Microdeletions of 1q43q44 result in a recognizable clinical disorder characterized by moderate to severe intellectual disability (ID) with limited or no expressive speech, characteristic facial features, hand and foot anomalies, microcephaly (MIC), abnormalities (agenesis/hypogenesis) of the corpus callosum (ACC), and seizures (SZR). Critical regions have been proposed for some of the more prominent features of this disorder such as MIC and ACC, yet conflicting data have prevented precise determination of the causative genes. In this study, the largest of pure interstitial and terminal deletions of 1q43q44 to date, we characterized 22 individuals by high-resolution oligonucleotide microarray-based comparative genomic hybridization. We propose critical regions and candidate genes for the MIC, ACC, and SZR phenotypes associated with this microdeletion syndrome. Three cases with MIC had small overlapping or intragenic deletions of AKT3, an isoform of the protein kinase B family. The deletion of only AKT3 in two cases implicates haploinsufficiency of this gene in the MIC phenotype. Likewise, based on the smallest region of overlap among the affected individuals, we suggest a critical region for ACC that contains ZNF238, a transcriptional and chromatin regulator highly expressed in the developing and adult brain. Finally, we describe a critical region for the SZR phenotype which contains three genes (FAM36A, C1ORF199, and HNRNPU). Although ~90% of cases in this study and in the literature fit these proposed models, the existence of phenotypic variability suggests other mechanisms such as variable expressivity, incomplete penetrance, position effects, or multigenic factors could account for additional complexity in some cases.

Normal development of the genitourinary (GU) tract is a complex process that frequently goes awry. In male children the most frequent congenital GU anomalies are cryptorchidism (1–4%), hypospadias (1%) and micropenis (0.35%). Bladder exstrophy and epispadias complex (BEEC) (1∶47000) occurs less frequently but significantly impacts patients' lives. Array comparative genomic hybridization (aCGH) identified seven individuals with overlapping deletions in the 2p15 region (66.0 kb-5.6 Mb). Six of these patients have GU defects, while the remaining patient has no GU defect. These deletions encompass the transcription factor OTX1. Subjects 2–7 had large de novo CNVs (2.39–6.31 Mb) and exhibited features similar to those associated with the 2p15p16.1 and 2p15p14 microdeletion syndromes, including developmental delay, short stature, and variable GU defects. Subject-1 with BEEC had the smallest deletion (66 kb), which deleted only one copy of OTX1. Otx1-null mice have seizures, prepubescent transient growth retardation and gonadal defects. Two subjects have short stature, two have seizures, and six have GU defects, mainly affecting the external genitalia. The presence of GU defects in six patients in our cohort and eight of thirteen patients reported with deletions within 2p14p16.1 (two with deletion of OTX1) suggest that genes in 2p15 are important for GU development. Genitalia defects in these patients could result from the effect of OTX1 on pituitary hormone secretion or on the regulation of SHH signaling, which is crucial for development of the bladder and genitalia.

Therapeutics harnessing the power of personalized medicine have the potential to revolutionize healthcare. Companion diagnostics are critical to this goal and are increasingly relied upon to ensure the effective, safe development and use of a personalized therapeutic. Companion diagnostics are the focus of several recent regulatory guidance documents; the drug-diagnostic codevelopment process has become increasingly relevant and necessary. Despite this, the promise of companion diagnostics has not been fully realized and there are multiple difficulties that still need resolution. The path to codevelop a successful companion diagnostic with its complementary drug is complex, fragmented and fraught with several challenges. In this article, we discuss the logistic, strategic business, regulatory and financial challenges involved in drug-companion diagnostic codevelopment.

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Regional skin hypoplasia has been described in several genetic syndromes, including focal dermal hypoplasia (FDH), microphthalmia with linear skin defects (MLS), oculocerebrocutaneous syndrome (OCCS), and terminal osseous dysplasia and pigmentary defects (TODP). All but OCCS have been reported to follow an X-linked inheritance pattern. We describe a 14-year-old girl with clinical features overlapping with these disorders. She had mild mental retardation, macrocephaly, microphthalmia, right-sided morning glory optic disc anomaly, palmar and lip pits, and polysyndactyly. A swirling pattern of skin hypopigmentation, papular hypopigmented and herniated skin lesions reminiscent of FDH most prominent over her face, head, hands, and feet was evident. Brain magnetic resonance imaging (MRI) showed polymicrogyria (most severely in the perisylvian and mesial frontal regions), enlarged left lateral ventricle, partial agenesis of the corpus callosum, and optic nerve tumor on the right. Dermatopathologic examination of the skin lesions was consistent with basaloid follicular hamartomas. The skin and digit anomalies observed overlap with FDH, but polymicrogyria, basaloid follicular hamartomas, optic nerve tumor, and morning glory anomaly have not previously been described in FDH. Skin defects in MLS are linear and the eyes typically have sclerocornea. Polymicrogyria has been described in OCCS, but not in any of the other three syndromes. The limb anomalies in TODP are reductions rather than polysyndactyly. Skin defects are localized to the face, and digital fibromas usually occur. While significant overlap exists between all four of the syndromes discussed, we believe that the constellation of anomalies observed in this girl most likely comprises a newly recognized syndrome.