RESUMO
OBJECTIVE: To study school achievement in grade 9 of compulsory school in children with congenital hypothyroidism (CH), both those detected by the national screening program and those with a normal screening result and thus diagnosed later. STUDY DESIGN: Nationwide study of children in the Swedish Medical Birth Register (n = 1â547â927) from 1982 through 1997, linked to the neonatal screening CH cohort and the National School Register. Dried blood spot (DBS) samples are collected from all newborn infants, according to the neonatal screening program. Thyroid-stimulating hormone was used for CH screening. CH was defined as either having an abnormal screening result (DBS+) and treatment with levothyroxine (LT4+) or having a normal screening result but a CH diagnosis in the National Patient Register and treatment with LT4 (DBS-/ICD+/LT4+). Regression models were used to study school performance, which as measured as grade point sum and national test results. Sibling analysis also was performed to account for unmeasured familial factors. RESULTS: There were 448 children who were DBS+/LT4+ and 475 children who were DBS-/ICD+/LT4+. Children with CH had lower grade point sum, adjusted ß = - 6.34 (95% CI -11.7 to -1.01) and adjusted ß = -10.3 (95% CI -15.5 to -5.20) for those with abnormal (DBS+/LT4+) and normal screening (DBS-/ICD+/LT4+) results, respectively. CH also was associated with lower result on the national tests, especially in mathematics. These associations remained in the sibling analyses. CONCLUSIONS: Youth with CH had slightly lower school achievements compared with those without CH and compared with their siblings. CH children with a normal screening result, and thus diagnosed later, presented the lowest results on grade point sum and national tests.
RESUMO
OBJECTIVES: To evaluate the clinical symptoms and biochemical findings and establish the genetic etiology in a cohort of pediatric patients with combined deficiencies of the mitochondrial respiratory chain complexes. STUDY DESIGN: Clinical and biochemical data were collected from 55 children. All patients were subjected to sequence analysis of the entire mitochondrial genome, except when the causative mutations had been identified based on the clinical picture. Whole exome sequencing/whole genome sequencing (WES/WGS) was performed in 32 patients. RESULTS: Onset of disease was generally early in life (median age, 6 weeks). The most common symptoms were muscle weakness, hypotonia, and developmental delay/intellectual disability. Nonneurologic symptoms were frequent. Disease causing mutations were found in 20 different nuclear genes, and 7 patients had mutations in mitochondrial DNA. Causative variants were found in 18 of the 32 patients subjected to WES/WGS. Interestingly, many patients had low levels of coenzyme Q10 in muscle, irrespective of genetic cause. CONCLUSIONS: Children with combined enzyme defects display a diversity of clinical symptoms with varying age of presentation. We established the genetic diagnosis in 35 of the 55 patients (64%). The high diagnostic yield was achieved by the introduction of massive parallel sequencing, which also revealed novel genes and enabled elucidation of new disease mechanisms.