High frequency of SH3TC2 mutations in Czech HMSN I patients

La??uthová P, Mazanec R, Vondrá?ek P, ?i?ková D, Haberlová J, Sabová J, Seeman P. High frequency of SH3TC2 mutations in Czech HMSN I patients. Charcot–Marie–Tooth (CMT) neuropathy type 4C (CMT4C) is an autosomal recessive (AR), demyelinating neuropathy with early spine deformities caused by mutations in the SH3TC2 gene. To determine the spectrum of SH3TC2 mutations in the Czech population, the entire coding region of SH3TC2 was sequenced in 60 unrelated Czech patients. The prevalent mutation was shown to be the p.Arg954Stop. Therefore, 412 additional patients referred for CMT testing were tested for the presence of p.Arg954Stop only. Of 60 patients in whom the SH3TC2 gene was sequenced, at least one mutation was detected in 13 (21.7%) patients and biallelic pathogenic mutations were detected in 7 (11.6%) patients. Of the 412 patients tested for p.Arg954Stop, the mutation was found in 8 patients (1.94%), 6 were homozygous and 2 were heterozygous. The second causative mutation was detected by sequencing in one of the patients but not in the other. Nine novel sequence variants were detected. Their pathogenicity was further tested in silico and in control samples. Mutations in the SH3TC2 gene are a frequent cause of demyelinating hereditary neuropathy among Czech patients. In total, at least one mutation was found in 21 unrelated patients. CMT4C seems to be the most frequent type of AR CMT and one of the most frequent of all CMT types. Mutation p.Arg954Stop is highly prevalent in the Czech population. Patients with demyelinating neuropathy along with non‐dominant mode of inheritance and negative for CMT1A/hereditary neuropathy with liability to pressure palsy should be tested for the presence of the p.Arg954Stop mutation or other mutations in the SH3TC2 gene.     

Clinical,In Silico,and Experimental Evidence for Pathogenicity of Two Novel Splice Site Mutations in the SH3TC2 Gene

Abstract: Charcot-Marie-Tooth (CMT) neuropathy is the most common inherited neuromuscular disorder. CMT is genetically very heterogeneous. Mutations in the SH3TC2 gene cause Charcot-Marie-Tooth neuropathy type 4C (CMT4C), a demyelinating form with autosomal recessive inheritance. In this study, two novel splice site mutations in the SH3TC2 gene have been studied (c.279G → A, c.3676–8G → A). Mutation c.279G → A was detected on one allele in two unrelated families with CMT4C in combination with a known pathogenic mutation (c.2860 C →T in one family, c.505T → C in the other) on the second allele of SH3TC2 gene. Variant c.3676–8G → A was detected in two patients from unrelated families on one allele of the SH3TC2 gene in combination with c.2860C →T mutation on the other allele. Several in silico tests were performed and exon trap experiments were undertaken in order to prove the effect of both mutations on proper splicing of SH3TC2. Fragments of SH3TC2 were subcloned into pET01 exon trap vector (Mobitec) and transfected into COS-7 cells. Aberrant splicing was predicted in silico for both mutations, which was confirmed by exon trap analysis. For c.279G → A mutation, 19 bases from intron 3 are retained in cDNA. The mutation c.3676–8G→ A produces a novel splice acceptor site for exon 17 and complex changes in splicing were observed. We present evidence that mutations c.279G → A and c.3676–8G →A in the SH3TC2 gene cause aberrant splicing and are therefore pathogenic and causal for CMT4C.     

SH3GL2基因在人脑胶质瘤中表达的研究

目的研究SH3GL2基因的表达改变与人脑胶质瘤之间的相关性。方法选择42例人脑胶质瘤和26例正常人脑组织标本,应用荧光定量PCR和Western blot方法检测标本中SH3GL2基因mRNA和蛋白的表达情况。结果与正常脑组织标本相比,SH3GL2基因在人脑胶质瘤组织标本中的mRNA和蛋白的表达存在明显下调,结果具有统计学差异(0.05)。结论SH3GL2基因的表达改变与人脑胶质瘤相关,是一个新的候选的肿瘤抑制基因。P     

SH2B3基因标签单核苷酸多态性与汉族原发性高血压的关系

目的探讨SH2B衔接蛋白3(SH2B3)基因标签单核苷酸多态(SNPs)与汉族原发性高血压(EH)的关系。方法用聚合酶链式反应-限制性片段长度多态性方法(PCR-RFLP),对1 020例汉族人(EH患者和对照者各510例)SH2B3基因6个标签SNPs(rs7309325、rs11065898、rs10849947、rs2239196、rs2238154和rs739496)的多态性进行检测,运用遗传模型分析该基因与汉族EH的相关性。结果 rs2239196位点基因型和等位基因在EH组和对照组间的频率分布均具有显著性差异(Bonfferoni校正P0.05),Logistic回归分析结果显示T等位基因携带者的患病风险显著升高(OR=2.59,95%CI 1.36~4.96,Bonfferoni校正P0.05)。结论 SH2B3基因rs2239196位点T等位基因可能是汉族EH发生的危险因子。     

A novel mutation in the GDAP1 gene is associated with autosomal recessive Charcot-Marie-Tooth disease in an Amish family

Charcot–Marie–Tooth disease (CMT) constitutes a large group of genetically heterogeneous disorders of the peripheral nervous system. Autosomal recessive forms of CMT are less common in the general population but account for the vast majority of CMT phenotypes in communities with a high prevalence of consanguinity. At least 10 genetic loci cause autosomal recessive forms of CMT. Mutations in the ganglioside-induced differentiation-associated protein 1 ( GDAP1 ) gene are among the most frequent genetic causes of autosomal recessive forms of CMT. To date, 28 mutations in GDAP1 gene have been linked with the disease. Here, we report a novel GDAP1 mutation in an Old Order Amish family with CMT. To ascertain the Amish CMT locus, we performed a genome-wide single nucleotide polymorphism (SNP) analysis on one of three patients from a consanguineous pedigree. Assuming mutation homogeneity, the analysis sought large homozygous SNP blocks that also contained known CMT loci. The largest homozygous SNP block in the patient was localized to chromosome 8q13.1-21.3 and contained the GDAP1 gene. Sequence analysis revealed a novel homozygous mutation, c.692C>T, at codon 231 (p.P231L) in exon 5 of GDAP1 in all patients. Neither the unaffected individuals in the family nor the healthy control samples were homozygous for this mutation. Our findings suggested that this novel mutation in GDAP1 gene is associated with an autosomal recessive form of CMT in Ohio Old Order Amish community.     

A recurrent loss-of-function alanyl-tRNA synthetase (AARS) mutation in patients with Charcot-Marie-Tooth disease type 2N (CMT2N)

Charcot-Marie-Tooth (CMT) disease comprises a heterogeneous group of peripheral neuropathies characterized by muscle weakness and wasting, and impaired sensation in the extremities. Four genes encoding an aminoacyl-tRNA synthetase (ARS) have been implicated in CMT disease. ARSs are ubiquitously expressed, essential enzymes that ligate amino acids to cognate tRNA molecules. Recently, a p.Arg329His variant in the alanyl-tRNA synthetase (AARS) gene was found to segregate with dominant axonal CMT type 2N (CMT2N) in two French families; however, the functional consequence of this mutation has not been determined. To investigate the role of AARS in CMT, we performed a mutation screen of the AARS gene in patients with peripheral neuropathy. Our results showed that p.Arg329His AARS also segregated with CMT disease in a large Australian family. Aminoacylation and yeast viability assays showed that p.Arg329His AARS severely reduces enzyme activity. Genotyping analysis indicated that this mutation arose on three distinct haplotypes, and the results of bisulfite sequencing suggested that methylation-mediated deamination of a CpG dinucleotide gives rise to the recurrent p.Arg329His AARS mutation. Together, our data suggest that impaired tRNA charging plays a role in the molecular pathology of CMT2N, and that patients with CMT should be directly tested for the p.Arg329His AARS mutation.     

A c.3216_3217delGA mutation in AGL gene in Tunisian patients with a glycogen storage disease type III: evidence of a founder effect

Mili A, Ben Charfeddine I, Amara A, MamaÏ O, Adala L, Ben Lazereg T, Bougulia J, Saad A, Limem K, Gribaa M. A c.3216_3217delGA mutation in AGL gene in Tunisian patients with a glycogen storage disease type III: evidence of a founder effect. Glycogen storage disease type III (GSD III) is an autosomal recessive disorder characterized by excessive accumulation of abnormal glycogen in the liver and muscles and caused by deficiency in the glycogen debranching enzyme, the amylo‐1,6‐glucosidase (AGL). In this study, we report the clinical, biochemical and genotyping features of five unrelated GSD III patients coming from the same region in Tunisia. The concentration of erythrocyte glycogen and AGL activity were measured by colorimetric and fluorimetric methods, respectively. Four CA/TG microsatellite markers flanking the AGL gene in chromosome 1 were amplified with fluoresceinated primers. The full coding exons and their relevant exon–intron boundaries of the AGL gene were directly sequenced for the patients and their parents. All patients showed a striking increase of erythrocytes glycogen content. No AGL activity was detected in peripheral leukocytes. Sequencing of the AGL gene identified a c.3216_3217delGA (p.Glu1072AspfsX36) mutation in the five patients which leads to a premature termination, abolishing the AGL activity. Haplotype analysis showed that the mutation was associated with a common homozygote haplotype. Our results suggested the existence of a founder effect responsible for GSD III in this region of Tunisia.     

The mutation p.D313Y is associated with organ manifestation in Fabry disease

Fabry disease (FD) is a multisystem lysosomal storage disorder caused by mutations in the GLA gene. The clinical significance of the mutation p.D313Y is still under debate. Retrospective chart analysis of clinical (neurological, cardiac, renal, and ophthalmological), genetic, and biochemical (lyso‐globotriaosylsphingosine, lyso‐Gb3; enzyme activity) data was performed in all our patients carrying the p.D313Y mutation. Fourteen patients from 5 families (10 female, 4 male; age range 10‐51) were included. Symptoms and organ manifestations compatible with FD could be identified in 10 patients. Cerebrovascular events occurred in 4 females. Seven patients reported pain or acroparaesthesia. Cornea verticillata was found in 1 patient, mild retinal vascular tortuosity in 5 patients. Lyso‐Gb3 was elevated in 2 females with cerebrovascular involvement. Classical cardiac, renal or skin manifestations could not be identified. The mutation p.D313Y in the GLA gene may lead to organ manifestations and elevation of the Fabry‐specific biomarker lyso‐Gb3. Neurological symptoms (stroke and pain) and ocular manifestations seem to be the leading findings. Annual routine visits are recommended for patients carrying the p.D313Y mutation. Enzyme replacement therapy might be considered in symptomatic patients.     

Glucose-6-phosphatase gene (727G→T) splicing mutation is prevalent in Hong Kong Chinese patients with glycogen storage disease type la

Glycogen storage disease type la (GSD1a) is an autosomal recessive metabolic disorder caused by a deficiency in glucose-6-phosphatase (GóPase). We analyzed the GóPase genes of two unrelated Chinese families with GSD1a. DNA sequencing of all five exons and the exonintron boundaries revealed a G → T transversion at nucleotide 727 (727G→T) in exon 5, which has previously been reported to cause abnormal splicing. In one family, the subject and her affected sister were confirmed to be homozygous for this mutation and their parents to be heterozygotes. In the other family, the proband was identified to be heterozygous for this mutation, and a novel mutation, the 341delG in exon 2, was identified. This mutation alters the reading frame and creates a stop codon TAA 15 codons downstream from the mutation, resulting in a truncated protein. Family studies revealed that the father was heterozygous for the 727G → T mutation and that the mother was heterozygous for the 341delG mutation. This is the first time that the 727G→T mutation has been found in Chinese patients or outside Japan. Since we only tested two GSDla families and found 727G→T in both, we believe that this mutation may also be prevalent in our local Chinese population. To investigate allele frequencies, we screened 385 Chinese healthy volunteers and found two asymptomatic carriers. Our findings suggest that the 727G → T mutation is indeed prevalent in Hong Kong.     

PPP1R3基因3′端非翻译区5 bp缺失/插入多态性与2型糖尿病相关性研究

目的　研究 1型蛋白磷酸酶骨骼肌特异糖原靶向调节亚单位 (PPP1R3)基因 3′-非翻译区 5 bp缺失 /插入 (deletion/insertion,D/I)多态性与 2型糖尿病 (type 2 diabetes,T2 DM)的相关性。方法　选取安徽省合肥地区汉族 T2 DM患者 2 6 8例 ,正常对照 10 6名 ,用聚合酶链反应扩增片段长度多态性技术进行基因型测定。结果　 (1) PPP1R3基因 3′-非翻译区 5 bp D/I多态性的基因型及等位基因频率在 T2 DM与正常对照组间分布差异无显著性 (P>0 .0 5 )。(2 ) T2 DM或正常对照组中不同基因型间发病年龄、病程、空腹血糖、餐后 2 h血糖、空腹胰岛素、胰岛素敏感指数、体重指数、腰臀围比、收缩压、舒张压差异均无显著性 (P>0 .0 5 )。(3) PPP1R3基因 3′-非翻译区 5 bp D/I多态性频率与日本人群和加拿大人群相近。明显低于 Pima印第安人、瑞典的白人。结论　 PPP1R3基因 3′-非翻译区 5 bp D/I多态性与安徽省合肥地区 2型糖尿病发病无明显关联 ,具有明显的种族差异。     

PPP1R3基因多态性与中国汉族人群2型糖尿病的相关性研究

目的　旨在研究 1型蛋白磷酸酶骨骼肌特异的糖原靶向调节亚单位基因 (PPP1R3)Asp90 5Tyr以及 3′ -UTR5bpD/I多态性与安徽省汉人群的 2型糖尿病 (T2DM )相关性。方法　运用PCR -RFLP法对安徽省合肥地区 36 6例汉族受试者 (T2DM患者 2 6 2例 ,健康成人 10 4例 )进行基因型测定。结果　 (1)PPP1R3基因Asp90 5Tyr以及 3′ -UTR 5bpD/I多态性的基因型及等位基因频率在T2DM与健康对照组间分布均没有显著性差异 (P >0 .0 5 )。 (2 )PPP1R3基因Asp90 5Tyr以及3′ -UTR 5bpD/I多态性间呈连锁不平衡 ,其分布频率在不同人群中不尽相同。结论　PPP1R3基因Asp90 5Tyr以及 3′ -UTR 5bpD/I多态性可能在安徽省合肥地区 2型糖尿病发病中不起重要作用。两种多态性的分布表现明显的种族性。     

The alpha-2 macroglobulin gene is not associated with Alzheimer's disease in a case-control sample

Genetic association has recently been reported between alleles in the alpha-2-macroglobulin (A2M) gene and the occurrence of Alzheimer's disease (AD) in familial and sporadic samples. We have investigated the A2M intronic deletion polymorphism in a case-control study of 295 unrelated clinic and community-based AD cases, and compared these to a sample of 113 unrelated control individuals recruited as part of an epidemiological study. Our results show no association between A2M and AD in either case sample. Furthermore, A2M is not predictive of AD in an interactive fashion when considering APOE, race or gender. In a subset of our larger sample we have also investigated the A2M Val1000Ile polymorphism, and again find no evidence for association. We conclude that there is no genetic association between A2M and AD in our case-control sample.     

Hunter disease in a girl caused by R468Q mutation in the iduronate-2-sulfatase gene and skewed inactivation of the X chromosome carrying the normal allele

Hunter disease is an X-linked recessive mucopolysaccharide storage disorder caused by iduronate-2-sulfatase deficiency and is rare in females. We describe here findings in a girl with Hunter disease of the severe type. She had a normal karyotype but a marked deficiency of iduronate-2-sulfatase activity in lymphocytes and cultured fibroblasts. In a sequence analysis of the iduronate-2-sulfatase gene, evidence was obtained for the R468Q (G¹⁴⁰³ to A) mutation, a common one in Hunter disease. RT-PCR showed her cDNA to represent only the R468Q allele, although at the genomic level she was a heterozygote with one normal allele. Her brother had the R468Q mutation, and their mother was a carrier of this mutation. The fusion products of CHO (TG^R,Neo^R) with patient's fibroblasts cultured in HAT/G418 selective medium, carried only the maternal allele. However, in genomic DNA from the patient's fibroblasts, only the paternal allele of the androgen receptor gene, a gene subjected to differential methylation of the inactive X-chromosome, was methylated. These findings strongly suggest that the severe form of Hunter disease in this girl was the result of selective expression of the maternal allele carrying the missense mutation R468Q, which in turn resulted from skewed X inactivation of the paternal nonmutant X chromosome. Hum Mutat 10:361–367, 1997. © 1997 Wiley-Liss, Inc.     

Homozygous mutation (A228T) in the 5α-reductase type 2 gene in a boy with 5α-reductase deficiency: Genotype–phenotype correlations

The molecular basis of a patient with 5α-reductase deficiency was investigated in this study. This disease is a rare form of male pseudohermaphroditism with virilization during puberty. The child was raised as a girl, but had a male gender identity early in life. The diagnosis was set at the age of 13 years when the virilization process began. Hypospadias repair was performed and he changed to a male gender. DNA sequence analysis disclosed a homozygous mutation in exon 4 of the 5α-reductase type 2 gene, alanine 228 for threonine. The heterozygous parents are first cousins of Pakistani origin. Am. J. Med. Genet. 80:269–272, 1998. © 1998 Wiley-Liss, Inc.     

SH3GL2 and CDKN2A/2B loci are independently altered in early dysplastic lesions of head and neck: correlation with HPV infection and tobacco habit

To understand the association of candidate tumour suppressor genes SH3GL2, p16^INK4a, p14^ARF, and p15^INK4b in the pathogenesis of head and neck squamous cell carcinoma (HNSCC), we studied the deletion, mutation, and methylation of these genes in 61 dysplastic lesions and 94 HNSCC samples. In mild dysplasia, SH3GL2, p16^INK4a, and p14^ARF showed a higher frequency of overall alterations (60–70%) than in p15^INK4b (40%). However, in subsequent stages of tumour progression, the alteration frequency of these genes did not change significantly. One novel mutation in common exon 2 of p16^INK4a/p14^ARF and three in exon 9 of SH3GL2 were seen. Concordance was seen in the expression of these genes with their molecular alterations. Deletions of INK4A‐ARF and p15^INK4b have a significant poor patient outcome. The alterations of p16^INK4a, p14^ARF, and p15^INK4b were positively correlated with tobacco and inversely with HPV, while SH3GL2 alterations were independent of these factors. Based on aetiological factors, four tumour subtypes were recognized: HPV^?tobacco^? (I), HPV⁺tobacco^? (II), HPV^?tobacco⁺ (III), and HPV⁺tobacco⁺ (IV). Groups III and IV showed a high frequency of p16^INK4a/p14^ARF/p15^INK4b alterations with significant poor patient outcome in comparison to group II. Our findings suggest that deregulation of SH3GL2‐associated signalling and p16^INK4a/p14^ARF/p15^INK4b‐mediated G1–S/G2–M checkpoints of cell cycle are independent pathways for the development of early dysplastic lesions of the head and neck. Copyright © 2008 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.     

Association of novel variants in the hepatocyte nuclear factor 4A gene with maturity onset diabetes of the young and early onset type 2 diabetes

Variants in hepatocyte nuclear factor 4A (HNF4A) cause maturity onset diabetes of the young (MODY 1). The objective of the study was to screen the coding and the promoter regions of HNF4A mutations in 87 unrelated South Indian subjects with clinically diagnosed MODY with severe forms of diabetes referred to a tertiary diabetes centre. In addition, we looked at the association of common polymorphisms in HNF4 A gene in subjects with MODY (n = 199), early onset type 2 diabetes (T2DM) (n = 505), late onset T2DM (n = 287) and normal glucose tolerance (NGT) (n = 247). We identified three novel mutations in the P2 promoter region of HNF4A, namely -1009 G/C, -129 T/C and -79 C/T. Co-segregation with diabetes was noted with the -1009 G/C and -129 T/C in one MODY family. We also studied eight single nucleotide polymorphisms (SNPs) of HNF4A gene. The frequency of the minor allele of the rs2144908 was significantly higher in subjects with MODY (p < 0.01) and that of rs736823 was significantly higher in early onset T2DM (p = 0.001). Minor allele frequency of rs1884614 and rs2071197 was significantly lower in early onset T2DM when compared to NGT subjects (p < 0.01). Minor allele frequency of Val255Met was significantly lower in MODY, early onset T2DM and late onset T2DM compared to NGT subjects (p < 0.01). This is the first report of MODY 1 mutations from India and shows that 3.4% of clinically diagnosed MODY subjects have MODY 1. In addition, we report SNPs of HNF4A that are both susceptible to, and protective against, MODY and early onset T2DM.     

Intracellular transport of acid β-glucosidase and lysosome-associated membrane proteins is affected in Gaucher's disease (G202R mutation)

Gaucher's disease (GD) is caused by an inherited deficiency of acid β-glucosidase with storage of glucosylceramides in the lysosomes of macrophages. This study identifies a G202R mutation in the acid β-glucosidase gene in an infant with severe neuronopathic (type 2) GD and only slightly reduced acid β-glucosidase activity. Western blot analysis, pulse chase experiments, and the thin frozen section immunogold method were used to analyse the implications of this mutation on the pathogenesis, clinical heterogeneity and diagnostic evaluation of GD. The results show that acid β-glucosidase persists in the patient's fibroblasts as a mannose-rich polypeptide in the endoplasmic reticulum and is not transported to the lysosomes. By contrast, high expression of the lysosome-associated membrane proteins LAMP-1 and LAMP-2, saposin C, and cathepsin D was observed in the patient's lysosomes. Immunogold labelling of the integral membrane proteins LAMP-1 and LAMP-2 increases significantly at the cell surface of Kupffer cells and fibroblasts as well as at the apical membrane of hepatocytes. In addition, LAMP-1 and LAMP-2 associate with the bilayer of stored glucosylceramide. It is concluded that defective intracellular transport of mutant acid β-glucosidase from the endoplasmic reticulum to lysosomes leads to a more severe clinical phenotype than the residual enzyme activity may indicate. Furthermore, the detection of LAMP in the tubular bundles of undigested glucosylceramides, as well as their increased concentration at the surfaces of the affected cells, suggests that these proteins play a role in the storage or removal of substrate in GD. Intracellular targeting of acid β-glucosidase and LAMP contributes to the broad phenotypic heterogeneity of GD. Copyright © 1999 John Wiley & Sons, Ltd.     

The IHPK1 gene is disrupted at the 3p21.31 breakpoint of t(3;9) in a family with type 2 diabetes mellitus

Type 2 diabetes mellitus (T2DM) is a group of multifactorial disorders due to either defective insulin secretion or action. Despite the fact that numerous genetic researches of T2DM have been pursued, the pathogenic mechanisms remain obscure. We encountered a T2DM family associated with a balanced reciprocal translocation, t(3;9)(p21.31;q33.1). To isolate a candidate gene susceptible to T2DM, we constructed physical maps covering both the 3p and 9q breakpoints of the translocation in the family. Consequently, the inositol hexaphosphate kinase 1 gene (IHPK1) (OMIM *606991) was found to be disrupted at the 3p21.31 breakpoint. We then carried out sequence analysis for all coding regions of IHPK1 in 405 unrelated T2DM patients in order to validate whether aberrations of the gene are common in T2DM patients, but we failed to detect any pathogenic changes. The disruption of IHPK1 or another predisposing gene affected by position effect of the translocation may explain the T2DM phenotype at least in this family. Alternatively, the IHPK1 disruption in the family is a chance association.     

Acute phase proteins but not activated microglial cells are present in parenchymal β/A4 deposits in the brains of patients with hereditary cerebral hemorrhage with amyloidosis-Dutch type

With immunohistochemical staining methods on cryostat sections we investigated the brains of three patients with hereditary cerebral hemorrhage with amyloidosis-Dutch type, one of the cerebral β/A4 amyloid diseases. Immunostaining for β/A4 protein revealed numerous non-fibrillar β/A4 depositions (amorphous or diffuse plaques) in the brain parenchyma in addition to extensive vascular amyloid deposition. All amorphous plaques contain complement proteins and ₁-antichymotrypsin but activated microglial cells expressing major histocompatibility (MHC) class II antigens HLA-DR and leucocyte adhesion molecules belonging to the lymphocyte-function-associated antigen (LFA)-1 family are virtually absent in cortical gray matter. Our findings are discussed from the view that a cascade of events including acute phase proteins and activated microglial cells are involved in classical amyloid plaque formation.     

Oculocutaneous albinism type 2 (OCA2) with homozygous 2.7-kb deletion of the P gene and sickle cell disease in a Cameroonian family. Identification of a common TAG haplotype in the mutated P gene

In this study, we report on a Cameroonian family from the Ewondo ethnic group, presenting with three oculocutaneous albinism type 2 (OCA2) patients homozygous for the 2.7-kb deletion of the P gene. In one of these patients OCA2 was associated with sickle cell anaemia and in two with the sickle cell trait. We took this opportunity to determine single nucleotide polymorphism (SNP) haplotypes within the P gene in this family in comparison with a group of 53 OCA2 patients homozygous for the same mutation and with a matched unrelated full-coloured control group of 49 subjects, originating from seven different ethnic groups of Southern Cameroon including Ewondo. A combination of five exonic and intronic SNPs in the OCA2 gene was genotyped by sequencing PCR products. We found 3 different haplotypes (TAGCT, TAGTT and TAGCC with frequencies of 0.66, 0.28 and 0.06, respectively) associated with the mutation in the 53 OCA2 patients, while 11 different haplotypes were observed in the control group. These observations suggest that the mutation appeared on the relatively frequent haplotype TAGCT, and that the two other haplotypes are derived from two independent recombination events. These haplotypic data, associated with a value of 1/15,000 for the prevalence of the 2.7-kb mutation, a present effective population size of 10,000,000 for Cameroon and a recombination rate of 0.0031, allowed us to estimate that this mutation originated 4,100–5,645 years ago.