Genetic diagnostic approach to intellectual disability and multiple congenital anomalies in Indonesia.

Intellectual disability (ID) and multiple congenital anomalies (MCA) are major contributors to infant mortality, childhood morbidity, and long-term disability, with multifactorial aetiology including genetics. We aim to set a diagnostic approach for genetic evaluation of patients with ID and MCA, which can be applied efficiently with a good diagnostic rate in Indonesia or other low resources settings. Out of 131 ID cases, twenty-three individuals with ID/global developmental delay (GDD) and MCA were selected from two-steps of dysmorphology screening and evaluation. Genetic analysis included chromosomal microarray (CMA) analysis, targeted panel gene sequencing, and exome sequencing (ES). CMA revealed conclusive results for seven individuals. Meanwhile, two out of four cases were diagnosed by targeted gene sequencing. Five out of seven individuals were diagnosed using ES testing. Based on the experience, a novel and comprehensive flowchart combining thorough physical and dysmorphology evaluation, followed by suitable genetic tests is proposed as a diagnostic approach to elucidate the genetic factor(s) of ID/GDD and MCA in low resources settings such as Indonesia.

Clinical manifestation and genetic analysis of familial rare disease genodermatosis xeroderma pigmentosum.

Xeroderma pigmentosum (XP) is a rare autosomal recessive disease characterized by hypersensitivity of the skin to ultraviolet radiation and other carcinogenic agents. This ailment is characterized by increased photosensitivity, skin xerosis, early skin aging, actinic keratosis, erythematous lesions, and hyperpigmentation macules. In this serial case report, we presented four cases with XP from two families in Indonesia. Both families were referred from rural referral health centers, and each family has two affected siblings. They had freckle-like pigmentation on the face, trunk, and extremities, which progressed since childhood. One patient of family 2 died because of an infectious disease. Histopathological examination using cytokeratine (CK), CD10, and Ber-EP4 staining from available tissue biopsy of one affected case of family 1 identified basal cell carcinoma (BCC) on the cheek and melanoma on the right eye. Mutation analysis found ERCC2, c2047C>T and XPC, c1941T>A in the first and second families, respectively. We suppose that this is the first case report of XP in Indonesia that incorporates clinical examination, genetic analysis, and extensive histopathological examination, including immunohistochemistry staining, and a novel pathogenic variant of XPC was found in the second family.

Surveillance and prevalence of fragile X syndrome in Indonesia.

Fragile X syndrome (FXS) is the most prevalent inherited cause of intellectual disability (ID) and autism spectrum disorder (ASD). Many studies have been conducted over the years, however, in Indonesia there is relatively less knowledge on the prevalence of FXS. We reviewed all studies involving FXS screening and cascade testing of the high-risk population in Indonesia for two decades, to elucidate the prevalence, as well as explore the presence of genetic clusters of FXS in Indonesia. The prevalence of FXS in the ID population of Indonesia ranged between 0.9-1.9%, while in the ASD population, the percentage was higher (6.15%). A screening and cascade testing conducted in a small village on Java Island showed a high prevalence of 45% in the ID population, suggesting a genetic cluster. The common ancestry of all affected individuals was suggestive of a founder effect in the region. Routine screening and subsequent cascade testing are essential, especially in cases of ID and ASD of unknown etiology in Indonesia.

Repeat expansion and methylation-sensitive triplet-primed polymerase chain reaction for fragile X mental retardation 1 gene screening in institutionalised intellectually disabled individuals.

INTRODUCTION: Fragile X syndrome (FXS) is the most prevalent X-linked intellectual disability (ID) and a leading genetic cause of autism, characterised by cognitive and behavioural impairments. The hyperexpansion of a CGG repeat in the fragile X mental retardation 1 (FMR1) gene leads to abnormal hypermethylation, resulting in the lack or absence of its protein. Tools for establishing the diagnosis of FXS have been extensively developed, including assays based on triplet-primed polymerase chain reaction (TP-PCR) for detection and quantification of the CGG trinucleotide repeat expansion, as well as determination of the methylation status of the alleles. This study aimed to utilise a simple, quick and affordable method for high sensitivity and specificity screening and diagnosis of FXS in institutionalised individuals with ID. METHODS: A total of 109 institutionalised individuals at the Center for Social Rehabilitation of Intellectual Disability Kartini, Temanggung, Central Java, Indonesia, were screened in a three-step process using FastFrax™ Identification, Sizing and Methylation Status Kits. RESULTS: Two samples that were classified as indeterminate with respect to the 41-repeat control at the identification step were subsequently determined to be non-expanded by both sizing and methylation status analyses. Two samples classified as expanded at the identification step were determined to carry full mutation expansions > 200 repeats that were fully methylated using sizing and methylation status analyses, respectively, yielding a disease prevalence of 1.83%. CONCLUSION: Repeat expansion and methylation-specific TP-PCR is practical, effective and inexpensive for the diagnosis of FXS, especially in high-risk populations of individuals with ID of undetermined aetiology.

Pathogenic variant in NFIX gene affecting three sisters due to paternal mosaicism.

We present a family with three girls presenting similar dysmorphic features, including overgrowth, intellectual disability, macrocephaly, prominent forehead, midface retrusion, strabismus, and scoliosis. Both parents were unaffected, suggesting the presence of an autosomal recessive syndrome. Following exome sequencing, a heterozygous nonsense variant was identified in the NFIX gene in all three siblings. The father appeared to have a low-grade (7%) mosaicism for this variant in his blood. Previously, de novo pathogenic variants in NFIX have been identified in Marshall-Smith syndrome and Malan syndrome, which share distinctive phenotypic features shared with the patients of the present family. This case emphasizes the importance of further molecular analysis especially in familial cases, to exclude the possibility of parental mosaicism.

Duplication of 1q31.3q41 in two affected siblings due to paternal insertional translocation.

We report two sisters with developmental delay and dysmorphic features, as well as a history of seizures. Both sisters have short stature, microcephaly and shared facial dysmorphisms. We detected an 18.1 Mb interstitial gain in 1q31.3q41 and a 140 kb interstitial loss in 7p11.2 in both siblings by using array analysis in the older sister and copy number variation analysis in whole exome sequencing data in the younger sister. We further examined parental chromosomes and found an insertional translocation in the unaffected father, having a 46,XY,ins(7;1)(p11.2;q31.3q41) karyotype. A 1.8 Mb loss at the rearranged 1q segment was subsequently detected on additional array analysis in the father, as well as the 140 kb loss in 7p11.2. We describe the clinical consequences of the 18.1 Mb duplication of the long arm of chromosome 1 due to an unbalanced paternal insertional translocation and compare these with the clinical phenotypes of patients with an overlapping 1q duplication.