The authors' full names, academic degrees, and affiliations are listed in the Appendix. Dr. Peffault de Latour can be contacted at regis .

Analysis of the growth abnormalities in sickle cell disease has been limited by the lack of longitudinal observations in individuals, and by an inability to quantitate the observed patterns. To investigate the timing and pattern of the adolescent growth spurt, longitudinal observations of height from the Jamaican cohort study were fitted to a mathematical model of growth (Preece-Baines model 1). The

Background - Ischemic stroke is a devastating complication affecting children with sickle cell anemia (SCA). Genetic factors are likely to be important in determining the risk of stroke but are very poorly defined. Methods - We have studied a cohort of 19 children who had an overt ischaemic stroke before 4 years of age. We predicted genetic determinants of stroke would be more prominent in this group. We performed whole exome sequencing on this cohort and applied two hypotheses to our variant filtering. Firstly, we looked for very strong, potentially mono- or oligogenic variants for ischemic stroke and secondly, we considered that more common polygenic variants will be enriched in our cohort. Candidate variants emerging from both strategies were validated in a cohort of 283 patients with SCA and known pediatric cerebrovascular outcomes. We used principal component analysis in this cohort to control for relatedness and population substructure. Results - Our primary finding was that the APOE genotypes ε2/ε4 and ε4/ ε4, defined by the interplay of rs7412 and rs429358 , were associated with increased stroke risk, with an odds ratio of 4.35 (95% CI 1.85-10.0, p=0.0011) for ischemic stroke in the validation cohort. We also found that rs2297518 in NOS2 (OR 2.25 95%CI 1.21-4.19, p=0.014), and rs2230123 in STAT5a (OR=2.60, 95%CI 1.30-5.20 p=0.009) both had increased odds ratios for ischemic stroke, although these two variants were below the threshold for statistical significance after correction for multiple testing. Conclusions - These data identify new loci for future functional investigations into cerebrovascular disease in SCA. Based on African population reference allele frequencies, the APOE genotypes would be present in about 10% of children with SCA and represent a genetic risk factor that is potentially modifiable by both dietary and pharmaceutical manipulation of its dyslipidemic effects.

Background: Cigarette smoking is believed to accelerate age-related neurodegeneration. Despite significant sex differences in both smoking behaviors and brain structures, the active literature is equivocal in parsing out a sex difference in smoking-associated brain structural changes. Objective: The current study examined subcortical and lateral ventricle gray matter (GM) volume differences among smokers, active, past, and never-smokers, stratified by sex. Methods: The current study data included 1959 Dallas Heart Study (DHS) participants with valid brain imaging data. Stratified by gender, multiple-group comparisons of three cigarette-smoking groups were conducted to test whether there is any cigarette-smoking group differences in GM volumes of the selected regions of interest (ROIs). Results: The largest subcortical GM volumetric loss and enlargement of the lateral ventricle were observed among past smokers for both females and males. However, these observed group differences in GM volumetric changes were statistically significant only among males after adjusting for age and intracranial volumes. Conclusions: The study findings suggest a sex difference in lifetime-smoking-associated GM volumetric changes, even after controlling for aging and intracranial volumes.

Ischemic stroke is a devastating complication of sickle cell anemia (SCA) and can affect children from a very young age. It is the commonest cause of stroke in the general pediatric population. The peak incidence is in the first decade of life and approaches 11% in the absence of stroke prevention programmes. The advent of transcranial doppler (TCD) screening as part of a primary stroke prevention programme has reduced the incidence of stroke by 90%. However, not all strokes are prevented by TCD, and TCD abnormalities are not specific, with up to 60% children receiving transfusions unnecessarily. Understanding the underlying pathophysiology of cerebrovasculopathy in SCA and recognition of important risk factors will lead to a more stringent identification of the at-risk population. Analysis of siblings with stroke and abnormal TCDs offers good evidence that a proportion of this variability is conferred by inherited genetic variation. Identifying those specific variants has proved elusive, with many conflicting findings reported in the literature, no doubt reflecting the limited power of many studies to address the complex overlay of environmental and genetic influences. To attempt to minimise the impact of non-genetic confounders, our study looked specifically at children who had an overt ischemic stroke or developed abnormal TCD measurements (TAMMV >200cm/s) prior to their 4th birthday, in the absence of potentially precipitating acute medical events. We recruited 22 patients, 19 of whom had an ischemic stroke, and 3 who developed abnormal TCD measurements, prior to 4 yrs of age. Additionally, we recruited the dizygotic twin of one stroke case, who had SCA, but, importantly, no cerebrovascular complications, as confirmed by MRI/A aged 15 yrs. We extracted DNA from peripheral blood samples. Exome library was prepared using Agilent SureSelect XT V7, sequencing was performed using Illumina NovaSeq. Alignment, assembly, variant calling and annotation were based on a GATK Best Practices workflow. For each sample, around 15000 non-synonymous variants were identified. Across the 22 case samples, 58 variants in 56 genes were predicted to be pathogenic or likely pathogenic, as determined with InterVar. These variants were interpreted with respect to dbSNP documentation and biological role of the gene they affected. Variant segregation within the twin pair was also considered. Two patients were homozygous for rs429358, a missense variant in the APOE gene that is pathogenic for familial hyperlipoproteinemia, type 3. Moreover, 3 further patients were compound heterozygous for this variant plus another APOE missense variant pathogenic for the same condition, rs7412. One of these 3 cases was the affected sibling of the twin pair and notably, the unaffected twin carried only heterozygous rs429358 and not rs7412. A further patient was heterozygous for rs121908043 in the LDL-R gene, which is pathogenic of Familial Hypercholesterolaemia, even in the heterozygous state. Finally, in an additional patient, we identified a potential compound heterozygote of a known pathogenic variant, rs118204068 with another missense variant rs11542065 in the LPL gene, to cause Hyperlipoproteinemia type 1. We have used whole exome sequencing to analyse patients with sickle cell anemia and stroke at a very young age, an extreme phenotype, in whom we predicted genetic factors would be a significant cause of stroke. We found 7 of the 22 patients (32%) had variants diagnostic of inherited dysplipidaemias, including 5 with familial hyperlipoproteinemia type 3, 1 with hyperlipoproteinemia type 1 and one with familial hypercholesterolemia. Our analysis included one twin set and it is noteworthy that the unaffected twin sibling did not carry the necessary variants defining the inherited dyslipidaemia. These conditions are characterised by improper breakdown and accumulation of LDL-C, triglycerides and cholesterol, which has been associated with vascular dysfunction and hemolysis in SCA and are strongly associated with stroke and cardiovascular disease in the general population. This is potentially an important finding that warrants further investigation into the role of lipids and hyperlipidemia in the development of stroke and cerebral vasculopathy in the sickle cell population. In the long term, we suggest that measurement, and potentially, control of lipids may form a component of the primary stroke prevention programme. Disclosures Brousse: Add medica: Consultancy; bluebird bio: Consultancy. Rees:Novartis: Other: Strategic advisory role,Principal investigator,sickle cell disease2.6 Investigator; Astra Zeneca (ticagrelor): Other: Data monitoring committees; TauRx (methylene blue): Other: Data monitoring committees; Alnylam: Other: Principal investigator; Global Blood Therapeutics: Other: Strategic advisory role; Celgene: Other: Strategic advisory role; Emmaus: Other: Strategic advisory role; Agios: Other: Grants.