Pedigree and haplotype. Our index patient (1) and his sister (2) share only one halplotype in the Alström region. Additionally, the haplotype they share is not the same as their cousins (3-5). Our patient's cousin (4) and patient's sister (2) share a single nucleotide polymorphism (non-disease causing) in Bardet-Biedl syndrome 5 (BBS5), which was probably passed down from their grandfather. It is not really relevant, because it is not causative. Our patient's cousin is homozygous in the ALMS1 region and his brother is a 'carrier', which suggests a diagnosis of Alström syndrome could be correct.