De Sanctis-Cacchione syndrome: A case report and literature review

Persistent TFIIH binding to non-excised DNA damage causes cell and developmental failure

Congenital nucleotide excision repair (NER) deficiency gives rise to several cancer-prone and/or progeroid disorders. It is not understood how defects in the same DNA repair pathway cause different disease features and severity. Here, we show that the absence of functional ERCC1-XPF or XPG endonucleases leads to stable and prolonged binding of the transcription/DNA repair factor TFIIH to DNA damage, which correlates with disease severity and induces senescence features in human cells. In vivo, in C. elegans, this prolonged TFIIH binding to non-excised DNA damage causes developmental arrest and neuronal dysfunction, in a manner dependent on transcription-coupled NER. NER factors XPA and TTDA both promote stable TFIIH DNA binding and their depletion therefore suppresses these severe phenotypical consequences. These results identify stalled NER intermediates as pathogenic to cell functionality and organismal development, which can in part explain why mutations in XPF or XPG cause different disease features than mutations in XPA or TTDA.

De Sanctis-Cacchione Syndrome with Subdural Effusion: A Rare Case from India with Review of Literature

De Sanctis-Cacchione syndrome (DCS) formerly known as xerodermic idiocy is characterised by cutaneous photosensitivity, microcephaly, mental retardation, short stature, hypogonadism, spasticity, peripheral neuropathy and sensorineural deafness. Here in, we present the case of a four and half years old male child with features of severe acute malnutrition (SAM) with a typical bird like facies and sunken eyes who had history of photosensitive pruritic pigmentary skin lesions on sun exposed areas from a very early age of six months. Gross developmental delay, ataxia, microcephaly, short stature, hypogonadism and cachectic wasting were identified on examination and hypertransaminasemia and hypothyroidism were recorded from biochemical profile. Subsequent visual evoked response and brainstem evoked response audiometry revealed anterior visual pathway dysfunction and bilateral profound sensorineural hearing loss. Magnetic resonance imaging of brain yielded subdural effusion with mass effect in addition to cerebro-cerebral atrophy and demyelination. Skin biopsy further detected dysplastic changes and early signs of squamous cell carcinoma (SCC). Although few cases are reported sporadically throughout the world, to our best of knowledge till date only 11 such cases have been reported completely in Indian medical literature which makes our case report the 12th one with distinctive novel association of subdural effusion.

Xeroderma Pigmentosum: Gene Variants and Splice Variants

The nucleotide excision repair (NER) is essential for the repair of ultraviolet (UV)-induced DNA damage, such as cyclobutane pyrimidine dimers (CPDs) and 6,4-pyrimidine-pyrimidone dimers (6,4-PPs). Alterations in genes of the NER can lead to DNA damage repair disorders such as Xeroderma pigmentosum (XP). XP is a rare autosomal recessive genetic disorder associated with UV-sensitivity and early onset of skin cancer. Recently, extensive research has been conducted on the functional relevance of splice variants and their relation to cancer. Here, we focus on the functional relevance of alternative splice variants of XP genes.

Extra-anogenital giant cutaneous squamous cell carcinomas require multidisciplinary management

Cutaneous squamous cell carcinoma (cSCC) is a highly prevalent cancer and the majority of cSCC have a good prognosis. However, a subset of cSCC can progress to advanced disease. We present the first reported case of a giant cSCC located on the breast. In addition, a systematic literature search on extra-anogenital giant (EAG) cSCC was performed using Pubmed and MEDLINE databases. Thirty-one articles could be retained which were relevant for this review. A total of 42 well-described cases were identified. Median age at presentation was 70 years (range 9-100 years). Twenty-four (57%) patients were male, eighteen were female (43%). The estimated median delay of treatment was 12 months (range 1 to >240 months). In 27 patients (64%) the giant cSCC was localized on the neck, face or scalp, 6 on the thoracic wall or back (14%), 4 on the lower limb (10%), 2 on the hip or buttock (5%), 2 on the upper limb (5%), one (2%) on the breast. Tumor stage at presentation was T2, T3 and T4 in respectively 26 (62%), 11 (26%) and 5 (12%) cases. Lymph node metastases were identified in 1 patient (2%) and distant metastases in another patient (2%). In 34 out of 42 cases (81%) primary radical surgical excision was performed, 3 received radiotherapy, 2 chemotherapy and 3 palliative care. In the cases with reported follow-up, four patients (4/30: 13%) died of disease. The treatment of EAG cSCC poses many problems, making a multidisciplinary approach of paramount importance.

Embryology, Malformations, and Rare Diseases of the Cochlea

Despite the low overall prevalence of individual rare diseases, cochlear dysfunction leading to hearing loss represents a symptom in a large proportion. The aim of this work was to provide a clear overview of rare cochlear diseases, taking into account the embryonic development of the cochlea and the systematic presentation of the different disorders. Although rapid biotechnological and bioinformatic advances may facilitate the diagnosis of a rare disease, an interdisciplinary exchange is often required to raise the suspicion of a rare disease. It is important to recognize that the phenotype of rare inner ear diseases can vary greatly not only in non-syndromic but also in syndromic hearing disorders. Finally, it becomes clear that the phenotype of the individual rare diseases cannot be determined exclusively by classical genetics even in monogenetic disorders.

Repair protein persistence at DNA lesions characterizes XPF defect with Cockayne syndrome features

The structure-specific ERCC1-XPF endonuclease plays a key role in DNA damage excision by nucleotide excision repair (NER) and interstrand crosslink repair. Mutations in this complex can either cause xeroderma pigmentosum (XP) or XP combined with Cockayne syndrome (XPCS-complex) or Fanconi anemia. However, most patients carry compound heterozygous mutations, which confounds the dissection of the phenotypic consequences for each of the identified XPF alleles. Here, we analyzed the functional impact of individual pathogenic XPF alleles on NER. We show that XP-causing mutations diminish XPF recruitment to DNA damage and only mildly affect global genome NER. In contrast, an XPCS-complex-specific mutation causes persistent recruitment of XPF and the upstream core NER machinery to DNA damage and severely impairs both global genome and transcription-coupled NER. Remarkably, persistence of NER factors at DNA damage appears to be a common feature of XPCS-complex cells, suggesting that this could be a determining factor contributing to the development of additional developmental and/or neurodegenerative features in XP patients.

Diseases Associated with Mutation of Replication and Repair Proteins

Alterations in proteins that function in DNA replication and repair have been implicated in the development of human diseases including cancer, premature ageing, skeletal disorders, mental retardation, microcephaly, and neurodegeneration. Drosophila has orthologues of most human replication and repair proteins and high conservation of the relevant cellular pathways, thus providing a versatile system in which to study how these pathways are corrupted leading to the diseased state. In this chapter I will briefly review the diseases associated with defects in replication and repair proteins and discuss how past and future studies on the Drosophila orthologues of such proteins can contribute to the dissection of the mechanisms involved in disease development.