Treatment with lactose (galactose)-restricted and medium-chain triglyceride-supplemented formula for neonatal intrahepatic cholestasis caused by citrin deficiency.

Citrin plays a role in the transfer of NADH-reducing equivalent from cytosol to mitochondria as part of the malate-aspartate shuttle in liver. Citrin deficiency may cause an impairment of glycolysis due to an increase in the cytosolic NADH/NAD ratio leading to an energy shortage in the liver. Mutations of the SLC25A13 gene are responsible for neonatal intrahepatic cholestasis (NICCD) and adult-onset type II citrullinemia (CTLN2). Most patients with NICCD show a resolution of symptoms within the first year of life, but some patients present with severe symptoms and require liver transplantation. We treated four patients including three siblings with NICCD by lactose (galactose)-restricted and medium-chain triglyceride (MCT)-supplemented formula. This formula rapidly improved the clinical condition and laboratory findings. Early treatment was more effective and did not require long-term administration. Lactose (galactose)-restriction can avoid further increase in the cytosolic NADH/NAD ratio in the liver and MCT supplementation can provide energy to hepatic cells by producing an excess of acetyl-CoA in mitochondria. Early treatment with lactose (galactose)-restricted and MCT-supplemented formula is recommended for patients with NICCD and possibly for patients with CTLN2.

Charcot-Marie-Tooth families in Japan with MPZ Thr124Met mutation.

BACKGROUND: The MPZ Thr124Met mutation is characterised by a late onset, pupillary abnormality, deafness, normal or moderate decreased motor nerve conduction velocity, and axonal damage in sural nerve biopsy. OBJECTIVE: To investigate the clinical manifestations of the axonal or demyelinating forms of the Japanese MPZ Thr124Met mutation originating in four different areas: Tottori, Nara, Aichi, and Ibaragi. RESULTS: Genotyping with DNA microsatellite markers linked to the MPZ gene on chromosome 1q22-q23 showed shared allelic characteristics between 12.65 cM and revealed a common haplotype in all Tottori families. Aichi and Ibaragi families shared parts of the haplotype around the MPZ gene. However, there was no consistency with a Nara family. CONCLUSIONS: The high frequency of this peculiar genotype in the Tottori CMT population is presumably due to a founder effect, but in Thr124 it might constitute a mutation hotspot in the MPZ gene.

Two cases of mosaic RhD blood-group phenotypes and paternal isodisomy for chromosome 1.

We encountered a 22-year-old man (case 1) and a 23-year-old woman (case 2), both unrelated and healthy. They were mosaic for the Rh blood group phenotype: one erythrocyte population was D-positive and the other was D-negative. Flow cytometric analysis of density profile of RhD antigen in their erythrocytes, and cytogenetic analysis including in situ hybridization using an RHD/RHCE-containing PAC clone, excluded a deletion of the RHD/RHCE gene complex, but suggested the presence of cells with uniparental disomy for chromosome 1 (UPD1). Microsatellite marker analysis was performed in both probands and their family members. In case 1, the analysis with markers spanning the chromosome 1 revealed both maternal and paternal alleles in his peripheral blood leukocytes (PBL), Epstein-Barr virus-transformed lymphoblastoid cells (EBL), and buccal mucosal cells. However, only paternal alleles were detected in all of 50 individual pieces of his hair or hair-roots and all of five monoclonal cell lines cloned from his established EBL. There was no direct evidence of heterozygous, biparental alleles in these two tissues. The presence of maternal isodisomy 1 was not absolutely ruled out in other tissues examined in case 1. Similar results were obtained in case 2, showing biparental, disomic patterns in her PBL and in 15 of 20 pieces of her hair roots, and showing monoallelic patterns in the remaining five pieces of hair roots. Analysis with markers for other autosomes confirmed their biparental inheritance. These findings indicated that both cases had at least two cell populations, one population having paternal UPD1 (isodisomy 1), and another heterozygous, biparental disomy 1. We emphasize that isodisomy for chromosome 1 is not infrequent and may cause unusual RhD phenotype, as seen in cases we described.

Mutation of the doublecortin gene in male patients with double cortex syndrome: somatic mosaicism detected by hair root analysis.

The molecular basis of double cortex syndrome was investigated in 2 male patients. Magnetic resonance imaging of the patients' heads showed diffuse subcortical band heterotopia, as is seen in female patients. We found a heterozygous mutation for Asp50Lys or Arg39Stop in both patients. Microsatellite polymorphism analysis revealed that both patients had inherited a single X chromosome from their mothers. Restriction enzyme analysis using DNA extracted from the hair roots of each patient showed four different patterns in the combination of cells carrying wild and mutant alleles, which strongly suggest somatic mosaicism. We conclude that somatic mosaic mutations in the doublecortin gene in male patients can cause subcortical band heterotopia, and that molecular analysis using hair roots is a useful method for detecting somatic mosaicism.

Hemizygous mutation of the peripheral myelin protein 22 gene associated with Charcot-Marie-Tooth disease type 1.

We studied a female patient who presented with autosomal recessive or sporadic Charcot-Marie-Tooth disease type 1 (CMT1). We found that she had a 1.5-megabase deletion in chromosome 17p11.2-p12 containing the peripheral myelin protein 22 gene (PMP22) and an Arg157Gly mutation of PMP22. Hemizygous mutation of PMP22 should be considered in patients with autosomal recessive CMT1 or with severe hereditary neuropathy with liability to pressure palsy.

Deletion and nonsense mutations of the connexin 32 gene associated with Charcot-Marie-Tooth disease.

Two patients with a mild to moderate phenotype of Charcot-Marie-Tooth disease were identified to carry the mutations of the connexin (Cx) 32 gene. One of the patient had a novel nonsense mutation of tryptophan at amino acid 132 and the other had a deletion of the Cx 32 gene. Our study indicated that a loss of Cx 32 function contributes to a major pathogenesis of X-linked Charcot-Marie-Tooth disease.

Muscular dystrophy associated with extra-abdominal desmoid tumor showing aberrant chromosome 1 [46,XX,add(1)(p36)].

We report on a 2-year-old girl with probable limb-girdle muscular dystrophy associated with an extra-abdominal desmoid tumor of the right mandible. This association is previously undescribed. The tumor was totally removed. Cytogenetic analysis of the tumor showed a clonal karyotypic abnormality: 46,XX,add(1)(p36) in 3 of 20 cells analyzed. Since an association of a neoplasm with limb-girdle muscular dystrophy has previously been reported in 3 cases, the two abnormalities are likely related causally. The chromosome abnormality in our patient may play a role in the occurrence of her desmoid tumor.