A novel p.Gly417Valfs*12 mutation in the MTTP gene causing abetalipoproteinemia: Presentation of the first patient in Mexico and analysis of the previously reported cases

BackgroundOur aims were to describe the first Mexican patient with abetalipoproteinemia and to perform a comparative analysis of biochemical, clinical, and genetic characteristics of 100 cases reported in the literature.MethodsWe performed biochemical and molecular screenings in a Mexican girl with extremely low lipid levels and in her family. Further, we integrated and evaluated the characteristics of the cases with abetalipoproteinemia described in the literature.ResultsOur patient is a six‐year‐old girl who presented vomiting, chronic diarrhea, failure to thrive, malabsorption, acanthocytosis, anemia, transaminases elevation, and extremely low lipid levels. MTTP gene sequencing revealed homozygosity for a novel mutation p.Gly417Valfs*12 (G deletion c.1250). With the analysis of the reported cases, 60 clinical features (14 classical and 46 non‐classical) were observed, being the most common acanthocytosis (57.5%), malabsorption (43.7%), and diarrhea (42.5%); 48.8% of the patients presented only classic clinical features, while the remaining 51.2% developed secondary effects due to a fat‐soluble vitamin deficiency. An odds ratio analysis disclosed that patients diagnosed after 10 years of age have an increased risk for presenting clinical complications (OR = 18.0; 95% CI 6.0‐54.1, p < 0.0001). A great diversity of mutations in MTTP has been observed (n = 76, being the most common p.G865X and p.N139_E140) and some of them with possible residual activity.ConclusionThe first Mexican patient with abetalipoproteinemia presents a novel MTTP mutation p.Gly417Valfs*12. Three factors that could modulate the phenotype in abetalipoproteinemia were identified: age at diagnosis, treatment, and the causal mutation.     

Effectiveness of chondrofascial ‘cigar’ graft in contouring the nasal dorsum

Irregularities of the nasal dorsum after rhinoplasty are frustrating for the patient and the surgeon. Different grafts and implants have been adopted to camouflage this nasal imperfection. This study was performed to assess the outcome of a composite chondrofascial ‘cigar’ graft for contouring an irregular nasal dorsum. Thirty-six patients who underwent rhinoplasty between May 2014 and October 2016 were studied prospectively. The cartilaginous core of the graft was obtained from the septal or conchal cartilage, while the graft outer sleeve was harvested from the right lateral thigh fascia lata. The graft was secured over the nasal dorsum through an external rhinoplasty approach. The patients were followed up for at least 18 months postoperative. All participants were evaluated objectively by two independent rhinoplasty surgeons and subjectively by Rhinoplasty Outcome Evaluation (ROE) score. Donor site morbidity was also assessed. All patients had satisfactory aesthetic results with no apparent irregularities detected over the nasal dorsum. The ROE score improved, from a mean of 20.94 ± 8.67 (range 8–58) preoperatively to a mean of 79.56 ± 10.65 (range 50–96) postoperatively. Insignificant donor site morbidity was encountered, with inconsequential effects. The chondrofascial cigar graft is a reliable method for contouring dorsal irregularities, particularly in patients with thin nasal skin.     

Nonexponential T2* decay in white matter

Visualizing myelin in human brain may help the study of diseases such as multiple sclerosis. Previous studies based on T₁ and T₂ relaxation contrast have suggested the presence of a distinct water pool that may report directly on local myelin content. Recent work indicates that T₂* contrast may offer particular advantages over T₁ and T₂ contrast, especially at high field. However, the complex mechanism underlying T₂* relaxation may render interpretation difficult. To address this issue, T₂* relaxation behavior in human brain was studied at 3 and 7 T. Multiple gradient echoes covering most of the decay curve were analyzed for deviations from mono‐exponential behavior. The data confirm the previous finding of a distinct rapidly relaxing signal component (T₂* ～ 6 ms), tentatively attributed to myelin water. However, in extension to previous findings, this rapidly relaxing component displayed a substantial resonance frequency shift, reaching 36 Hz in the corpus callosum at 7 T. The component's fractional amplitude and frequency shift appeared to depend on both field strength and fiber orientation, consistent with a mechanism originating from magnetic susceptibility effects. The findings suggest that T₂* contrast at high field may be uniquely sensitive to tissue myelin content and that proper interpretation will require modeling of susceptibility‐induced resonance frequency shifts. Magn Reson Med, 2011. © 2011 Wiley‐Liss, Inc.