Biallelic mutations in the TTC5 gene have been associated with autosomal recessive intellectual disability (ARID) and subsequently with an ID syndrome including severe speech impairment, cerebral atrophy, and hypotonia as clinical cornerstones. A TTC5 role in IDs has been proposed based on the physical interaction of TTC5 with p300, and possibly reducing p300 co‐activator complex activity, similarly to what was observed in Menke‐Hennekam 1 and 2 patients (MKHK1 and 2) carrying, respectively, mutations in exon 30 and 31 of CREBBP and EP300, which code for the TTC5‐binding region. Recently, TTC5‐related brain malformation has been linked to tubulinopathies due to the function of TTC5 in tubulins' dynamics. We reported seven new patients with novel or recurrent TTC5 variants. The deep characterization of the molecular and phenotypic spectrum confirmed TTC5‐related disorder as a recognizable, very severe neurodevelopmental syndrome. In addition, other relevant clinical aspects, including a severe pre‐ and postnatal growth retardation, cryptorchidism, and epilepsy, have emerged from the reversal phenotype approach and the review of already published TTC5 cases. Microcephaly and facial dysmorphism resulted in being less variable than that documented before. The TTC5 clinical features have been compared with MKHK1 published cases in the hypothesis that clinical overlap in some characteristics of the two conditions was related to the common p300 molecular pathway.

Background: Loeys-Dietz syndrome (LDS) is a rare connective tissue disorder characterized by cardiovascular manifestations, especially aortic dilatations and arterial tortuosity, craniofacial and skeletal features, joint laxity or contractures, skin abnormalities, hypotonia and motor delay. Its diagnosis is established by the identification of a pathogenic variant in TGFBR1, TGFBR2, SMAD2, SMAD3, TGFB2 or TGFB3 genes. In newborns and toddlers, vascular complications such as aneurism rupture, aortic dissection, and intracerebral incidents, can occur already in the weeks of life. To avoid these events, it is crucial to precociously identify this condition and to start an apunderwent a surgical procedurepropriate treatment which, depending on the severity of the vascular involvement, might be medical or surgical. Case presentation: We report two cases of Loeys-Dietz syndrome precociously diagnosed. The first describes a male, born at 38 + 1 weeks of gestation, with hypotonia, joint hypermobility, arachnodactyly, and fingers joint contractures, as well as senile appearance and facial dysmorphisms. In the suspect of a connective tissue disorder, an echocardiography was performed and revealed an aortic root dilatation of 13 mm (Z score + 3). A trio based Whole Exome Sequencing found a novel de novo variant in the TGFBR2 gene. Despite the onset of a low-dose angiotensin receptor blocker therapy, the aneurysm progressed. The second case describes a female, born at 41 + 3 weeks of gestation. During the neonatal examination a cleft palate was noticed, as well as minor dysmorphisms. Since the family history was suspicious for connective tissue disorders, a genetic panel was performed and identified a pathogenetic variant in TGFB3 gene. In this case, the echocardiography revealed no abnormalities. Conclusions: In addition to our cases, we identified 14 subjects with neonatal LDS in the medical literature. All of them had aortic involvement. Skeletal and face abnormalities, including eyes and palate malformations, were also highly frequent. Overall, 10 subjects required medical therapy to avoid aneurysm progression, and 8 patients underwent surgical procedures. Benefits of an early diagnosis of LDS are various and imply a potential modification of the natural history of the disease with early interventions on its complications.

To date, little is known about the role of olfactory receptor (OR) genes on smell performance. Thanks to the availability of whole-genome sequencing data of 802 samples, we identified 41 knockout (KO) OR genes (i.e., carriers of Loss of Function variants) and evaluated their effect on odor discrimination in 218 Italian individuals through recursive partitioning analysis. Furthermore, we checked the expression of these genes in human and mouse tissues using publicly available data and the presence of organ-related diseases in human KO (HKO) individuals for OR expressed in non-olfactory tissues (Fisher test). The recursive partitioning analysis showed that age and the high number (burden) of OR-KO genes impact the worsening of odor discrimination (p-value < 0.05). Human expression data showed that 33/41 OR genes are expressed in the olfactory system (OS) and 27 in other tissues. Sixty putative mouse homologs of the 41 humans ORs have been identified, 58 of which are expressed in the OS and 37 in other tissues. No association between OR-KO individuals and pathologies has been detected. In conclusion, our work highlights the role of the burden of OR-KO genes in worse odor discrimination.

Background: Cerebro-oculo-facio-skeletal syndrome (COFS) is a severe and progressive neurologic condition characterized by prenatal onset of arthrogryposis, cataract, microcephaly and growth failure. The aim of this study was to present a case of recurrence of the COFS syndrome and to propose a differential diagnosis flow-chart in case of prenatal findings of arthrogryposis and cataract. Case presentation: We report a case of recurrence of COFS3 syndrome within the same family, with similar diagnostic features. In the first case the COFS syndrome remained undiagnosed, while in the second case, due to prenatal findings of arthrogryposis and cataract, genetic investigation focusing on responsible genes of COFS (ERCC5, ERCC6 and FKTN genes) was carried out. The fetus was found to be compound heterozygous for two different ERCC5 mutations, confirming the clinical suspect of COFS syndrome. A review of the literature on possible causative genes of prenatal cataract and arthrogryposis was performed and we present a flow-chart to guide differential diagnosis and possible genetic testing in case of these findings. Conclusion: COFS syndrome is a rare autosomic recessive condition. However, it can be suspected and diagnosed prenatally. The flow-chart illustrates a pathway to guide differential diagnosis according to the prenatal findings. Main syndromes, key testing and specific genes are included. Targeted molecular testing should be offered to the couple in order to reach a diagnosis and assess the recurrence risk for future pregnancies.

Glycosylphosphatidylinositol (GPI) biosynthesis defect 11 (GPIBD11), part of the heterogeneous group of congenital disorders of glycosylation, is caused by biallelic pathogenic variants in PIGW. This rare disorder has previously been described in only 12 patients. We report four novel patients: two sib fetuses with congenital anomalies affecting several organs, including the heart; a living girl with tetralogy of Fallot, global developmental delay, behavioral abnormalities, and atypic electroencephalography (EEG) without epilepsy; a girl with early-onset, treatment-resistant seizures, developmental regression, and recurrent infections, that ultimately passed away prematurely due to pneumonia. We also illustrate evolving facial appearance and biochemical abnormalities. We identify two novel genotypes and the first frameshift variant, supporting a loss-of-function pathogenic mechanism. By merging our cohort with patients documented in the literature, we deeply analyzed the clinical and genetic features of 16 patients with PIGW-related disorder, revealing a severe multisystemic condition deserving complex management and with uncertain long-term prognosis. We consider the role of PIGW within the critical 17q12 region, which is already associated with genomic disorders caused by deletion or duplication and characterized by variable expressivity. Finally, we discuss PIGW dosage effects and a second hit hypothesis in human development and disease.