Hereditary spastic paraparesis presenting as cerebral palsy due to ADD3 variant with mechanistic insight provided by a Drosophila γ-adducin model.

Cerebral palsy (CP) causes neurological disability in early childhood. Hypoxic-ischaemic injury plays a major role in its aetiology, nevertheless, genetic and epigenetic factors may contribute to the clinical presentation. Mutations in ADD3 (encoding γ-adducin) gene have been described in a monogenic form of spastic quadriplegic cerebral palsy (OMIM 601568). We studied a 16-year-old male with spastic diplegia. Several investigations including neurometabolic testing, brain and spine magnetic resonance imaging (MRI) and CGH-Array were normal. Further, clinical genetics assessment and whole exome sequencing (WES) gave the diagnosis. We generated an animal model using Drosophila to study the effects of γ-adducin loss and gain of function. WES revealed a biallelic variant in the ADD3 gene, NM_016824.5(ADD3): c.1100G > A, p.(Gly367Asp). Mutations in this gene have been described as an ultra-rare autosomal recessive, which is a known form of inherited cerebral palsy. Molecular modelling suggests that this mutation leads to a loss of structural integrity of γ-adducin and is therefore expected to result in a decreased level of functional protein. Pan-neuronal over-expression or knock-down of the Drosophila ortholog of ADD3 called hts caused a reduction of life span and impaired locomotion thereby phenocopying aspects of the human disease. Our animal experiments present a starting point to understand the biological processes underpinning the clinical phenotype and pathogenic mechanisms, to gain insights into potential future methods for treating or preventing ADD3 related spastic quadriplegic cerebral palsy.

[Allan-Herndon-Dudley syndrome: a diagnosis to rule out in any male infant with undiagnosed hypotonia]. / Síndrome de Allan-Herndon-Dudley: un diagnóstico a descartar ante todo lactante varón con hipotonía sin causa determinada.

Allan-Herndon-Dudley syndrome is a rare X-linked genetic disorder, caused by a deficiency of the monocarboxylate transporter 8 (MCT8), a specific transporter of thyroid hormones, with functions mainly at the brain level. The syndrome produces an early onset of severe neurological disorder, in which hypotonia predominates. OBJECTIVE: To present a rare case with an unexpected diagnosis, highlighting the usefulness of requesting a complete thyroid profile in every hypotonic male infant without a specific cause. CLINICAL CASE: A 10-month-old male infant with severe axial and peripheral hypotonia, global weakness with little spontaneous mobility, without head support or stable sitting. Complete metabolic and peripheral neurophysiological studies were performed. Genetic studies for spinal muscular atrophy, Prader Willi syndrome, and myotonic dystrophy were also performed. The trio exome analysis detected a probably pathogenic variant c.359C>T;p.(Ser120Phe), hemizygous in exon 1 of the SLC16A2 gene, inherited from the mother. Thyroid abnormalities as increased free triiodothyronine (T3) and thyroid-stimulating hormone (TSH), and delayed myelination were ob served. CONCLUSIONS: MCT8 deficiency should be considered in the case of the male infant with unex plained hypotonia and weakness without a determined cause. The diagnosis is guided by a thyroid profile including free T3 hormone, because it presents a characteristic thyroid profile with decreased free thyroxine (T4), increased free T3, and normal or slightly elevated TSH levels. In this case, the implementation of the trio exome analysis allows establishing an early certain diagnosis.

[Human growth hormone and Turner syndrome]. / Hormona de crecimiento y síndrome de Turner.

OBJECTIVE: The evaluation of clinical and analytical parameters as predictors of the final growth response in Turner syndrome patients treated with growth hormone. MATERIAL AND METHODS: A retrospective study was performed on 25 girls with Turner syndrome (17 treated with growth hormone), followed-up until adult height. Auxological, analytical, genetic and pharmacological parameters were collected. A descriptive and analytical study was conducted to evaluate short (12 months) and long term response to treatment with growth hormone. RESULTS: A favourable treatment response was shown during the first year of treatment in terms of height velocity gain in 66.6% of cases (height-gain velocity >3cm/year). A favourable long-term treatment response was also observed in terms of adult height, which increased by 42.82±21.23cm (1.25±0.76 SDS), with an adult height gain of 9.59±5.39cm (1.68±1.51 SDS). CONCLUSIONS: Predictors of good response to growth hormone treatment are: A) initial growth hormone dose, B) time on growth hormone treatment until starting oestrogen therapy, C) increased IGF1 and IGFBP-3 levels in the first year of treatment, and D) height gain velocity in the first year of treatment.