Masashi Kondo

Patients Homozygous for the T435N Mutation of Succinyl-CoA:3-Ketoacid CoA Transferase (SCOT) Do Not Show Permanent Ketosis

Succinyl-CoA:3-ketoacid CoA transferase (SCOT; locus symbol OXCT; E.C. 2.8.3.5) is the main determinant of the ketolytic capacity of tissues. Hereditary SCOT deficiency causes episodic ketoacidosis. Permanent ketosis has been regarded as a pathognomonic feature of SCOT deficiency. There are three SCOT-deficient patients from a small region in Japan and they have not manifested permanent ketosis, even though their ketoacidotic crises were as severe as those of other SCOT-deficient patients. All three were homozygous for the T435N mutation. Transient expression analysis of wild-type and mutant cDNA showed that the T435N mutant retained significant residual SCOT activities (20% for that of the wild-type at 39.5°C, 25% at 37°C, and 50% at 30°C). The difference of residual SCOT activities at these temperatures in expression analyses was due to differences in the level of the mutant protein. SCOT activity of the T435N protein was more vulnerable than the wild-type to heat treatment at 42°C and 55°C. These temperature-sensitive characteristics of the mutant protein may explain, in part, why the patients developed ketoacidotic crises during febrile illness. In SCOT-deficient patients retaining some residual activity, permanent ketosis may be absent.

Mitochondrial acetoacetyl-CoA thiolase (T2) deficiency: T2-deficient patients with "mild" mutation(s) were previously misinterpreted as normal by the coupled assay with tiglyl-CoA.

Mitochondrial acetoacetyl-CoA thiolase (T2) deficiency is an inborn error of metabolism that affects the catabolism of isoleucine and ketone bodies. This disorder is characterized by intermittent ketoacidotic episodes. Recently, we diagnosed T2 deficiency in two patients (GK45 and GK47) by the absence of potassium ion-activated acetoacetyl-CoA thiolase activity, whereas these patients were previously misinterpreted as normal by a coupled assay with tiglyl-CoA as a substrate. This method has been widely used for the enzymatic diagnosis of the T2 deficiency in the United States and Europe. We hypothesized that some residual T2 activity showed normal results in the assay. To prove this hypothesis, we analyzed these two patients together with three typical T2-deficient patients (GK46, GK49, and GK50) at the DNA level. Expression analysis of mutant cDNAs clearly showed that GK45 and GK47 had “mild” mutations (A132G, D339-V340insD) that retained some residual T2 activity, at least one of two mutant alleles, whereas the other three patients had null mutations (c.52–53insC, G152A, H397D, and IVS8+1g>t) in either allele. These results raise the possibility that T2-deficient patients with mild mutations have been misinterpreted as normal by the coupled assay with tiglyl-CoA.

Leaky phenotype of X-linked agammaglobulinaemia in a Japanese family

X‐linked agammaglobulinaemia (XLA) is an inherited immunodeficiency that is caused by a block in early B‐cell differentiation. Whereas early B precursors in the bone marrow are present in substantial numbers, XLA‐affected individuals have dramatically reduced numbers of circulating mature B cells, plasma cells and immunoglobulins of all isotypes. We report on a Japanese family with 3 XLA patients, in whom the serum immunoglobulin levels and number of B cells showed a significant difference among them in spite of harbouring the same splice donor site mutation in the BTK gene. We developed concise method for detection of this mutation, which is helpful for discovering the carrier. Patient 2 showed a significant serum immunoglobulin levels of all isotypes, including allergen‐specific IgE. Expression of a normal and truncated size BTK gene was detected in patient 2′s peripheral blood mononuclear cells (PBMCs). Expression of BTK protein was also detected in some B cells. These results suggest that the leaky phenotype in patient 2 was caused in part by the expression of a normal BTK gene transcript. The increased frequency of infection with age expanded the number of B cells with normal BTK gene expression and produced the serum immunoglobulin, including IgE.

The response of bovine beta-lactoglobulin-specific T-cell clones to single amino acid substitution of T-cell core epitope

Cow’s milk is one of the most common food allergens in the first year of life, with approximately 2.5% of infants experiencing an allergic reaction to it. Beta‐lactoglobulin (BLG) is one of the major allergens in cow’s milk. Previously, we reported that four of six T‐cell clones (TCC) which were established from cow’s milk allergy patients recognized BLGp97‐117 as the core sequence and also recognized BLG in association with the human leucocyte antigen (HLA)‐DRB1*0405 allele. Using two of these four TCCs, we evaluated the T‐cell response to BLG peptides with single amino acid substitution or deletion and identified BLGp102‐112 as the minimum essential region in BLGp97‐117. In the alanine‐scan assay, the proliferative responses of TCCs to pE108A disappeared, and the proliferative responses of TCCs to pC106A decreased. In the analog peptide proliferation assay, pY102S had retained some T‐cell response to the two TCCs. Collecting these results, we propose a motif for the interaction between the HLA‐DRB1*0405 allele and antigen peptide, and suggest that BLGp105‐108 are important residues to retain the TCR/BLG‐peptide/HLA complex. pY102A and pY102S are partial agonists for the T‐cell receptor. These peptides might be considered as candidate peptides for the modification of the T‐cell response to BLG in cow’s milk allergy.

Total IgE at 6 months predicts remittance or persistence of atopic dermatitis at 14 months.

Some patients with infantile atopic dermatitis (AD) achieve remission around 1 year old, but in others it persists. The difference between them is unclear. We performed a birth cohort study to find the markers predicting the outcome of infantile AD. We followed up a cohort (n = 314) from birth to 14 months of age, and cord blood was taken from the participants. Some of them (n = 144) had a physical examination and a blood test at 6 and 14 months of age. The subjects who had AD at 6 months (n = 34) were divided into two groups, named the transient group (those who had no AD at 14 months of age; n = 16) and the persistent group (those who still had AD at 14 months of age; n = 18). Then, laboratory data were compared between these two groups. Percentage of CD8 in cord blood lymphocytes and total IgE at 6 months of age in the persistent group was significantly higher than those of the transient group. The area under the curves of a receiver operating characteristic analysis were 0.792 (p = 0.007) and 0.722 (p = 0.027). In the persistent group, total IgE, percentages of T-helper (Th) 2 and phytohemagglutinin-induced IL-4 production from peripheral blood mononuclear cells at 14 months of age were also significantly higher than those of the transient group. Thus Th2 polarization in the persistent group was confirmed. In clinical use, total IgE at 6 months of age is the most useful predictive marker to know the outcome of infantile AD. The clinical trial registration ID is UMIN000002926.

A common variable immunodeficient patient who developed acute disseminated encephalomyelitis followed by the Lennox-Gastaut syndrome.

Common variable immunodeficiency (CVID) is a primary disorder characterized by impaired antibody production. CVID patients may develop recurrent infections, autoimmune disorders, and malignant lymphomas, but to our knowledge, there is no report on CVID patients who develop acute disseminated encephalomyelitis (ADEM) or the Lennox‐Gastaut syndrome. We describe a 1‐yr‐old female CVID patient with ADEM who evolutionally manifested the Lennox‐Gastaut syndrome. She was admitted with convulsions and T2‐weighted magnetic resonance imaging (MRI) revealed high‐intensity areas in the right temporal lobe and the left fronto‐parietal region but she became conscious soon. Her serum findings showed severe hypogammaglobulinemia and a follow up MRI revealed that these areas had diminished. Consequently, she was diagnosed as having CVID with ADEM. After 5 months, she fell to having tonic and absence seizures and we diagnosed her as having the Lennox‐Gastaut syndrome from electroencephalograms (EEG) and the seizure pattern. She is now 7 yr old and her tonic seizures are controlled with valproic acid, clobazam, and immunoglobulin replacement therapy which is administrated every 2 wk. It is well known that the immune and neurologic systems have a close relationship. We suspect that a genetic defect in the immune system of our patient might also be associated with the neurologic disorders of ADEM and the Lennox‐Gastaut syndrome.

Lymphocyte Responses to Chymotrypsin- or Trypsin V-Digested β-Lactoglobulin in Patients with Cow's Milk Allergy

Chymotrypsin- or trypsin V- (a mixture of trypsin and chymotrypsin) digested β-lactoglobulin (BLG) peptides were prepared and were confirmed to have much less immunoglobulin (lg)G and lgE reactivity compared with intact BLG by IgG inhibition enzymelinked immunosorbent assay and IgE dot blotting. The lymphocyte responses to intact BLG and these peptides were examined using peripheral blood mononuclear cells (PBMCs) from 10 patients with cows milk allergy. The PBMCs from most patients had lower lymphocyte responses to chymotrypsin- and trypsin V-digested BLG peptides than those to intact BLG. However, PBMCs from one and two patients retained significant proliferative responses to both peptides and to only the former peptide, respectively. Interferon-c production stimulated by chymotrypsin-digested peptides was still detectable in all five patients tested. Chymotrypsindigested BLG reduced lgE reactivity but still induced some lymphocyte responses.

Autologous peripheral blood stem cell transplantation in a patient with relapsed pleuropulmonary blastoma.

Pleuropulmonary blastoma (PPB) is a rare and aggressive primary intrathoracic neoplasma of children. The prognosis is extremely poor with frequent metastasis to the brain and bone. We present a 4-year-old girl with a tumor mass in the right hemithorax initially diagnosed as pneumoniae. Tumor resection was performed and the histologic report indicated the diagnosis of PPB. The patient received chemotherapy comprising vincristine, actinomycin D, doxorubicin, cisplatin, and cyclophosphamide. Irradiation was performed with total 45 Gy at the right lower pulmonary lobe. She relapsed 29 months later at the pleura between the right middle and lower pulmonary lobe. Tumor resection and total 45 Gy of irradiation were performed again. High-dose chemotherapy comprising cisplatin, adriamycin, and cyclophosphamide was performed followed by autologous peripheral blood stem cell transplantation (PBSCT). The patient achieved complete hematologic recovery. Thirty-one months after PBSCT, no signs of relapse have been observed. Although it might be that the patient could have been cured with second surgery alone or by the surgery and subsequent chemotherapy, high-dose chemotherapy and PBSCT should be considered for the treatment of relapsed PPB.

Comparison of mitochondrial A3243G mutation loads in easily accessible samples from a family with maternally inherited diabetes and deafness.

The mitochondrial A3243G mutation is most commonly related to the MELAS syndrome, but can cause many different clinical manifestations at various ages. Here, we present a family with maternally inherited diabetes and deafness (MIDD), the proband of which exhibits hearing loss, diabetes mellitus, cardiomyopathy and short stature. Four easily accessible samples (whole blood, hair roots, buccal scrapings and urinary sediment) from the proband and her 3 sons were simultaneously analyzed for heteroplasmic percentages of the A3243G mutation in their DNA. More than 10 subclones were sequenced and the percentage of clones possessing the A3243G mutation was calculated. The proportion of mutant genomes varied widely among the four samples tested. Blood DNA consistently had the lowest percentage of mutation load, while urinary sediment tended to have the highest. The 3 sons have not exhibited hearing disability or diabetes mellitus thus far. However, their mutation loads in all 4 tissue samples were higher than those in the corresponding samples from the proband. Follow-up of this family over time is necessary to understand the relationship between the heteroplasmic mutation loads in the 4 different samples and the clinical manifestations of MIDD/MELAS.