Basan syndrome in a family from South India: a novel SMARCAD1 variant

Basan syndrome is a rare ectodermal dysplasia characterized by a triad of adermatoglyphia, reticulate pigmentation and nail dystrophy, in addition to transient neonatal findings of acral blistering and facial milia. The genetic basis was recently established to be heterozygous mutations affecting the skin-specific isoform of SMARCAD1. It is now considered part of the spectrum of disorders resulting from haploinsufficiency of this isoform, which includes both Huriez syndrome and autosomal dominant adermatoglyphia. Here, we describe a family with Basan syndrome from South India with a novel SMARCAD1 variant (c.378+1delGTAA) affecting the known mutational hotspot in exon 1.

Lamellar ichthyosis with a novel NIPAL4 variant showing dramatic response to high-dose vitamin D therapy

Therapeutic options are limited in cases of autosomal recessive congenital ichthyosis with inadequate response to topical agents. Acitretin is the current standard of care in these patients, but its use is limited by cumulative toxicity when prolonged therapy is needed in children. There is evidence to suggest that high doses of vitamin D can normalize keratinization and suppress inflammatory cytokines. Here, we report a patient with lamellar ichthyosis with a novel mutation in the Nipa-like Domain-Containing 4 (NIPAL4) gene. High dose short-term vitamin D therapy was administered with a dramatic and sustained clinical response.

Reducing thermal crosstalk in ten-channel tunable slotted-laser arrays

Given the tight constraints on the wavelength stability of sources in optical networks, the thermal crosstalk between operating devices in a ten-channel thermally-tunable slotted laser array for DWDM applications has been investigated. It was found experimentally the current standard thermal solution with the laser array chip mounted on an AlN carrier does not allow for wavelength stability of ± 25 GHz ( ± 2 K) with a temperature rise of 5 K measured in a device with 100 mA (CW) applied to a neighbouring laser (device spacing = 360 µm). A combined experimental/numerical approach revealed solid state submounts comprising diamond or highly ordered pyrolytic graphite are inadequate to reduce crosstalk below an allowable level. Numerical simulations of advanced cooling technologies reveal a microfluidic enabled substrate would reduce thermal crosstalk between operational devices on the chip to acceptable levels. Critically our simulations show this reduced crosstalk is not at the expense of device tunability as the thermal resistance of individual lasers remains similar for the base and microfluidic cases.

Gelatinous transformation of bone marrow following chemotherapy for myeloma

Gelatinous transformation of the marrow (GTBM) has been associated with various conditions. We present a unique case of GTBM in a patient with myeloma following treatment with Melphalan.

X-ray structure of Escherichia coli pyridoxine 5'-phosphate oxidase complexed with FMN at 1.8 A resolution

BACKGROUND

Escherichia coli pyridoxine 5'-phosphate oxidase (PNPOx) catalyzes the terminal step in the biosynthesis of pyridoxal 5'-phosphate (PLP), a cofactor used by many enzymes involved in amino acid metabolism. The enzyme oxidizes either the 4'-hydroxyl group of pyridoxine 5'-phosphate (PNP) or the 4'-primary amine of pyridoxamine 5'-phosphate (PMP) to an aldehyde. PNPOx is a homodimeric enzyme with one flavin mononucleotide (FMN) molecule non-covalently bound to each subunit. A high degree of sequence homology among the 15 known members of the PNPOx family suggests that all members of this group have similar three-dimensional folds.

RESULTS

The crystal structure of PNPOx from E. coli has been determined to 1.8 A resolution. The monomeric subunit folds into an eight-stranded beta sheet surrounded by five alpha-helical structures. Two monomers related by a twofold axis interact extensively along one-half of each monomer to form the dimer. There are two clefts at the dimer interface that are symmetry-related and extend from the top to the bottom of the dimer. An FMN cofactor that makes interactions with both subunits is located in each of these two clefts.

CONCLUSIONS

The structure is quite similar to the recently deposited 2.7 A structure of Saccharomyces cerevisiae PNPOx and also, remarkably, shares a common structural fold with the FMN-binding protein from Desulfovibrio vulgaris and a domain of chymotrypsin. This high-resolution E. coli PNPOx structure permits predictions to be made about residues involved in substrate binding and catalysis. These predictions provide testable hypotheses, which can be answered by making site-directed mutants.