The adverse effects of prenatal alcohol exposure constitute a continuum of disabilities (fetal alcohol spectrum disorders [FASD]). In 1996, the Institute of Medicine established diagnostic categories delineating the spectrum but not specifying clinical criteria by which diagnoses could be assigned. In 2005, the authors published practical guidelines operationalizing the Institute of Medicine categories, allowing for standardization of FASD diagnoses in clinical settings. The purpose of the current report is to present updated diagnostic guidelines based on a thorough review of the literature and the authors' combined expertise based on the evaluation of >10 000 children for potential FASD in clinical settings and in epidemiologic studies in conjunction with National Institute on Alcohol Abuse and Alcoholismfunded studies, the Collaborative Initiative on Fetal Alcohol Spectrum Disorders, and the Collaboration on FASD Prevalence. The guidelines were formulated through conference calls and meetings held at National Institute on Alcohol Abuse and Alcoholism offices in Rockville, MD. Specific areas addressed include the following: precise definition of documented prenatal alcohol exposure; neurobehavioral criteria for diagnosis of fetal alcohol syndrome, partial fetal alcohol syndrome, and alcohol-related neurodevelopmental disorder; revised diagnostic criteria for alcoholrelated birth defects; an updated comprehensive research dysmorphology scoring system; and a new lip/philtrum guide for the white population, incorporating a 45-degree view. The guidelines reflect consensus among a large and experienced cadre of FASD investigators in the fields of dysmorphology, epidemiology, neurology, psychology, developmental/ behavioral pediatrics, and educational diagnostics. Their improved clarity and specificity will guide clinicians in accurate diagnosis of infants and children prenatally exposed to alcohol. abstract

Despite their clinical significance, characterization of balanced chromosomal abnormalities (BCAs) has largely been restricted to cytogenetic resolution. We explored the landscape of BCAs at nucleotide resolution in 273 subjects with a spectrum of congenital anomalies. Whole-genome sequencing revised 93% of karyotypes and revealed complexity that was cryptic to karyotyping in 21% of BCAs, highlighting the limitations of conventional cytogenetic approaches. At least 33.9% of BCAs resulted in gene disruption that likely contributed to the developmental phenotype, 5.2% were associated with pathogenic genomic imbalances, and 7.3% disrupted topologically associated domains (TADs) encompassing known syndromic loci. Remarkably, BCA breakpoints in eight subjects altered a single TAD encompassing MEF2C, a known driver of 5q14.3 microdeletion syndrome, resulting in decreased MEF2C expression. This study proposes that sequence-level resolution dramatically improves prediction of clinical outcomes for balanced rearrangements, and provides insight into novel pathogenic mechanisms such as altered regulation due to changes in chromosome topology.

WHAT'S KNOWN ON THIS SUBJECT: Most studies of fetal alcohol syndrome and fetal alcohol spectrum disorders (FASD) prevalence in the general population of the United States have been carried out using passive methods (surveillance or clinicbased studies), which underestimate rates of FASD. WHAT THIS STUDY ADDS:Using active case ascertainment methods among children in a representative middle class community, rates of fetal alcohol syndrome and total FASD are found to be substantially higher than most often cited estimates for the general US population. abstract OBJECTIVES: To determine the prevalence and characteristics of fetal alcohol spectrum disorders (FASD) among first grade students (6-to 7-year-olds) in a representative Midwestern US community. METHODS:From a consented sample of 70.5% of all first graders enrolled in public and private schools, an oversample of small children (#25th percentile on height, weight, and head circumference) and randomly selected control candidates were examined for physical growth, development, dysmorphology, cognition, and behavior. The children's mothers were interviewed for maternal risk. RESULTS:Total dysmorphology scores differentiate significantly fetal alcohol syndrome (FAS) and partial FAS (PFAS) from one another and from unexposed controls. Alcohol-related neurodevelopmental disorder (ARND) is not as clearly differentiated from controls. Children who had FASD performed, on average, significantly worse on 7 cognitive and behavioral tests and measures. The most predictive maternal risk variables in this community are late recognition of pregnancy, quantity of alcoholic drinks consumed 3 months before pregnancy, and quantity of drinking reported for the index child's father. From the final multidisciplinary case findings, 3 techniques were used to estimate prevalence. FAS in this community likely ranges from 6 to 9 per 1000 children (midpoint, 7.5), PFAS from 11 to 17 per 1000 children (midpoint, 14), and the total rate of FASD is estimated at 24 to 48 per 1000 children, or 2.4% to 4.8% (midpoint, 3.6%). (Continued on last page) CONCLUSIONS:

Dominant optic atrophy (DOA)1,2 and axonal peripheral neuropathy (Charcot-Marie-Tooth Type 2 or CMT2)3 are hereditary neurodegenerative disorders most commonly caused by mutations in the canonical mitochondrial fusion genes OPA1 and MFN2, respectively4. In yeast, homologs of OPA1(Mgm1) and MFN2(Fzo1) work in concert with Ugo15,6, which has no human equivalent to date7. By whole exome sequencing patients with optic atrophy and CMT2, we identified four families with recessive mutations in SLC25A46. We demonstrate that SLC25A46, like Ugo1, is a modified carrier protein that has been recruited to the outer mitochondrial membrane and interacts with the inner membrane remodeling protein, mitofilin(Fcj1). Loss-of-function in cultured cells and in zebrafish unexpectedly leads to increased mitochondrial connectivity, while severely affecting the development and maintenance of neurons in the fish. The discovery of SLC25A46 strengthens the genetic overlap between optic atrophy and CMT2, while exemplifying a novel class of modified solute transporters linked to mitochondrial dynamics.

Estimated prevalence of fetal alcohol spectrum disorders among first-graders in 4 US communities ranged from 1.1% to 5.0% using a conservative approach. These findings may represent more accurate US prevalence estimates than previous studies but may not be generalizable to all communities.

Brain malformations are individually rare but collectively common causes of developmental disabilities1–3. Many forms occur sporadically and have reduced reproductive fitness, pointing towards a causative role for de novo mutations4,5. Here we report our studies of Baraitser-Winter syndrome, a well-defined syndrome characterized by distinct craniofacial features, ocular colobomata and a neuronal migration defect6,7. By using whole-exome sequencing in three proband-parent trios, we identified de novo missense changes in the cytoplasmic actin genes ACTB and ACTG1 in one and two probands, respectively. Sequencing of both genes in fifteen additional patients revealed disease-causing mutations in all probands, including two recurrent de novo mutations (ACTB p.Arg196His and ACTG1 p.Ser155Phe). Our results confirm that trio-based exome sequencing is a powerful approach to discover the genes causing sporadic developmental disorders, emphasize the overlapping roles of cytoplasmic actins in development, and suggest that Baraitser-Winter syndrome is the predominant phenotype associated with mutations of these two genes.

(Abstracted from JAMA 2018;319(5):474–482) Several single-site, active-case ascertainment studies in the United States have shown widely varying prevalence estimates for fetal alcohol spectrum disorders, composed of fetal alcohol syndrome, partial fetal alcohol syndrome, and alcohol-related neurodevelopmental disorder. Prevalence of fetal alcohol spectrum disorders are challenging to estimate using routine surveillance methods, and cases are often misdiagnosed or undiagnosed.

Nicolaides-Baraitser syndrome (NBS) is characterized by sparse hair, distinctive facial morphology, distal-limb anomalies and intellectual disability. We sequenced the exomes of ten individuals with NBS and identified heterozygous variants in SMARCA2 in eight of them. Extended molecular screening identified nonsynonymous SMARCA2 mutations in 36 of 44 individuals with NBS; these mutations were confirmed to be de novo when parental samples were available. SMARCA2 encodes the core catalytic unit of the SWI/SNF ATP-dependent chromatin remodeling complex that is involved in the regulation of gene transcription. The mutations cluster within sequences that encode ultra-conserved motifs in the catalytic ATPase region of the protein. These alterations likely do not impair SWI/SNF complex assembly but may be associated with disrupted ATPase activity. The identification of SMARCA2 mutations in humans provides insight into the function of the Snf2 helicase family.