Snyder-Robinson syndrome (SRS, OMIM 309583) is a rare X-linked syndrome characterized by mental retardation, marfanoid habitus, skeletal defects, osteoporosis and facial asymmetry. Linkage analysis localized the related gene to Xp21.3-p22.12, and a G-to-A transition at point +5 of intron 4 of the spermine synthase gene, which caused truncation of the SMS protein and loss of enzyme activity, was identified in the original family. Here we describe another family with Snyder-Robinson syndrome in two Mexican brothers and a novel mutation (c.496T>G) in the exon 5 of the SMS gene confirming its involvement in this rare X-linked mental retardation syndrome.

Three female patients with Cantu syndrome were studied, two of whom were adults presenting with the complication of lymphoedema, as described earlier in a male patient with this syndrome. The aim of this study is to report the clinical characteristics of these three new cases and to emphasize that lymphoedema, as observed in two of the patients described here, has been observed in 11.5% of patients with Cantu syndrome and that heterochromia iridis, observed in one patient, is probably a new feature of this condition.

The spinocerebellar ataxia type 2 is a neurodegenerative disease with autosomal dominant inheritance; clinically characterized by progressive cerebellar ataxia, slow ocular saccades, nystagmus, ophthalmoplegia, dysarthria, dysphagia, cognitive deterioration, mild dementia, peripheral neuropathy. Infantile onset is a rare presentation that only has been reported in four instances in the literature. In the present work a boy aged 5 years 7 months was studied due to horizontal gaze-evoked nystagmus, without saccades, ataxic gait, dysarthria, dysphagia, dysmetria, generalized spasticity mainly pelvic, bilateral Babinsky. The mother aged 27 years-old presented progressive cerebellar ataxia, dysarthria, dysmetria, dysdiadochokinesis, limb ataxia and olivopontocerebellar atrophy. The molecular analysis was made by identifying the expansion repeats in tandem by long PCR to analyze the repeats in the ATXN2 gene. We found an extreme CAG expansion repeats of~884 repeats in the child. We describe a Mexican child affected by SCA2 with an infantile onset, associated with a high number of CAG repeats previously no reported and anticipation phenomenon.

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Amyotrophic lateral sclerosis (ALS) is a lethal, progressive neurodegenerative disease that affects upper and lower motor neurons. [1][2] Its prevalence in Mexico ranges from 5000 to 7000 patients according to Martínez et al. In France, it is estimated at 2.5 per 100,000 population. 3 The age of onset is approximately 47.5 years, with survival of up to 58.9 months after diagnosis. Otero et al. reported that ALS accounts for more than 90 % of cases of motor neuron diseases in Mexico, with the phenotype including signs of upper or lower motor neuron. 1