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The high cycle fatigue (HCF) properties of direct metal laser sintering (DMLS) of Ti6Al4V (ELI) in three mutually orthogonal build directions were investigated by cycling specimens under load control, in a tension-tension fatigue testing machine. Semi-log graphs of maximum stress (S) against life (N) of the specimens produced along the respective three build directions were plotted, and the displayed endurance limits compared. Optical and scanning electron microscopy were used to compare and analyse the crack initiation and propagation characteristics of the specimens. The influence of the build direction on the fatigue properties of the tested specimens is discussed here.

Alloying Pt with Rh significantly enhances the high temperature stress rupture strength and maintains both oxidation and corrosion resistance at elevated temperatures. Such unique property combination renders Pt-Rh alloys mainstay in space technology, glass and chemical industries. However, the exponential increase in the price of Rh in the past few years stirs an industrial concern. As a result, some industries are beginning to search for alternative alloys that can offer similar properties. This study conducted first-principles calculations to generate structural and elasticity data on binary Pt-Rh alloys using both supercell and virtual crystal approximation (VCA) approaches, to serve as a benchmark for new alternative Pt-based alloys.

The quantification of the density of defects in materials through non-destructive methods is of great interest to scientists and engineers. X-ray diffraction (XRD) peak profile analysis is a valuable method that is often used to reveal important microstructural information, such as defects present in crystalline materials as well as crystallite size. In this study, the broadening of XRD peaks of martensitic Ti6Al4V (ELI) produced by laser powder bed fusion (LPBF) was studied following modified Williamson-Hall (MWH) and Warren-Averbach (WA) analytical methods. The level of defects in martensitic LPBF Ti6Al4V (ELI) was found to drastically reduce by at least 73% after exposing the material to stress-relieving heat treatment.

Lattice structures are useful in the automotive, biomedical, and aerospace engineering fields because of their good mechanical properties. The efficacy with which their geometries are designed influences their load-bearing capacity. The methods of generating different types of lattice structures have not been clearly outlined in literature. Furthermore, their applicability and shortcomings in trying to mimic biological cellular structures remain to be well investigated. In this paper, numerous types of lattice structures prevalent in literature are highlighted and their tessellation described. The paper also explores the application of lattice structures in terms of their capabilities and limitations, in mimicking cellular structures in nature.

Process parameters of selective laser melting, such as track height, track width and depth of penetration, affect the characteristics of laser fused single tracks. The properties of additively manufactured 3D parts depend strongly on the quality of laser melted single tracks and resultant single layers. Layers formed with a good depth of laser penetration provide strong bonding between consecutive layers and the substrate. Poor depth of laser penetration leads to delamination of layers. In this study the effect of the critical process parameters of laser power, laser scanning speed, and laser linear energy density on the characteristics of SiC/Ti6Al4V(ELI) single tracks at different SiC volume fractions (5 %, 10 %, 15 %, 20 %, 25 % and 30%) was investigated. Phenomena, such as the keyhole effect, pre-balling, and balling of single tracks, were also investigated. The obtained results showed that increase of power at a constant speed increase both the track width and depth of penetration but the track height above the substrate is decreased.

The uptake of laser powder bed fusion for polymers has remained limited mainly because the interaction between material properties and process parameters is not well understood. The constraints of experimentally determining the optimal process parameters for new polymers in laser powder bed fusion include high expense, time-consumption, errors, and considerable effort. Hence, the need for using analytical and numerical models as alternatives. This paper starts with a summary on laser powder bed fusion of polymers, reviews the aspects of the process requiring the use of analytical and numerical tools, limitations, and possible improvements of the existing studies on the analytical models, and finally briefly explores approaches for numerical modelling of laser powder bed fusion of polymers. Some of the key aspects of the process that have been identified as being amenable to modelling include powder spreading and deposition of the layers, interaction between the laser beam and powder particles, melting and fusion of the particles, powder bed surface temperature, heat transfer through the powder, cooling phase, and the properties of printed parts. It is suggested in the study that the existing analytical and/or numerical models can be improved by increasing relevant variables (process parameters and material characteristics) used in them.

Metal matrix composites possess good mechanical properties at high temperatures making them good candidates for components that operate in conditions of high temperatures where they have to withstand static creep and cyclic fatigue loads. The mechanical properties of Ti6Al4V including hardness, strength, modulus of elasticity, and wear resistance can be enhanced with nano particulates to obtain lighter and stronger materials that can function at elevated temperatures. This paper starts with a brief background on composite materials and then turns to analysis of carbon nanotubes, titanium carbide, silicon carbide, titanium boride, titanium diboride, and titanium nitride nano particulate materials as candidates for the reinforcement for Ti6Al4V to form composites for aerospace applications. Based on a comparison of their physical properties of melting point, coefficient of thermal expansion, density and mechanical properties of strength, Young's modulus and hardness all obtained from literature, the paper narrows down on multiwalled carbon nanotubes and titanium diboride as the preferred nano composites for this use. Presently, experimental work is under way to determine optimum process parameters for additively built carbon nanotube/Ti6Al4V composites that will be used to build three-dimensional specimens for testing to determine their mechanical properties. This is expected to clarify the value of incorporating the carbon nanotubes in the Ti6Al4V matrix with respect to selected mechanical properties. Future work is envisaged on additively build titanium diboride/Ti6Al4V composites to the same end and in order to determine which of the two nano particles is best in enhancing the mechanical properties of Ti6Al4V.

Additive manufacturing (AM), is one of the key components of the 4th industrial revolution. Polymer laser sintering (PLS) is a subset of AM that is commonly used to process polymers, and which achieves good surface finish, good mechanical properties of finished products and for which there is no need for support structures. However, the requirements for polymeric powder for PLS are strident. Moreover, PLS subjects polymeric feed powders to high temperatures that lead to degradation of their thermal, rheological, and physical properties and is thus an impediment to their recyclability. Therefore, it is imperative to investigate the degree of polymer degradation or aging before re-using the material. This paper reviews the common techniques that are employed to characterize the suitability of polymeric powders for use and re-use in the PLS process. These include, but are not limited to, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), laser diffraction analysis, gas pycnometry, scanning electron microscopy (SEM), and melt flow index (MFI) testing.

Combined numerical modelling and topology optimisation methods are useful in the design and analysis of engineering structures. The two tools are used to predict and optimise the mechanical properties of structures. Numerical modelling and optimisation of three-dimensional honeycomb structures is challenged by the sharp angles in its geometry. This reduces effective iterations in topology optimisation at the vertices and edges. The alternative - generating effective iterations at the vertices and edges in planar honeycombs of Ti6Al4V (ELI) - is presented in this paper. Mesh convergence tests with varying mesh densities were conducted on planar unit hexagonal cells at the start. The results obtained from planar unit hexagonal cells under out-of-plane compression loads before and after topology optimisation were compared. This was followed by shape optimisation and numerical analysis, and the results were compared with the numerical analysis before topology optimisation. The same procedure was followed for a planar honeycomb model. Acceptable predictions were obtained for the planar numerical models. Material reductions of 30% and 8% for the planar unit hexagon cell and for the honeycomb model respectively were obtained in topology optimisation. The maximum stresses in these numerical models after shape optimisation reduced by 58% and 4% respectively. [ABSTRACT FROM AUTHOR]

The tensile and high cycle fatigue (HCF) properties of high temperature annealed (HTA) direct metal laser sintered (DMLS) Ti6Al4V extra low interstitial (ELI) machined and polished specimens were investigated. The HTA heat treatment of the specimens resulted in the nucleation and growth of the alpha and beta grains from the acicular α' martensite grains, improving their elongation to failure. The specimens were micro-CT scanned in an attempt to relate the pores in the specimens to their fatigue properties. The micro-CT pore information from suspected crack initiation pores on the surfaces of eventual fracture was used to calculate the stress intensity factors, which correlated well with the decreasing cycles to failure of the fatigue test specimens for all three build directions. Three representative specimens were analysed, and the 'killer pore' was identified in each micro-CT scan and fractograph, all of which were proximal to the surface of the specimen. [ABSTRACT FROM AUTHOR]

Silicon carbide (SiC) exhibits intriguing thermo-physical properties such as higher heat capacity and conductivity, as well as a lower density than Ti6Al4V(ELI). These properties make SiC a good candidate for the reinforcement of Ti6Al4V(ELI) with respect to its use as a heat shield in aero turbines to increase their efficiency. The traditional materials used in aircraft structures were required to have a combination of good mechanical properties such as strength, stiffness, and hardness and low weight, as well as low thermo-physical properties such as coefficient of thermal expansion (CTE) and thermal conductivity. The alloy Ti6Al4V(ELI) has a density of 4.45 g/cm 3 , which is lower than that of structural steel (7.4 g/cm 3 ) and higher than that of aluminium (2.5 g/cm 3 ). Lower density benefits light weighting. Aluminium is the lightest of the traditional materials used but has relatively low strength. The CTE of SiC of 4.6 × 10 -6 /K is lower than that of Ti6Al4V(ELI) of 8.6 × 10 -6 /K, while the density of SiC of 3.21 g/cm 3 is lower than that of Ti6Al4V(ELI) of 4.45 g/cm 3 . Therefore, from the theory of composites, SiC/Ti6Al4V(ELI) composites are expected to have lower densities and CTEs than those of Ti6Al4V(ELI), thus providing for lightweighting and less thermal related buckling or separation at their joints with carbon/epoxy resin panels. The specific strength, stiffness, and Knoop hardness of SiC of 75-490 kNm/kg, 132 MNm/kg, and 600-3800 GPa, respectively, are generally larger than those of Ti6Al4V(ELI) of 211 KNm/kg, 24 MNm/kg, and 880 GPa, respectively. Therefore, investigating reinforcement of Ti6Al4V(ELI) with SiC particles is worthwhile as it will lead to the formation of composites that are stronger, stiffer, harder, and lighter, with lower values of CTE. For additive manufacturing, this requires initial studies to optimise the process parameters of laser power and scanning speed for single tracks. To print single tracks in the present work, different laser powers ranging from 100 W to 350 W and scanning speeds ranging from 0.3 m/s to 2.7 m/s were used for different SiC volume fraction values of values. To print single layers, different values of hatch distance were used together with the best values of laser power and scanning speed determined elsewhere by the authors for different volume fractions of SiC. Through optical microscopy, the built tracks and their cross sections were examined. By using laser power and scanning speeds of 200 W and 1.2 m/s, and 150 W and 0.8 m/s, respectively, the best tracks at 5% and 10% volume fractions were obtained, whereas the best tracks at 25% volume fraction were achieved using a laser power of 200 W and a scanning speed of 0.5 m/s. Furthermore, the results showed that the maximum SiC volume percentage of 30% resulted in limited or no penetration. Therefore, it is concluded from the study that parts with improved mechanical properties can be produced at SiC volume fractions ranging from 5% to 25%, while parts produced at the high volume fraction of 30% would have unacceptable mechanical qualities for the final part., Competing Interests: The authors declare no conflicts of interest.

Background: Breast cancer (BC) risk prediction models consider cancer family history (FH) and germline pathogenic variants (PVs) in risk genes. It remains elusive to what extent complementation with polygenic risk score (PRS) and non-genetic risk factor (NGRFs) data affects individual intensified breast surveillance (IBS) recommendations according to European guidelines., Methods: For 425 cancer-free women with cancer FH (mean age 40·6 years, range 21-74), recruited in France, Germany and the Netherlands, germline PV status, NGRFs, and a 306 variant-based PRS (PRS 306 ) were assessed to calculate estimated lifetime risks (eLTR) and estimated 10-year risks (e10YR) using CanRisk. The proportions of women changing country-specific European risk categories for IBS recommendations, i.e. ≥20 % and ≥30 % eLTR, or ≥5 % e10YR were determined., Findings: Of the women with non-informative PV status, including PRS 306 and NGRFs changed clinical recommendations for 31·0 %, (57/184, 20 % eLTR), 15·8 % (29/184, 30 % eLTR) and 22·4 % (41/183, 5 % e10YR), respectively whereas of the women tested negative for a PV observed in their family, clinical recommendations changed for 16·7 % (25/150), 1·3 % (2/150) and 9·5 % (14/147). No change was observed for 82 women with PVs in high-risk genes (BRCA1/2, PALB2). Combined consideration of eLTRs and e10YRs identified BRCA1/2 PV carriers benefitting from IBS <30 years, and women tested non-informative/negative for whom IBS may be postponed., Interpretation: For women who tested non-informative/negative, PRS and NGRFs have a considerable impact on IBS recommendations. Combined consideration of eLTRs and e10YRs allows personalizing IBS starting age., Funding: Horizon 2020, German Cancer Aid, Federal Ministry of Education and Research, Köln Fortune., Competing Interests: Declaration of competing interest The authors declare no conflicts of interest., (Copyright © 2023 The Authors. Published by Elsevier Ltd.. All rights reserved.)

In the present study, recyclability of Laser PP CP 75 polypropylene powder from Diamond Plastics GmbH was determined by characterizing and comparing the used powder after each cycle with material from previous cycles and with fresh powder. The melt flow index of Laser PP CP 75 was affected by recycling since it was observed to change by 30.62% after the 8th 100% re-use cycle, a lower value than PA 12 of 66.04%, for the 6th re-use cycle. Parts printed with virgin Laser PP CP 75 had an average dimensional error of 3.02% (virgin material) and 4.06% after the 4th 100% re-use cycle, which raises concerns about the commercial viability of the material. After the 4th re-use cycle, the printed parts had distorted edges and failed to print after the 9th print cycle. Lastly, tensile testing revealed a skewed bell-shaped curve of strength versus the number of recycles with the highest ultimate tensile strength occurring for the second 100% re-use cycle (7.4 MPa). The curves for elastic modulus and percentage elongation were inverted with minimum points for the 2nd 100% re-use cycle. Overall, the experimental work confirmed that the properties of polypropylene powder were affected by recycling in polymer laser sintering, but the powder exhibited superior characteristics upon recycling to those of the predominantly used PA 12 powder.

Numerical models can be useful for analysis of the ability of structural engineering materials to withstand harsh environmental conditions such as dynamic loading. In the present study, a microstructure-variable-based numerical model for predicting the high strain rate and temperature properties of different microstructures of Ti6Al4V (ELI-Extra Low Interstitial) produced by laser-based powder bed fusion is proposed. The model was implemented in two different subroutines, VUMAT and VUHARD, available in ABAQUS/Explicit for simulating dynamic conditions. The two subroutines were then used to simulate the split Hopkinson pressure bar (SHPB) experiments to study the flow properties of various forms of the direct metal laser sintered Ti6Al4V(ELI) alloy at various conditions of strain rate and temperature. Comparison of the results obtained through simulation and those obtained from experimental testing showed high degrees of correlation and accuracy with correlation coefficients and absolute percentage errors >0.97 and <4%, respectively. The numerical model was also shown to give good predictions of the strain hardening and dynamic recovery phenomena that prevail for deformations at high strain rates and temperatures.

Numerical modelling and simulation can be useful tools in qualification of additive manufactured parts for use in demanding structural applications. The use of these tools in predicting the mechanical properties and field performance of additive manufactured parts can be of great advantage. Modelling and simulation of non-linear material behaviour requires development and implementation of constitutive models in finite element analysis software. This paper documents the implementation and verification process of a microstructure-variable based model for DMLS Ti6Al4V (ELI) in two separate ABAQUS/Explicit subroutines, VUMAT and VUHARD, available for defining the yield surface and plastic deformation of materials. The verification process of the implemented subroutines was conducted for single and multiple element tests with varying prescribed loading conditions. The simulation results obtained were then compared with the analytical solutions at the same conditions of strain rates and temperatures. This comparison showed that both developed subroutines were accurate in predicting the flow stress of various forms of DMLS Ti6Al4V (ELI) under different conditions of strain rates and temperatures.

Dislocations play a central role in determining strength and flow properties of metals and alloys. Diffusionless phase transformation of β→α in Ti6Al4V during the Direct Metal Laser Sintering (DMLS) process produces martensitic microstructures with high dislocation densities. However, heat treatment, such as stress relieving and annealing, can be applied to reduce the volume of these dislocations. In the present study, an analysis of the X-ray diffraction (XRD) profiles of the non-heat-treated and heat-treated microstructures of DMLS Ti6Al4V(ELI) was carried out to determine the level of defects in these microstructures. The modified Williamson-Hall and modified Warren-Averbach methods of analysis were used to evaluate the dislocation densities in these microstructures. The results obtained showed a 73% reduction of dislocation density in DMLS Ti6Al4V(ELI) upon stress relieving heat treatment. The density of dislocations further declined in microstructures that were annealed at elevated temperatures, with the microstructures that were heat-treated just below the β→α recording the lowest dislocation densities.

Comparably little is known about breast cancer (BC) risks in women from families tested negative for BRCA1/2 mutations despite an indicative family history, as opposed to BRCA1/2 mutation carriers. We determined the age-dependent risks of first and contralateral breast cancer (FBC, CBC) both in noncarriers and carriers of BRCA1/2 mutations, who participated in an intensified breast imaging surveillance program. The study was conducted between January 1, 2005, and September 30, 2017, at 12 university centers of the German Consortium for Hereditary Breast and Ovarian Cancer. Two cohorts were prospectively followed up for incident FBC (n = 4,380; 16,398 person-years [PY], median baseline age: 39 years) and CBC (n = 2,993; 10,090 PY, median baseline age: 42 years). Cumulative FBC risk at age 60 was 61.8% (95% CI 52.8-70.9%) for BRCA1 mutation carriers, 43.2% (95% CI 32.1-56.3%) for BRCA2 mutation carriers and 15.7% (95% CI 11.9-20.4%) for noncarriers. FBC risks were significantly higher than in the general population, with incidence rate ratios of 23.9 (95% CI 18.9-29.8) for BRCA1 mutation carriers, 13.5 (95% CI 9.2-19.1) for BRCA2 mutation carriers and 4.9 (95% CI 3.8-6.3) for BRCA1/2 noncarriers. Cumulative CBC risk 10 years after FBC was 25.1% (95% CI 19.6-31.9%) for BRCA1 mutation carriers, 6.6% (95% CI 3.4-12.5%) for BRCA2 mutation carriers and 3.6% (95% CI 2.2-5.7%) for noncarriers. CBC risk in noncarriers was similar to women with unilateral BC from the general population. Further studies are needed to confirm whether less intensified surveillance is justified in women from BRCA1/2 negative families with elevated risk., (© 2019 UICC.)

Background: Biallelic BRCA1 mutations are regarded either embryonically lethal or to cause Fanconi anemia (FA), a genomic instability syndrome characterized by bone marrow failure, developmental abnormalities, and cancer predisposition. We report biallelic BRCA1 mutations c.181T > G (p.Cys61Gly) and c.5096G > A (p.Arg1699Gln) in a woman with breast cancer diagnosed at the age of 30 years. The common European founder mutation p.Cys61Gly confers high cancer risk, whereas the deleterious p.Arg1699Gln is hypomorphic and was suggested to confer intermediate cancer risk., Methods and Results: Aside from significant toxicity from chemotherapy, the patient showed mild FA-like features (e.g., short stature, microcephaly, skin hyperpigmentation). Chromosome fragility, a hallmark of FA patient cells, was not present in patient-derived peripheral blood lymphocytes. We demonstrated that the p.Arg1699Gln mutation impairs DNA double-strand break repair, elevates RAD51 foci levels at baseline, and compromises BRCA1 protein function in protecting from replication stress. Although the p.Arg1699Gln mutation compromises BRCA1 function, the residual activity of the p.Arg1699Gln allele likely prevents from chromosome fragility and a more severe FA phenotype., Conclusion: Our data expand the clinical spectrum associated with biallelic BRCA1 mutations, ranging from embryonic lethality to a mild FA-like phenotype and no chromosome fragility., (© 2019 The Authors. Molecular Genetics & Genomic Medicine published by Wiley Periodicals, Inc.)

Background: Monogenic forms of diabetes are often diagnosed by chance, due to the variety of clinical presentation and limited experience of the diabetologists with this kind of diabetes. Aim of this study was to evaluate clinical parameters for an efficient screening., Methods: Clinical parameters were: negative diabetes-specific antibodies at onset of diabetes, positive family history of diabetes, and low to moderate insulin requirements after one year of diabetes treatment. Molecular testing was performed through sequencing of the programming regions of HNF-4alpha (MODY 1), glucokinase (MODY 2) and HNF-1alpha/TCF1 (MODY 3) and in one patient the HNF-1beta/TCF2 region (MODY 5). 39 of 292 patients treated with insulin were negative for GADA and IA2A, and 8 (20.5%) patients fulfilled both other criteria., Results: Positive molecular results were found in five (63%) patients (two with MODY 2, two with MODY 3, one with MODY 5). At diabetes onset, the mean age of the 5 patients with MODY was 10.6 ± 5.3 yrs (range 2.6-15 yrs), HbA(1c) was 8.4 ± 3.1 % (6.5-13.9%), mean diabetes duration until diagnosis of MODY was 3.3 ± 3.6 yrs (0.8-9.6 yrs) with insulin requirements of 0.44 ± 0.17 U/kg/d (0.2-0.6 U/kg/d). Patients with MODY 3 were changed from insulin to repaglinide, those with MODY 2 were recommended discontinuing insulin treatment., Conclusion: In patients with negative diabetes-specific antibodies at onset of diabetes, with a positive family history, and low to moderate insulin needs a genetic screening for MODY is indicated. Watchful consideration of these clinical parameters may lead to an early genetic testing, and to an adequate treatment., (© Georg Thieme Verlag KG Stuttgart · New York.)

Aims: HNF1B-maturity-onset diabetes of the young is caused by abnormalities in the HNF1B gene encoding the transcription factor HNF-1beta. We aimed to investigate detailed clinical features and the type of HNF1B gene anomaly in five pediatric cases with HNF1B-MODY., Methods: From a cohort of 995 children and adolescents with diabetes, we analyzed the most frequent maturity-onset diabetes of the young genes (GCK, HNF1A, HNF4A) including HNF1B sequencing and deletion analysis by quantitative Multiplex-PCR of Short Fluorescent Fragments (QMPSF) if patients were islet autoantibody-negative and had one parent with diabetes or associated extrapancreatic features or detectable C-peptide outside honeymoon phase. Presence and size of disease-causing chromosomal rearrangements detected by QMPSF were further analyzed by array comparative genomic hybridization., Results: Overall, five patients had a heterozygous HNF1B deletion, presenting renal disease, elevated liver enzymes, and diabetes. Diabetes was characterized by insulin resistance and adolescent onset of hyperglycemia. Additionally, clinical features in some patients were pancreas dysplasia and exocrine insufficiency (two of five patients), genital defects (three of five), mental retardation (two of five), and eye abnormalities (coloboma, cataract in two of five). One case also had severe growth deficit combined with congenital cholestasis, and another case had common variable immune deficiency. All patients reported here had monoallelic loss of the entire HNF1B gene. Whole genome array comparative genomic hybridization confirmed a precurrent genomic deletion of approximately 1.3-1.7 Mb in size., Conclusion: The clinical data of our cases enlarge the wide spectrum of patients with HNF1B anomaly. The underlying molecular defect in all cases was a 1.3- to 1.7-Mb deletion, and paired, segmental duplications along with breakpoints were most likely involved in this recurrent chromosomal microdeletion.

Glucokinase hyperinsulinism is a rare variant of congenital hyperinsulinism caused by activating mutations in the glucokinase gene and has been reported so far to be a result of overactivity of glucokinase within the pancreatic beta-cell. Here we report on a new patient with difficulties to diagnose persistent hyperinsulinism and discuss diagnostic procedures of this as well as the other reported individuals. After neonatal hypoglycemia, the patient was reevaluated at the age of 3 years for developmental delay. Morning glucose after overnight fast was 2.5-3.6 mmol/l. Fasting tests revealed supressed insulin secretion at the end of fasting (1.4-14.5 pmol/l). In addition, diagnostic data of the patients reported so far were reviewed. A novel heterozygous missense mutation in exon 10 c.1354G>C (p.Val452Leu) was found and functional studies confirmed the activating mutation. There was no single consistent diagnostic criterion found for our patient and glucokinase hyperinsulinism individuals in general. Often at the time of hypoglycemia low insulin levels were found. Therefore insulin concentrations at hypoglycemia, or during fasting test as well as reactive hypoglycemia after an oral glucose tolerance test were not conclusive for all patients. A glucose lowering effect in extra-pancreatic tissues independent from hyperinsulinism that results in diagnostic difficulties may contribute to underestimation of glucokinase hyperinsulinism. Mutational analysis of the GCK-gene should be performed in all individuals with unclear episodes of hypoglycemia even without documented hyperinsulinism during hypoglycemia. Delay of diagnosis might result in mental handicap of the affected individuals.

We describe a girl aged 10.5 years with hyperglycemia, whose mother and maternal father had insulin treated diabetes since adolescence. Using genetic analysis in mother and child, we identified identical new mutation of the HNF-1alpha sequence. Treatment with small doses of sulphonylurea was initiated and that therapy gave good results.