Isovaleric aciduria identified by newborn screening: Strategies to predict disease severity and stratify treatment.

Newborn screening (NBS) allows early identification of individuals with rare disease, such as isovaleric aciduria (IVA). Reliable early prediction of disease severity of positively screened individuals with IVA is needed to guide therapeutic decision, prevent life-threatening neonatal disease manifestation in classic IVA and over-medicalization in attenuated IVA that may remain asymptomatic. We analyzed 84 individuals (median age at last study visit 8.5 years) with confirmed IVA identified by NBS between 1998 and 2018 who participated in the national, observational, multicenter study. Screening results, additional metabolic parameters, genotypes, and clinical phenotypic data were included. Individuals with metabolic decompensation showed a higher median isovalerylcarnitine (C5) concentration in the first NBS sample (10.6 vs. 2.7 µmol/L; p < 0.0001) and initial urinary isovalerylglycine concentration (1750 vs. 180 mmol/mol creatinine; p = 0.0003) than those who remained asymptomatic. C5 was in trend inversely correlated with full IQ (R = -0.255; slope = -0.869; p = 0.0870) and was lower for the "attenuated" variants compared to classic genotypes [median (IQR; range): 2.6 µmol/L (2.1-4.0; 0.7-6.4) versus 10.3 µmol/L (7.4-13.1; 4.3-21.7); N = 73]. In-silico prediction scores (M-CAP, MetaSVM, and MetaLR) correlated highly with isovalerylglycine and ratios of C5 to free carnitine and acetylcarnitine, but not sufficiently with clinical endpoints. The results of the first NBS sample and biochemical confirmatory testing are reliable early predictors of the clinical course of IVA, facilitating case definition (attenuated versus classic IVA). Prediction of attenuated IVA is supported by the genotype. On this basis, a reasonable algorithm has been established for neonates with a positive NBS result for IVA, with the aim of providing the necessary treatment immediately, but whenever possible, adjusting the treatment to the individual severity of the disease.

Astrogenesis in the murine dentate gyrus is a life-long and dynamic process.

Astrocytes are highly abundant in the mammalian brain, and their functions are of vital importance for all aspects of development, adaption, and aging of the central nervous system (CNS). Mounting evidence indicates the important contributions of astrocytes to a wide range of neuropathies. Still, our understanding of astrocyte development significantly lags behind that of other CNS cells. We here combine immunohistochemical approaches with genetic fate-mapping, behavioural paradigms, single-cell transcriptomics, and in vivo two-photon imaging, to comprehensively assess the generation and the proliferation of astrocytes in the dentate gyrus (DG) across the life span of a mouse. Astrogenesis in the DG is initiated by radial glia-like neural stem cells giving rise to locally dividing astrocytes that enlarge the astrocyte compartment in an outside-in-pattern. Also in the adult DG, the vast majority of astrogenesis is mediated through the proliferation of local astrocytes. Interestingly, locally dividing astrocytes were able to adapt their proliferation to environmental and behavioral stimuli revealing an unexpected plasticity. Our study establishes astrocytes as enduring plastic elements in DG circuits, implicating a vital contribution of astrocyte dynamics to hippocampal plasticity.

Semen quality and testicular adrenal rest tumour development in 46,XY congenital adrenal hyperplasia: the importance of optimal hormonal replacement.

OBJECTIVE: To study the impact of the quality of therapeutic control on fertility and on the prevalence of testicular adrenal rest tumours (TART) in young males with congenital adrenal hyperplasia (CAH). DESIGN: Combined cross-sectional and retrospective clinical study. METHODS: Twenty-nine patients and age-matched controls underwent clinical investigation, including semen analysis, testicular and adrenal ultrasound imaging, and serum and hair steroid analysis. The quality of therapeutic control was categorized as 'poor', 'moderate' or 'medium'. Evaluation of current control was based on concentrations of 17-hydroxy-progesterone and androstenedione in serum and 3 cm hair; previous control was categorized based on serum 17-hydroxy-progesterone concentrations during childhood and puberty, anthropometric and puberty data, bone age data and adrenal sizes. RESULTS: Semen quality was similar in males with CAH and controls (P = 0.066), however patients with 'poor' past control and large TART, or with 'poor' current CAH control had low sperm counts. Follicle-stimulating hormone was decreased, if current CAH control was 'poor' (1.8 ± 0.9 U/L; 'good': 3.9 ± 2.2 U/L); P = 0.015); luteinizing hormone was decreased if it was 'poor' (1.8 ± 0.9 U/L; P = 0.041) or 'moderate' (1.9 ± 0.6 U/L; 'good': 3.0 ± 1.3 U/L; P = 0.025). None of the males with 'good' past CAH control, 50% of those with 'moderate' past control and 80% with 'poor past control had bilateral TART. The prevalence of TART in males with severe (class null or A) CYP21A2 mutations was 53% and 25% and 0% in those with milder class B and C mutations, respectively. CONCLUSIONS: TART development is favoured by inadequate long-term hormonal control in CAH. Reduced semen quality may be associated with large TART. Gonadotropin suppression by adrenal androgen excess during the latest spermatogenic cycle may contribute to impairment of spermatogenesis.

Newborn screening and disease variants predict neurological outcome in isovaleric aciduria.

Isovaleric aciduria (IVA), a metabolic disease with severe (classic IVA) or attenuated phenotype (mild IVA), is included in newborn screening (NBS) programs worldwide. The long-term clinical benefit of screened individuals, however, is still rarely investigated. A national, prospective, observational, multi-center study of individuals with confirmed IVA identified by NBS between 1998 and 2018 was conducted. Long-term clinical outcomes of 94 individuals with IVA were evaluated, representing 73.4% (for classic IVA: 92.3%) of the German NBS cohort. In classic IVA (N = 24), NBS prevented untimely death except in one individual with lethal neonatal sepsis (3.8%) but did not completely prevent single (N = 10) or recurrent (N = 7) metabolic decompensations, 13 of them occurring already neonatally. IQ (mean ± SD, 90.7 ± 10.1) was mostly normal but below the reference population (P = .0022) and was even lower in individuals with severe neonatal decompensations (IQ 78.8 ± 7.1) compared to those without crises (IQ 94.7 ± 7.5; P = .01). Similar results were obtained for school placement. In contrast, individuals with mild IVA had excellent neurocognitive outcomes (IQ 105.5 ± 15.8; normal school placement) and a benign disease course (no metabolic decompensation, normal hospitalization rate), which did not appear to be impacted by metabolic maintenance therapy. In conclusion, NBS reduces mortality in classic IVA, but does not reliably protect against severe neonatal metabolic decompensations, crucial for favorable neurocognitive outcome. In contrast, individuals with mild IVA had excellent clinical outcomes regardless of metabolic maintenance therapy, questioning their benefit from NBS. Harmonized stratified therapeutic concepts are urgently needed.

Growth and Final Height Among Children With Phenylketonuria.

BACKGROUND AND OBJECTIVES: Growth is an important criterion to evaluate health in childhood and adolescence, especially in patients depending on special dietary treatment. Phenylketonuria (PKU) is the most common inherited disease of amino acid metabolism. Patients with PKU depend on a special phenylalanine-restricted diet, low in natural protein. The study aimed to evaluate growth, growth rate, and target height in 224 patients with PKU. METHODS: Retrospective, longitudinal analysis of standardized, yearly measurements of height, weight, and calculated growth rate (SD score [SDS]) of patients with PKU aged 0 to 18 years were conducted by using the national computerized CrescNet database. Inclusion was restricted to patients carried to term with a confirmed diagnosis of PKU or mild hyperphenylalaninemia determined by newborn screening and early treatment initiation. RESULTS: From birth to adulthood, patients with PKU were significantly shorter than healthy German children (height SDS at 18 years: -0.882 ± 0.108, P < .001). They missed their target height by 3 cm by adulthood (women: P = .02) and 5 cm (men: P = .01). In patients receiving casein hydrolysate during childhood, this was more pronounced compared with patients receiving amino acid mixtures (P < .001). Growth rate was significantly reduced during their first 2 years of life and in puberty (growth rate SDS: -1.1 to -0.5 m/year, P < .001 and -0.5; P < .02). CONCLUSIONS: Early diagnosed, treated, and continuously monitored patients with PKU showed reduced height from birth onward. During the last 2 decades, this phenomenon attenuated, probably because of advances in PKU therapy related to protein supplements and special low-protein foods.

Low-level hyperinsulinism with hypoglycemic spells in an infant with mosaic Turner syndrome and mild Kabuki-like phenotype: a case report and review of the literature.

BACKGROUND: Impaired glucose tolerance and type 2 diabetes are well-known features in patients with Turner syndrome. To the best of our knowledge, there is only one reported case of hyperinsulinemic hypoglycemia associated with a complex mosaic Turner syndrome available in the current literature. PATIENT: We report on the case of a 13-month-old girl with a complex mosaic Turner genotype and mild hyperinsulinemic hypoglycemia responsive to diazoxide therapy. RESULTS: Cytogenetic analyses showed two or possibly three cell lines. Sixty percent of the cell lines had a 45,X genotype and the rest had 46,XX with a marker ring chromosome. Diagnosis of a mosaic Turner syndrome and mild Kabuki-like phenotype was confirmed. CONCLUSIONS: Despite the rareness of this case, clinicians should be aware of the possibility of hyperinsulinemic hypoglycemia in patients with Turner syndrome to prevent further brain damage caused by hypoglycemic episodes and seizures. Although the mechanism leading to hyperinsulinism in this condition is still unknown, the present report discusses this rare presentation and gives an overview on the current literature regarding this case.

Transition of young adults with phenylketonuria from pediatric to adult care.

BACKGROUND: Transition from pediatric to adult health care is a particularly vulnerable period for patients with inborn metabolic diseases. Aim of the present study was to evaluate the current transition situation of patients with phenylketonuria (PKU) in Leipzig, Germany, by analysis of the medical care, metabolic control, patients' satisfaction, socio-economic and psychosocial status, in order to identify areas of weakness and potential improvement. METHODS: Patients who had been transferred from pediatric to adult medical care between 2005 and 2008 were identified. An interview was performed using a questionnaire. Pediatric case notes and the present physician's case notes were analyzed retrospectively. Socio-demographic data were compared to data derived from the annual statistics of the city of Leipzig, Germany in 2008. RESULTS: seventy two transferred patients were identified and included in the study, 48 patients responded to the questionnaire, the data of 24 non-responders were analysed retrospectively. About 90% of the responding patients with PKU were satisfied with the current transition situation. However, they agreed to several suggestions of improvement. Most specifically an interdisciplinary appointment before the definite transfer to the adult clinics was asked for. At the time of transition, most of the patients were in good metabolic control according to current treatment guidelines (median dried blood phenylalanine concentration 853 µmol/l before versus 690 µmol/l after transition). Of the interviewed patients 92% were still on a low phenylalanine diet in combination with the intake of a phenylalanine free amino acid mixture. Of the interviewees 77% carried a secondary school certificate or a secondary modern school qualification, but only 19% had achieved senior high school diploma (controls 38.2%). Marital status was comparable with the population of Leipzig. However, fewer patients with PKU had children (15% versus 37%). CONCLUSION: Transition of patients with PKU from pediatric to adult care seems to be successful in Leipzig. Patients were mostly satisfied with the transition situation. Still, some suggestions for improvements appeared to be desirable. During transition medical care and metabolic control were stable. However, with regard to psychosocial and socioeconomic data differences to the control population were detected.

Deletion and point mutations of PTHLH cause brachydactyly type E.

Autosomal-dominant brachydactyly type E (BDE) is a congenital limb malformation characterized by small hands and feet predominantly as a result of shortened metacarpals and metatarsals. In a large pedigree with BDE, short stature, and learning disabilities, we detected a microdeletion of approximately 900 kb encompassing PTHLH, the gene coding for parathyroid hormone related protein (PTHRP). PTHRP is known to regulate the balance between chondrocyte proliferation and the onset of hypertrophic differentiation during endochondral bone development. Inactivation of Pthrp in mice results in short-limbed dwarfism because of premature differentiation of chondrocyte. On the basis of our initial finding, we tested further individuals with BDE and short stature for mutations in PTHLH. We identified two missense (L44P and L60P), a nonstop (X178WextX( *)54), and a nonsense (K120X) mutation. The missense mutation L60P was tested in chicken micromass culture with the replication-competent avian sarcoma leukosis virus retroviral expression system and was shown to result in a loss of function. Thus, loss-of-function mutations in PTHLH cause BDE with short stature.

A case of maternal PKU syndrome despite intensive patient counseling.

We report on a 21-year-old woman with classic phenylketonuria, who presented at our outpatient clinic at week 14 of pregnancy. Despite intensive preconceptional counselling about the risk of raised Phenylalanine (Phe) levels for the offspring and nutritional consultations about the necessity to be on a Phe-restricted diet she had elevated blood Phe concentrations. Phe level could be lowered to the recommended range during a stay as an inpatient, but the patient was not able to maintain the recommended levels due to non-compliance. The patient delivered a newborn with classic maternal PKU syndrome (microcephaly, brachygnathia, congenital heart defect and psychomotoric retardation), which is nowadays rarely seen under preconceptional Phe-restricted diet. With more PKU patients reaching the childbearing age, intensive preconception counselling about maternal PKU syndrome is of pivotal importance for the women. However, a major factor in preventing Phe embryopathy is patient compliance in keeping the diet, which was insufficient in the case presented.

Three novel missense mutations within the LHX4 gene are associated with variable pituitary hormone deficiencies.

CONTEXT: The LHX4 LIM-homeodomain transcription factor has essential roles in pituitary gland and nervous system development. Heterozygous mutations in LHX4 are associated with combined pituitary hormone deficiency. OBJECTIVES: Our objectives were to determine the nature and frequency of LHX4 mutations in patients with pituitary hormone deficiency and to examine the functional outcomes of observed mutations. DESIGN: The LHX4 gene sequence was determined from patient DNA. The biochemical and gene regulatory properties of aberrant LHX4 proteins were characterized using structural predictions, pituitary gene transcription assays, and DNA binding experiments. PATIENTS: A total of 253 patients from 245 pedigrees with GH deficiency and deficiency of at least one additional pituitary hormone was included in the study. RESULTS: In five patients, three types of heterozygous missense mutations in LHX4 that result in substitution of conserved amino acids were identified. One substitution is between the LIM domains (R84C); the others are in the homeodomain (L190R; A210P). The patients have GH deficiency; some also display reductions in TSH, LH, FSH, or ACTH, and aberrant pituitary morphology. Structural models predict that the aberrant L190R and A210P LHX4 proteins would have impaired DNA binding and gene activation properties. Consistent with these models, EMSAs and transfection experiments using pituitary gene promoters demonstrate that whereas the R84C form has reduced activity, the L190R and A210P proteins are inactive. CONCLUSIONS: LHX4 mutations are a relatively rare cause of combined pituitary hormone deficiency. This report extends the range of phenotypes associated with LHX4 gene mutations and describes three novel exonic mutations in the gene.

Roles of the LHX3 and LHX4 LIM-homeodomain factors in pituitary development.

The LHX3 and LHX4 LIM-homeodomain transcription factors play essential roles in pituitary gland and nervous system development. Mutations in the genes encoding these regulatory proteins are associated with combined hormone deficiency diseases in humans and animal models. Patients with these diseases have complex syndromes involving short stature, and reproductive and metabolic disorders. Analyses of the features of these diseases and the biochemical properties of the LHX3 and LHX4 proteins will facilitate a better understanding of the molecular pathways that regulate the development of the specialized hormone-secreting cells of the mammalian anterior pituitary gland.

Thirteen novel mutations in the NR0B1 (DAX1) gene as cause of adrenal hypoplasia congenita.

X-linked adrenal hypoplasia congenita (AHC) is a rare developmental disorder associated with primary adrenal insufficiency and combined primary and secondary male hypogonadism. It is caused by deletions or mutations of the NR0B1 (DAX1) gene encoding DAX1, an atypical orphan member of the nuclear receptor superfamily. The continuous molecular genetic analysis of male patients with primary adrenal insufficiency revealed 13 novel mutations within the coding region of the NR0B1 gene which are predicted to inactivate the DAX1 function. These were three nonsense mutations (c.312C>A, p.Cys104X, c.670C>T, p.Gln224X; and c.873G>A, p.Trp291X), five duplications (c.269_270dup, c.421_422dup, c.895_896dup, c.989dup, c.999_1000dup), and five deletions (c.483del, c.745_746del, c.734_740del, c.1092del, and c.1346del). All of the mutations resulted in a premature stop codon destroying the ligand binding domain of the predictive DAX1 protein.

PROP1 mutations cause progressive deterioration of anterior pituitary function including adrenal insufficiency: a longitudinal analysis.

Mutations in the PROP1 gene are the most frequent genetic defects in patients with combined pituitary hormone insufficiency. However, controversy exists about the timing and extent of pituitary insufficiency, and it remains unclear whether adrenal failure is a typical feature of this condition. We performed a retrospective longitudinal analysis of nine patients with PROP1 mutations who were under medical supervision at our clinic for 15.7 +/- 3.4 yr. All patients initially presented with growth failure (height sd score, -3.7 +/- 0.3) at a mean age of 4.9 +/- 0.8 yr. They were first diagnosed with GH and TSH deficiency, and replacement therapy was instituted at 6.1 +/- 1.1 and 6.8 +/- 1.2 yr, respectively. All seven patients who reached pubertal age required sex hormone substitution at 15.0 +/- 0.7 yr. Repeated functional testing of the anterior pituitary axes revealed a progressive decline with age in peak levels of GH, TSH, prolactin, and LH/FSH. All patients developed at least partial adrenal insufficiency, with a gradual decline of the function of the pituitary adrenal axis and eventually required substitution with hydrocortisone at a mean age of 18.4 +/- 3.5 yr. It is concluded that anterior pituitary function in patients with PROP1 mutations deteriorates progressively and includes adrenal insufficiency as a feature of this condition, which has important clinical relevance in childhood and adolescence.