent with the McLeod syndrome. Investigation of the patient's XK gene revealed a novel TGG- to-TAG transition at position 1023 in exon 3. This point mutation creates an in-frame stop codon (W314X), and predicts a truncated XK protein of 313 amino acids, compared with 444 amino acids in the normal XK protein. The mutation was not identified in the patient's mother or sister indicating that this mutation was spontaneous.     

Homozygous protein C deficiency with purpura fulminans: report of a new case and a description of a novel mutation.

We report here a quite rare case of severe homozygous protein C deficiency. The index case is a 9-month-old Saudi boy who was born after an uneventful pregnancy at 39 weeks. The diagnosis of epidermoloysis bullosa and the appearance of scrotal haematoma raised the diagnosis of thrombosis due to protein C deficiency. The clinical presentation and extremely low level of protein C activity (< 0.01 U/ml) in the index case suggested a severe case of protein C deficiency. The father is 28 years old and the mother is 25 years old and are consanguineous. Neither had a personal or family history of thrombosis. Genomic DNA was extracted from peripheral blood of the patient and both parents, exons of protein C were amplified by polymerase chain reaction and sequenced. Sequencing revealed the presence of a novel CCTG duplicate nucleotide (effective insertion) after nucleotide 8826 in exon 9 of the protein C gene. This insertion is found in the homozygous state in the patient and in the heterozygous state in both parents. It results in a frame-shift mutation, which introduces a stop-codon, thereby generating a prematurely truncated protein. These molecular findings agree with the presence of quantitative protein C deficiency in the index case.     

A novel missense mutation causing abnormal LMAN1 in a Japanese patient with combined deficiency of factor V and factor VIII

Combined deficiency of coagulation factor V (FV) and factor VIII (FVIII) (F5F8D) is an inherited bleeding disorder characterized by a reduction in plasma concentrations of FV and FVIII. F5F8D is genetically linked to mutations in either LMAN1 or MCFD2. Here, we investigated the molecular basis of F5F8D in a Japanese patient, and identified a novel missense mutation (p.Trp67Ser, c.200G>C) in the LMAN1, but no mutation in the MCFD2. The amount of LMAN1 in Epstein‐Barr virus‐immortalized lymphoblasts from the patient was found to be almost the same as that in cells from a normal individual. Interestingly, an anti‐MCFD2 antibody did not co‐immunoprecipitate the mutant LMAN1 with MCFD2 in lymphoblasts from the patient, suggesting the affinity of MCFD2 for the mutant LMAN1 is weak or abolished by the binding of the anti‐MCFD2 antibody. In addition, a Myc/6×His‐tagged recombinant form of wild‐type LMAN1 could bind to D‐mannose, but that of the mutant could not. The p.Trp67Ser mutation was located in the carbohydrate recognition domain (CRD), which is thought to participate in the selective binding of LMAN1 to the D‐mannose of glycoproteins as well as the EF‐motif of MCFD2. Taken together, it was suggested that the p.Trp67Ser mutation might affect the molecular chaperone function of LMAN1, impairing affinity for D‐mannose as well as for MCFD2, which may be responsible for F5F8D in the patient. This is the first report of F5F8D caused by a qualitative defect of LMAN1 due to a missense mutation in LMAN1. Am. J. Hematol. 2009. © 2009 Wiley‐Liss, Inc.     

Unusual presentation of familial glucocorticoid deficiency with a novel MRAP mutation

CONTEXT: Mutations in MRAP, an interacting partner of the ACTH receptor, have been shown recently to cause familial glucocorticoid deficiency (FGD) in kindreds with confirmed FGD and no ACTH receptor mutations. OBJECTIVE: We describe a Jewish-Ethiopian family with FGD caused by a novel MRAP mutation. PATIENTS: Our index patient presented at the age of 19 months with hypocortisolism, severe psychomotor retardation, myoclonic seizures, spastic quadriparesis, and microcephaly. Before the definite diagnosis was made, a female sibling was born in another hospital and succumbed during the neonatal period due to sepsis and adrenal crisis. METHODS: DNA was extracted from peripheral blood samples from the index case and his mother and from fibroblasts obtained from the female patient. The DAX-1, ACTH receptor (MC2R), and MRAP genes were analyzed. RESULTS: The index patient was diagnosed with FGD and was found to be homozygous for a novel MRAP mutation, a seven-base deletion in exon 3 of the MRAP gene. This deletion causes a frame shift, resulting in a stop codon after 23 amino acids (L31X). Postmortem analysis of fibroblasts obtained from the female patient revealed that she harbored the same mutation. CONCLUSIONS: This is the first report of MRAP mutations after the recent identification of the gene. Whether the novel MRAP mutation described by us is associated with a particularly severe phenotype remains to be investigated.     

Glycine N-methyltransferase is a favorable prognostic marker for human cholangiocarcinoma

Background and Aim:  Glycine N -methyltransferase (GNMT) is a susceptibility gene for human hepatocellular carcinoma (HCC). We previously reported that GNMT expression is diminished in HCC. Here we report our examination of GNMT expression patterns in cholangiocarcinoma and the relationship between its expression and prognosis.
Methods:  We analyzed GNMT expression in tumor tissues from 33 cholangiocarcinoma patients (19 male) using immunohistochemistry (IHC) procedures with a GNMT monoclonal antibody (mAb 4–17). GNMT expression intensity and percentages were scored on a scale of 0 to 6. The association between GNMT expression and survival was analyzed using the Kaplan–Meier method, and prognostic factors were evaluated with a multivariate Cox proportional hazards regression model.
Results:  High GNMT expression was found in epithelial cells of normal bile ducts. Six of 33 (18.2%) cholangiocarcinoma tissues had no GNMT expression. A statistically significant difference was noted in GNMT expression between male and female patients (68.4% vs 100%, P  < 0.05). Compared to patients with GNMT expression scores > 3, the death hazard ratio for patients with GNMT scores ≤ 3 was 3.68 (95% confidence interval = 1.17–11.59, P  < 0.05).
Conclusions:  GNMT expression is a favorable prognosis predictor for cholangiocarcinoma.     

Iron chelation therapy in aceruloplasminaemia: study of a patient with a novel missense mutation

We describe a novel missense mutation of ceruloplasmin in a patient with aceruloplasminaemia causing the replacement of a neutral amino acid (phenylalanine) with a polar one (serine) at position 198, probably leading to abnormal folding and secretion of the protein. The patient showed mild microcytic anaemia, mild hepatic iron overload, and marked brain iron overload. Six months of therapy with deferiprone was ineffective in removing iron from the tissues. Deferoxamine was more efficient in removing excess iron from the liver but aggravated the disease related anaemia. After more than one year of chelation treatment, the brain magnetic resonance imaging signal did not change. Overall, these findings indicate that treatment of iron overload in aceruloplasminaemia is a difficult challenge and that new iron chelators, more efficient in crossing the blood-brain barrier, are needed.