Nicolás Pineda

Strong Amerind/White sex bias and a possible sephardic contribution among the founders of a population in Northwest Colombia

Historical and genetic evidences suggest that the recently founded population of Antioquia (Colombia) is potentially useful for the genetic mapping of complex traits. This population was established in the 16th-17th centuries through the admixture of Amerinds, Europeans, and Africans and grew in relative isolation until the late 19th century. To examine the origin of the founders of Antioquia, we typed 11 markers on the nonrecombining portion of the Y chromosome and four markers on mtDNA in a sample of individuals with confirmed Antioquian ancestry. The polymorphisms on the Y chromosome (five biallelic markers and six microsatellites) allow an approximation to the origin of founder men, and those on mtDNA identify the four major founder Native American lineages. These data indicate that approximately 94% of the Y chromosomes are European, 5% are African, and 1% are Amerind. Y-chromosome data are consistent with an origin of founders predominantly in southern Spain but also suggest that a fraction came from northern Iberia and that some possibly had a Sephardic origin. In stark contrast with the Y-chromosome, approximately 90% of the mtDNA gene pool of Antioquia is Amerind, with the frequency of the four Amerind founder lineages being closest to Native Americans currently living in the area. These results indicate a highly asymmetric pattern of mating in early Antioquia, involving mostly immigrant men and local native women. The discordance of our data with blood-group estimates of admixture suggests that the number of founder men was larger than that of women.

An association study of bipolar mood disorder (type I) with the 5-HTTLPR serotonin transporter polymorphism in a human population isolate from Colombia.

The short variant of a functional length polymorphism in the promoter region of the serotonin transporter has been associated with several behavioural and psychiatric traits, including bipolar mood disorder. The same short allele has also been implicated as a modifier of the bipolar phenotype. Here we evaluate the etiologic/modifier role of this polymorphism in a case (N=103) / control (N=112) sample for bipolar mood disorder (type I) collected from an isolated South American population. We did not detect an association between bipolar disorder and the 5-HTT promoter polymorphism in this sample. However, an excess of the short allele was seen in younger cases and in cases with psychotic symptoms. When combined with data from the literature, the increased frequency of the short allele in patients with psychotic symptoms was statistically significant.

Novel cerebrotendinous xanthomatosis mutation causes familial early dementia in Colombia

INTRODUCTION Cerebrotendinous xanthomatosis is an infrequent cause of dementia. It is an autosomal recessive disorder with clinical and molecular heterogeneity. OBJECTIVE To identify the presence of a possible mutation in a Colombian family with several affected siblings and clinical characteristics compatible with cerebrotendinous xanthomatosis associated to early dementia. MATERIALS AND METHODS We studied a series of cases with longitudinal follow-up and genetic analysis. RESULTS These individuals had xanthomas, mental retardation, psychiatric disorders, behavioral changes, and multiple domains cognitive impairment with dysexecutive dominance that progressed to early dementia. CYP27A1 gene coding region sequencing revealed a novel mutation (c.1183_1184insT). CONCLUSION The mutation found in this family is responsible for the described dementia features. Early identification of familial history with mental retardation, xanthomas and cognitive impairment might prevent the progression to this treatable type of dementia. Even though this mutation lies in the most frequently mutated codon of CYP27A1 gene, it has not been reported previously.

Nueva mutación para xantomatosis cerebrotendinosa causa demencia temprana familiar en Colombia

INTRODUCTION Cerebrotendinous xanthomatosis is an infrequent cause of dementia. It is an autosomal recessive disorder with clinical and molecular heterogeneity. OBJECTIVE To identify the presence of a possible mutation in a Colombian family with several affected siblings and clinical characteristics compatible with cerebrotendinous xanthomatosis associated to early dementia. MATERIALS AND METHODS We studied a series of cases with longitudinal follow-up and genetic analysis. RESULTS These individuals had xanthomas, mental retardation, psychiatric disorders, behavioral changes, and multiple domains cognitive impairment with dysexecutive dominance that progressed to early dementia. CYP27A1 gene coding region sequencing revealed a novel mutation (c.1183_1184insT). CONCLUSION The mutation found in this family is responsible for the described dementia features. Early identification of familial history with mental retardation, xanthomas and cognitive impairment might prevent the progression to this treatable type of dementia. Even though this mutation lies in the most frequently mutated codon of CYP27A1 gene, it has not been reported previously.

Características clínicas de los pacientes menores de 18 años con atrofia muscular espinal en Medellín, 2008 - 2013

Introduction: Spinal muscular atrophy (SMA) is a degenerative disease that affects motor neurons in the anterior horn of the spinal cord, it is manifested by progressive muscle weakness predominantly proximal, hypotonia andosteotendinous arreflexia, the cause is a mutation in neuronal survival gene SMN1 Objective: Establish the clinical, electromyographics and genetics characteristics of patients younger than 18 years with spinal muscular atrophy in the Medellin city, during the period 2008-2013. Materials and methods: A retrospective study of patients with SMA seen in the Hospital Universitario San Vicente Foundation and private center of Neuro- pediatric of Medellin during the period 2008-2013 was performed. Data from 29 patientes were available, were reviewed clinical feature, diagnostic aids and treatments practiced. Results: SMA type II resulted the most frequent clinical presentation (62%) followed by SMA type I (24.13%), the main manifestations were hypotonia (100 %), muscle weakness (93.1%) and osteotendinous arreflexia (82.8%), tongue fasciculations occurred in 48.3% of patients. The molecular test was performed in 6 patients and in all the deletion of exon 7 of the SMN1 gene was found. Conclusion: spinal muscular atrophy is a degenerative and progressive disease according to their clinical classification. It should be suspected when there are motoneuronal syndrome and lingual twitches. Molecular diagnosis is the most accurate to confirm the disease.

Alteraciones cognitivas en Parkinson Juvenil causado por la mutación C212Y en el gen Parkin.

In Antioquia, Colombia, four families have been reported with juvenile Parkinson´s disease and carrying the C212Y mutation in the Parkin gene. Many cognitive alterations associated with idiopathic, late-onset Parkinson´s disease have been described; however, little attention has been paid to the description of neuropsychological profiles in families carrying mutations in genes associated with juvenile Parkinson´s disease. For this study we selected a group of ten homozygous carriers of Parkin mutation C212Y with the clinical and a group of molecular diagnosis of Parkinson´s disease, and ten healthy relatives as controls. The neuropsychological evaluation revealed statistically significant differences between the two groups (p < 0.05) in Minimental State Examination and in tests evaluating working memory and attention in which prolonged execution times and marked slowing down of information processing were observed. We suggest that the observed alterations could be considered as neuropsychological features of patients with the C212Y mutation in the Parkin gene, the phenotypic expression of which seems to be associated in this population with slow evolution, mild cognitive impairment and functional involvement.