Variable developmental delays and characteristic facial features-A novel 7p22.3p22.2 microdeletion syndrome?

7p22.2 Microduplication: A Pathogenic CNV?

Partial duplication of the short arm of chromosome 7 is a rare chromosome rearrangement. The phenotype spectrum associated with this rearrangement is extremely variable even if in the last decade the use of high-resolution microarray technology for the investigation of patients carrying this rearrangement allowed for the identification of the 7p22.1 sub-band causative of this phenotype and to recognize the corresponding 7p22.1 microduplication syndrome. We report two unrelated patients that carry a microduplication involving the 7.22.2 sub-band. Unlike 7p22.1 microduplication carriers, both patients only show a neurodevelopmental disorder without malformations. We better characterized the clinical pictures of these two patients providing insight into the clinical phenotype associated with the microduplication of the 7p22.2 sub-band and support for a possible role of this sub-band in the 7p22 microduplication syndrome.

The tweety Gene Family: From Embryo to Disease

The tweety genes encode gated chloride channels that are found in animals, plants, and even simple eukaryotes, signifying their deep evolutionary origin. In vertebrates, the tweety gene family is highly conserved and consists of three members—ttyh1, ttyh2, and ttyh3—that are important for the regulation of cell volume. While research has elucidated potential physiological functions of ttyh1 in neural stem cell maintenance, proliferation, and filopodia formation during neural development, the roles of ttyh2 and ttyh3 are less characterized, though their expression patterns during embryonic and fetal development suggest potential roles in the development of a wide range of tissues including a role in the immune system in response to pathogen-associated molecules. Additionally, members of the tweety gene family have been implicated in various pathologies including cancers, particularly pediatric brain tumors, and neurodegenerative diseases such as Alzheimer’s and Parkinson’s disease. Here, we review the current state of research using information from published articles and open-source databases on the tweety gene family with regard to its structure, evolution, expression during development and adulthood, biochemical and cellular functions, and role in human disease. We also identify promising areas for further research to advance our understanding of this important, yet still understudied, family of genes.

Cerebral folate transporter deficiency syndrome in three siblings: Why genetic testing for developmental and epileptic encephalopathies should be performed early and include the FOLR1 gene

Cerebral folate transporter deficiency syndrome, caused by FOLR-1 mutations is characterized by late infantile onset, severe developmental regression, epilepsy, and leukodystrophy. An extremely low concentration of 5-methyltetrahydrofolate in the cerebrospinal fluid provides a crucial clue to its diagnosis and is a treatment target. Oral or intravenous folinic acid (5-formyltetrahydrofolate) administration improves clinical symptoms and brain magnetic resonance imaging (MRI) findings. We describe three siblings carrying a novel homozygous FOLR1 nonsense mutation, that were referred due to intractable epilepsy and progressive neurological decline. Brain MRI showed hypomyelination and cerebellar atrophy. Folinic acid (oral and intravenous) supplementation, initiated after over 15 years illness, has failed to result in any sizeable clinical or neurophysiological improvement. Cerebral folate transport deficiency bears overlapping clinical features with many severe developmental encephalopathies. It is crucial to recognize FOLR1 signs and establish an early clinical and molecular diagnosis in order to provide timely folinic acid treatment and improve outcome.

Partial trisomy 16q and partial monosomy 7p of a fetus derivated from paternal balanced translocation: A case report

INTRODUCTION

Subchromosomal deletions and duplications could currently be detected by noninvasive preliminary screening (NIPS). However, NIPS is a screening test that requires further diagnosis. Here we report a fetus with an autosomal abnormality revealed by NIPS and conventional karyotype combined with copy number variations sequencing (CNV-seq) confirmed the fetus with an unbalanced translocation.

PATIENT CONCERN

This was the fourth pregnancy of a 30-year-old woman who underwent 2 spontaneous abortions and gave birth to a child with a normal phenotype. The woman and her husband were healthy and nonconsanguineous. NIPS indicated a repeat of about 19-Mb fragment at the region of 16q22.1-q22.4 at 17-week gestation.

DIAGNOSES

The combination of traditional karyotype and CNV-seq could better locate the abnormal chromosomal region and further identify the source of fetal chromosomal abnormalities. Simultaneously, we evaluated the fetal morphology by ultrasound examination. The karyotype of the fetus was 46,XX,der(7)t(7;16)(p22;q23) and CNV-seq results showed an approximately 20.96-Mb duplication in 16q22.1-q24.3 (69200001-90160000) and an approximately 3.86-Mb deletion in 7p22.3-p22.2 (40001-3900000). Prenatal ultrasound revealed the fetal micrognathia. The paternal karyotype was 46,XY, t (7;16) (p22;q23), while the maternal was normal. The fetus inherited an abnormal chromosome 7 from its father.

INTERVENTIONS

No treatment for the fetus.

OUTCOMES

Pregnancy was terminated.

CONCLUSIONS

To our knowledge, the occurrence of de novo partial trisomy 16q (16q22.1-qter) and partial monosomy 7p (7p22.2-pter) has not previously been reported up to now. Here, we present the perinatal findings of such a case and a review of the literatures. CNV-seq combined with karyotype is a useful tool for chromosomal abnormalities indicated by NIPS.

Neurodevelopmental Impairment As the Main Phenotypic Hallmark Associated with the Translocation t(7;10)(7p22.3;q26.11)

Reported here is a novel patient carrying an unbalanced t (10q26.11-q26.3; 7p22.3) and presenting with a severe intellectual disability with autistic features, abnormalities of muscle tone, and a drug-responsive epilepsy. The prominence of neurological and neurodevelopmental abnormalities in the clinical phenotype highlights a possible pathogenic role for different genes in the involved regions. Hypothetical mechanisms may include a possible gene dosage effect for DOCK1 and/or haploinsufficiency of PRKAR1B SUN1, ADAP1 , and GPER1 .

Small 7p22.3 microdeletion: Case report of Snx8 haploinsufficiency and neurological findings

Some cases of chromosome 7p22.3 deletions have been reported, but the genotype-phenotype correlation is still uncertain. Neurodevelopmental delay and heart anomalies have been recorded as the most recurrent defects. We describe the clinical features of a four-year-old male child with a 139 kb deletion at 7p22.3 involving SNX8 gene, inherited from a mosaic mother. The same deletion is also present in the fetus on the ongoing third pregnancy of the couple with normal fetal ultrasound assessment. The proband was prenatally diagnosed with left kidney agenesis. He does not show any congenital heart disease, but mild intellectual disability, learning and language delay, and severe behavioral problems related to the hyperactive-impulsive and inattentive area. These clinical features are also evident in other 7p22 deletions cases involving the SNX8 gene, supporting the role of this gene in neurodevelopment. Conversely, the revision of all published cases with small 7p22 deletions and the absence of heart malformations in the present family confirm that this region is involved in heart development, anyway did not confirm the role of SNX8 in cardiac phenotypes, either due to the reduced penetrance or the involvement of other candidate genes.

Deletion of chr7p22 and chr15q11: Two Familial Cases of Immune Deficiency: Extending the Phenotype Toward Dysimmunity

Background: We report here two new familial cases of associated del15q11 and del7p22, with the latter underlining the clinical variability of this deletion. Two siblings patients presented a similar familial imbalanced translocation, originating from a balanced maternal translocation, with deletions of 7p22 and of 15q11 [arr[GRCh37] 7p22.3-p22.2(42976-3736851)x1, 15q11.1-q11.2(20172544-24979427)x1]. Methods: We used aCGH array, FISH, and karyotype for studying the phenotype of the two patients. Results: The 7p22 deletion (3.5 Mb) contained 58 genes, including several OMIM genes. Patients 1 and 2 exhibited acquisition delays, morphological particularities, and hypogammaglobulinemia, which was more severe in patient 1. Patient 1 presented also with cerebral vasculitis. Conclusion: We discuss here how the PDGFa, CARD11, LFNG, GPER1, and MAFK genes, included in the deletion 7p22, could be involved in the clinical and biological features of the two patients.