SEARCH · Search PubMed

Results for “Homozygote”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

4 recordsLinked to original sources

PubMed2026

The Homozygous p.(Arg215Ter) Variant in XRCC2 Is Associated With Atypical Fanconi Anemia Without Major Hematological Abnormalities in Childhood.

Fanconi Anemia (FA) is the most frequent inherited bone marrow failure syndrome. A role for the XRCC2 gene in FA was suspected in 2012 and confirmed in 2016, but only two affected individuals have been described thus far, and no long-term follow-up is available. Here we present two young related adults born to consanguineous parents, in whom we identified the homozygous p.(Arg215Ter) variant in XRCC2. Both patients presented with mild intellectual disability, microcephaly, distinctive facial features, short stature, thumb abnormalities, and abnormal skin pigmentation. Unlike in FA, DEB test resulted negative in peripheral blood during childhood and no cytopenia, clonal evolution, or other hematological complications were detected until the age of 19 and 20 years, respectively. Our report suggests that the homozygous p.(Arg215Ter) variant in XRRC2 causes a distinctive FA-like disorder, characterized by the typical physical characteristics seen in FA, but a lack of major hematological manifestations in childhood, and the presence of a more pronounced neurodevelopmental phenotype than that seen in FA.

Humans↗

PubMed2026

Histidine Supplementation Stabilizes Hearing and Vision and Improves Growth in HARS1-Related Autosomal Recessive Disorder Associated With Usher-Like Symptoms.

Autosomal recessive HARS1-related disorder (originally described as Usher syndrome type 3B) caused by a homozygous Y454S variant in the histidyl-tRNA synthetase gene (HARS1) is characterized by progressive sensorineural hearing and vision loss and respiratory deterioration with risk for sudden death following febrile illnesses. In-vitro studies have previously shown that histidine can rescue a humanized yeast model for pathogenic HARS alleles. Fourteen children homozygous for HARS Y454S were treated with supplemental oral histidine (50 mg/kg BID) and monitored with bloodwork and physical, visual, and audiometry assessments during a 3-year clinical trial, then followed for more than 4 years on histidine in the post-trial period. Patient fibroblasts were assessed for response to histidine. Hearing and vision remained stable, and growth improved significantly. Children remained healthy, with no severe deteriorations despite exposure to bacterial and viral infections, including COVID-19. Gains in growth were maintained in the post-trial period on varying levels of histidine supplementation. Daily oral histidine supplementation in children with autosomal recessive HARS1-related disorder can ameliorate or slow the progression of disease and is safe, inexpensive, and well tolerated. This study adds to the growing list of autosomal recessive ARSopathies (aminoacyl-tRNA synthetase disorders) that are amenable to amino acid supplementation.

Humans↗

PubMed2026

Integrated genomic and biochemical diagnosis of a novel homozygous start-loss variant in AKR1D1 associated with neonatal cholestasis.

INTRODUCTION: Congenital bile acid synthesis defects are rare autosomal recessive disorders that typically present in early infancy with cholestasis, progressive liver dysfunction, and, in severe cases, acute liver failure. These conditions may mimic other metabolic diseases detected in newborn screening, complicating early diagnosis. The AKR1D1 gene encodes Δ4-3-oxosteroid 5β-reductase, a key enzyme in primary bile acid synthesis, and pathogenic variants cause bile acid synthesis defect type 2 (OMIM #235555). CASE DESCRIPTION: We report a 3-month-old male infant with severe neonatal cholestasis and a history of elevated tyrosine levels in newborn screening. Pregnancy was high risk and unmonitored, with birth outside a hospital. Parental consanguinity was first-degree. Early metabolic evaluation showed transient normalization of tyrosine levels, but subsequent analyses revealed recurrent hyper-tyrosinemia. Urinary organic acids showed increased 4-hydroxyphenyl metabolites, with absent succinylacetone, excluding tyrosinemia type I. Progressive cholestasis developed, accompanied by coagulopathy, hyperbilirubinemia, hyperammonemia, and markedly elevated alpha-fetoprotein. Imaging revealed no structural liver abnormalities. Clinical exome sequencing identified a novel homozygous start-loss variant in AKR1D1, likely abolishing functional enzyme production. Metabolic studies confirmed increased urinary excretion of 3-oxocholenoic acids consistent with abnormal bile acid synthesis and supporting a diagnosis of bile acid synthesis defect type 2. Oral cholic acid therapy led to stabilization and improvement in clinical and biochemical parameters. DISCUSSION/CONCLUSION: This case illustrates the diagnostic complexity of neonatal cholestasis, particularly when initial metabolic findings suggest alternative etiologies. It highlights the importance of newborn screening as a tool for broader diagnostic suspicion and the critical role of early molecular diagnosis and multidisciplinary care. Timely recognition and targeted therapy can improve outcomes, prevent liver transplantation, and enable accurate genetic counseling, especially in consanguineous families.

Humans↗

PubMed2026

Investigating telomere length and hTERT-MNS16A VNTR polymorphism in Bipolar disorder: Insights into clinical features.

OBJECTIVE: To compare leukocyte telomere length (LTL; T/S ratio) and hTERT-MNS16A VNTR polymorphism between patients with bipolar disorder (BD) and healthy controls, and to examine their associations with clinical features in BD. METHODS: A total of 179 participants (100 BD patients, 79 healthy controls) were enrolled. Relative LTL was assessed by qPCR-based T/S ratio; hTERT-MNS16A VNTR genotyping by PCR and gel electrophoresis. Clinical variables including episode frequency, illness duration, age at onset, symptom severity scales, first episode polarity, and family history of mood disorder were evaluated. RESULTS: No significant differences were observed between BD patients and healthy controls in T/S ratio or hTERT-MNS16A VNTR genotype distributions (all p > 0.05). Within the BD group, S allele carriers (L/S or S/S) had significantly more depressive episodes than L/L homozygotes (1.45 ± 2.58 vs. 0.61 ± 1.52; p = .040). Significant inverse correlations were identified between T/S ratio and depressive episode count (ρ = -0.220, p = .028) and total mood episodes (ρ = -0.207, p = .039). Multivariable negative binomial regression revealed four independent predictors of depressive episode frequency: lower T/S ratio (p = 0.005), S allele carriage (L/S or S/S genotypes) (p = 0.001), first depressive episode polarity (p < 0.001), and family history of mood disorder (p = 0.035). CONCLUSION: Although LTL and hTERT-MNS16A VNTR genotype did not differ between BD patients and healthy controls, shorter telomere length and S allele carriage were independently associated with higher depressive episode frequency within the BD group, implicating telomere biology and hTERT genetic variation in the biological substrate of depressive illness burden.

Humans↗