## Abstract

We derive the conditional probabilities for estimating the sex ratio in families ascertained through affected males for the study of X-linked recessive diseases. These conditional probabilities correct for the fact that the probability that a family will be ascertained increases with the number of males in the family. Data from four published studies for X-linked ichthyosis vulgaris are analyzed, three having an excess of males and one having a highly statistically significant excess of males. It is not known if this difference in the two samples represents a biological difference between the two populations or an unrecognized ascertainment bias.

Original language | English |
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Pages (from-to) | 741-746 |

Number of pages | 6 |

Journal | American journal of human genetics |

Volume | 31 |

Issue number | 6 |

State | Published - Dec 1 1979 |